Olive Leaf Complex Natural Olive Leaf Flavor [Discontinued] by Barlean's

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Athletic performance. Although there has been interest in using oral caffeic acid for athletic performance, there is insufficient reliable information about the clinical effects of caffeic acid for this purpose.
• Obesity. Although there has been interest in using oral caffeic acid for weight loss, there is insufficient reliable information about the clinical effects of caffeic acid for this purpose. More evidence is needed to rate caffeic acid for these uses.

(Read more about CAFFEIC ACID)

POSSIBLY EFFECTIVE

• Chronic venous insufficiency (CVI). Oral diosmin, as part of a micronized purified flavonoid fraction, seems to be beneficial for reducing symptoms of CVI. It is unclear if oral diosmin alone is beneficial. Details: Most clinical research shows that taking 2-3 tablets daily of a specific combination product (Daflon 500, Les Laboratoires Servier) containing micronized purified flavonoid fraction (MPFF), providing diosmin 450 mg and other flavonoids, such as hesperidin, 50 mg per tablet, for 2-6 months modestly improves symptoms of chronic venous diseases such as varicose veins and CVI, including leg pain, heaviness, swelling, and cramps, when compared with baseline or placebo (50892,54755,54799,98597,98609). Additionally, a large clinical study in patients with CVI shows that results are similar when a chewable form of this product taken 1000 mg daily (Daflon 1000, Les Laboratoires Servier) is compared with 500 mg tablets taken twice daily (112796). An observational study in adults with advanced CVI suggests that taking MPFF 1000 mg, consisting of 90% micronized diosmin and 10% other flavonoids, daily for 6 months in addition to conservative treatment, mainly compression therapy, is associated with improved symptoms (e.g., varicose veins, venous edema, pain) and reduced subcutaneous adipose tissue thickness when compared to baseline (112795). The validity of these findings is limited by a lack of a comparator group. In patients with mild to moderate pelvic venous disorder due to valvular incompetence, two preliminary clinical trials show that this same combination product is beneficial for reducing pain and other symptoms (105287,108150). In one study, taking 1000 mg daily for 2 months modestly improves quality of life and reduces most symptoms, including pain, tenderness, edema, heaviness, and discomfort, when compared with placebo (108150). Other preliminary clinical research shows that dosing based on severity as either 1000 mg daily for 2 months or 1000 mg twice daily for one month and then 1000 mg once daily for an additional month, reduces pelvic pain by a moderate and large amount, respectively, when compared to baseline. The average time to pain relief was 13.7 or 3.1 days, respectively, for each dosing group. Pelvic venous congestion was reduced more in the higher dose group as calculated following transvaginal and transabdominal duplex ultrasound scanning (DUS) and single-photon emission computed tomography (SPECT) of the pelvic veins (105287). Micronized diosmin in combination with other flavonoids has also been compared with non-micronized diosmin alone. Although taking non-micronized diosmin 900 mg daily modestly improved clinical symptoms when compared with baseline in early research, taking 1000 mg of micronized purified flavonoid fraction daily for 2 months was more effective (54935,54950). However, more recent preliminary clinical research in a well-defined patient population with pre-CVI symptoms shows that taking one tablet of a specific non-micronized diosmin (Flebodia, Laboratoire Innotech International) 600 mg daily for 6 months is as effective for reducing leg pain, fatigue, swelling, or tension as taking 1000 mg daily of micronized purified flavonoid fraction providing diosmin plus other flavonoids (Daflon, Laboratórios Servier do Brasil Ltda.) (105293). Also, in a mixed population with pre-CVI and CVI, clinical research shows that taking a specific diosmin (as µsmin Plus, Giellepi S.p.A.) 450 mg once daily for 8 weeks reduces edema by approximately 4% when compared with placebo. Additionally, 98% of patients taking this diosmin product experienced symptom relief, compared with only 29% of those taking placebo (105294). The discrepancy in these findings may be related to the different products used or the severity of disease in the included patient populations.
• Hemorrhoids. Oral diosmin, as part of a micronized purified flavonoid fraction or in combination with other compounds, seems to be beneficial for hemorrhoids. Details: A meta-analysis of the available research, as well as individual clinical trials, show that taking three tablets of a specific combination product (Daflon 500, Les Laboratoires Servier), containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet, twice daily for 4-5 days followed by two tablets of this same product twice daily for up to 3 months, improves signs and symptoms of internal hemorrhoids. The combination appears to stop acute bleeding in up to 92% of patients after 4 days of treatment. It may also reduce symptoms such as anal discomfort, pain, discharge, and local lesions within 2 days of treatment. The combination also seems to reduce the duration and intensity of hemorrhoidal flare-ups (4861,4900,8077,54970,105282) and improve recovery after hemorrhoidopexy or hemorrhoidectomy (54793,105284). Maintenance treatment with one tablet of this product twice daily for 2-3 months following acute treatment for hemorrhoids decreases the relapse rate and improves symptoms, including pain, itching, tenesmus, mucous discharge, redness, swelling, and bleeding (4861,54954). Diosmin has also been evaluated in combination with hesperidin and troxerutin. Clinical research in adults with acute hemorrhoidal crisis shows that taking a combination product (Triade H, Omikron Italia Srl) providing these ingredients in tapered doses over 43 days reduces progressive pain in approximately 88% of patients, bleeding in 64% of patients, and anal itching in 56% of patients. These changes are significant when compared with placebo (93885). This product was given as one sachet of powdered diosmin 300 mg, troxerutin 300 mg, hesperidin 300 mg, and vitamin C 12 mg mixed in water orally three times daily for 3 days, then two sachets daily for 2 days, then one sachet daily for seven days, followed by one tablet containing diosmin 300 mg, troxerutin 300 mg, and hesperidin 100 mg daily for one month. Diosmin has also been evaluated in combination with bulk laxatives. Diosmin 600 mg three times daily for 4 days, then 300 mg twice daily for 10 more days in conjunction with psyllium 11 grams daily, seems to modestly improve symptoms after 4 days of treatment (4898). However, this combination does not seem to be as effective as the use of micronized purified flavonoid fraction.
• Venous leg ulcers. Oral diosmin, as part of a micronized purified flavonoid fraction, seems to be beneficial for venous leg ulcers. Details: Clinical research in adults with venous leg ulcers up to 10 cm in size shows that taking two tablets daily of a specific combination product (Daflon 500, Les Laboratoires Servier), containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet for 2 months in conjunction with compression dressing more than doubles the number of patients with complete healing of ulcers when compared with placebo. Also, the time to healing was reduced. However, in one study there was no effect on the ulcer surface area, symptoms, or healing of ulcers greater than 10 cm in size (10229,54972,54984).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Back pain. It is unclear if oral diosmin is beneficial for back pain. Details: Preliminary clinical research in patients with radicular low back pain shows that taking diosmin (Nanjing Chia Tai Tianqing Pharmaceutical Co., Ltd) moderately improves subjective pain scores after 8 weeks and reduces the use of rescue analgesics after 24 months similarly to intravenous dexamethasone every 3 days with monthly administration of mannitol. Diosmin was administered at doses of 900 mg orally three times daily for 2 weeks, then 900 mg twice daily for 2 weeks, then 450 mg twice daily for one month (95043).
• Chronic prostatitis and chronic pelvic pain syndrome (CP/CPPS). It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction, is beneficial for CPPS. Details: Preliminary clinical research shows that taking one tablet daily of a specific combination product containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet (Daflon) for 8 weeks in combination with standard treatment involving antibiotics and anti-inflammatory drugs improves overall symptoms of CPPS at 6 months similarly to taking alfuzosin, an alpha-blocker, along with standard treatment for 12 weeks. However, there was no benefit when the diosmin product was used alone, without standard treatment. At 12 months, symptoms were modestly more improved in those taking alfuzosin (105297).
• Coronary artery bypass graft (CABG) surgery. It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction, is beneficial for patients undergoing CABG surgery. Details: In patients about to undergo CABG for impaired left ventricular function, clinical research shows that a specific combination product containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet (Daflon 500, Les Laboratoires Servier), taken as 3000 mg daily for 4 days, followed by 1000 mg daily for 3 days preoperatively, does not reduce the postoperative length of stay in the intensive care unit or hospital, inotropic medication requirements, or left ventricular ejection fraction when compared with placebo. However, levels of troponin I and lactate were lower, and patient status based on the New York Heart Association (NYHA) classification was modestly improved (105285).
• Diabetes. It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction or in combination with other compounds, is beneficial for diabetes. Details: Preliminary clinical research in females with type 2 diabetes shows that taking one tablet of a specific combination product containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet (Daflon 500, Les Laboratoires Servier) twice daily for 45 days modestly decreases glycated hemoglobin (HbA1c) and serum glucose when compared to baseline (54977). However, a prospective observational study in patients with type 1 or type 2 diabetes has found that taking a specific product (Flebotrofine, AMNOL Chimica Biologica) containing diosmin for 3 months is not associated with improvements in HbA1c, cholesterol, or triglyceride levels when compared with baseline. Other ingredients in this product included L-arginine, troxerutin, hesperidin, black currant extract, and gotu kola extract (108151). The validity of these findings is limited by the lack of a comparator group.
• Diabetic neuropathy. It is unclear if oral diosmin is beneficial for diabetic neuropathy. Details: A small clinical study in adults with type 2 diabetes, peripheral neuropathy, and metabolic syndrome on oral antidiabetic therapy shows that taking diosmin 1 gram daily (Dioven, Amryia Pharmaceutical Co.) for 12 weeks, with or without hesperidin 1 gram daily, improves diabetic neuropathy as measured by the Michigan Neuropathy Screening Instrument (MNSI) when compared with standard care alone. In addition, the improvements in measures of diabetic neuropathy were greater when diosmin and hesperidin are taken together compared with either supplement alone, suggesting a synergistic effect (112797). However, the validity of this study is limited by inadequate blinding.
• Lymphedema. It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction or in combination with other compounds, is beneficial for lymphedema. Details: Clinical research shows that taking two tablets of a specific combination product (Daflon 500, Les Laboratoires Servier) containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet daily for 6 months may improve drainage of lymph from the arms after breast cancer surgery, but does not reduce arm swelling or other clinical signs of lymphedema, when compared with placebo (10227). A small clinical study in patients with severe breast cancer-related lymphedema shows that taking a specific combination product (Linfaden, OMEGA PHARMA Srl) containing diosmin 200 mg, coumarin 30.6 mg, and arbutin 3.7 mg twice daily for 2 weeks and then once daily for 4 weeks, in addition to complex congestive therapy (CDT), reduces upper limb excess volume by 521 mL, compared with a 256 mL reduction in the CDT-only group (101646). It is unclear if the effects are due to diosmin, other ingredients, or the combination.
• Metabolic syndrome. It is unclear if oral diosmin is beneficial for metabolic syndrome. Details: A small clinical study in adults with metabolic syndrome, type 2 diabetes, and peripheral neuropathy on oral antidiabetic therapy shows that taking diosmin 1 gram daily (Dioven, Amryia Pharmaceutical Co.) for 12 weeks, with or without hesperidin 1 gram daily, reduces body mass index, fasting blood glucose, triglycerides, and low-density lipoprotein cholesterol but does not change systolic blood pressure, diastolic blood pressure, or high-density lipoprotein cholesterol when compared with standard care alone. These effects are enhanced when diosmin is taken in combination with hesperidin compared with either supplement taken alone or control (112797). However, the validity of this study is limited by inadequate blinding.
• Minor bleeding. It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction, is beneficial for minor bleeding. Details: Preliminary clinical research in patients with idiopathic epistaxis shows that taking a specific combination product containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg (Daflon, Servier) daily for 1-3 months modestly reduces emergency room visits and need for cauterization due to failure of light nasal packing when compared with no treatment (101644). The validity of this study is limited by the lack of blinding.
• Ovarian hyperstimulation syndrome. It is unclear if oral diosmin is beneficial for reducing the occurrence of ovarian hyperstimulation syndrome. Details: Observational research in patients at high risk of ovarian hyperstimulation syndrome (OHSS) following a previous cancellation of embryo transfer has found that taking diosmin 1000 mg twice daily for 10 days after oocyte retrieval is associated with a 6.2% incidence of moderate to severe OHSS, compared to 13.4% in the patients that had not received diosmin. Also, there were no cases of severe OHSS (105295). This study is limited by its retrospective, observational design.
• Varicose veins. It is unclear if oral diosmin, as part of a micronized purified flavonoid fraction, is beneficial for varicose veins. Details: In patients with mild varicose veins such as spider veins or reticular veins, some observational research has evaluated the use of a specific combination product (Detralex; Servier France) containing diosmin 450 mg plus other flavonoids, such as hesperidin, 50 mg per tablet, taken as one tablet twice daily for 6 weeks, starting 2 weeks before sclerotherapy. This research has found that taking this product is associated with decreased leg heaviness, pain, swelling sensation, night cramps, and itching after sclerotherapy when compared with patients not using this treatment. It is also associated with a reduction in pain and swelling sensation from before sclerotherapy when compared with those not using this treatment. Additionally, the use of this product is associated with a slight reduction in hyperpigmentation following sclerotherapy, although there were no benefits on other sclerotherapy-related adverse effects, including phlebitis and necrosis (105283). In patients with varicose veins of greater severity, observational research has found that taking this same product 1000 mg daily for 30 days, starting on the day of mechanochemical ablation with mini-phlebectomy or foam sclerotherapy, is associated with a modest reduction in the severity of varicose veins, such as swelling, heaviness, and itching, after 30 days, but not after 7 or 14 days, when compared with no treatment (105286). For more information on the use of diosmin for chronic venous insufficiency (CVI), which can occur concomitantly with varicose veins, refer to the CVI discussion.
• Venous thromboembolism (VTE). It is unclear if oral diosmin is beneficial for prevention of VTE. Details: In patients experiencing their first femoropopliteal deep vein thrombosis (DVT), preliminary clinical research shows that taking diosmin 600 mg daily for 12 months, in addition to rivaroxaban and elastic compression stockings, reduces the frequency of post-thrombotic syndrome to 9%, compared to 49% in those not taking diosmin. There were also fewer patients with chronic venous disease or DVT recurrence at 12 months (105296). More evidence is needed to rate diosmin for these uses.

(Read more about DIOSMIN)

POSSIBLY INEFFECTIVE

• Athletic performance. Oral quercetin does not seem to improve athletic performance. Details: A pooled analysis of data from seven clinical trials shows that intake of quercetin does not improve maximal oxygen consumption or capacity to perform prolonged exercise in trained or untrained athletes when compared with placebo (91577). Additionally, one small clinical study in male soldiers shows that taking quercetin 500 mg twice daily for 8.5 days before a loaded treadmill marching test and a cycling time trial test does not affect ratings of perceived exertion, cycling time, or peak oxygen consumption during treadmill testing when compared with placebo (91578).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral quercetin is beneficial in older adults with age-related cognitive decline. Details: Preliminary research in healthy adults aged 60 to 80 years with age-related forgetfulness shows that drinking 500 mL of a barley-based beverage containing 110 mg quercetin glycoside calculated as isoquercitrin, daily for 40 weeks seems to improve reaction times when compared with placebo. However, increase in score on the mini-mental state examination (MMSE), reduction in accumulation of amyloid beta in the brain, and prevention of reduction in cerebral blood flow occur to a similar extent with quercetin and placebo (110008).
• Allergic rhinitis (hay fever). It is unclear if oral quercetin is beneficial in patients with allergic rhinitis. Details: A small clinical study in Japanese adults with allergic rhinitis shows that taking a specific quercetin product (Quercetin Phytosome, Indena SpA) 100 mg twice daily for 4 weeks does not improve scores related to quality of life, activities of daily living, nasal symptoms, or ocular symptoms on the Japanese Rhino-conjunctivitis Quality of Life Questionnaire (JRQLQ). However, scores related to fatigue and sleep quality improved when compared with placebo. Additionally, sneezing, rhinorrhea, and activities of daily living scores improved when another scale was used to assess the severity of allergic rhinitis (109620). Quercetin has also been evaluated in combination with other ingredients. A small clinical study in children aged 6-12 years with allergic rhinitis who had gone through a treatment phase with antihistamines and a specific combination of quercetin, perilla, and vitamin D3 (Lertal) 1 tablet daily for 4 weeks shows that taking this specific combination for an additional 4-12 weeks reduces the chance of having symptom exacerbations by approximately 50% when compared with no further treatment past the first 4 weeks. The number of days requiring rescue medication was also reduced from 28.5 days to an average of 9.6 days (104676).
• Alzheimer disease. Although there has been interest in using oral quercetin for Alzheimer disease, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Asthma. It is unclear if oral quercetin is beneficial in patients with asthma. Details: Preliminary clinical research in patients with mild-to-moderate asthma shows that taking a specific quercetin product (QFit, Indena SpA) 250 mg or 500 mg daily for 30 days along with conventional therapy reduces daytime and nighttime asthma symptoms, improves spirometry measures, and decreases the use of rescue inhalers when compared to baseline. Significant improvements in these outcomes were lacking in patients receiving conventional therapy alone (102540).
• Atherosclerosis. Although there has been interest in using oral quercetin for atherosclerosis, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Autism spectrum disorder. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in children aged 4-10 years with autism shows that taking a combination of luteolin 10 mg/kg, quercetin 7 mg/kg, and rutin 3 mg/kg in olive oil for 26 weeks improves hyperactivity, irritability, and lethargy by a moderate to large amount, and improves some indices of functioning, such as daily living and social behavior, by a small amount when compared with baseline. The validity of these findings is limited by the lack of a comparator group (96765).
• Benign prostatic hyperplasia (BPH). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking one tablet of a specific combination product (Difaprost) containing quercetin, beta-sitosterol, and saw palmetto daily for 3 months does not improve general symptoms of BPH when compared to baseline (96784). The validity of these findings is limited by the lack of a comparator group.
• Beta-thalassemia. It is unclear if oral quercetin is beneficial in patients with beta-thalassemia. Details: Preliminary clinical research in transfusion-dependent patients with beta-thalassemia shows that taking quercetin 500 mg daily for 12 weeks reduces iron and ferritin levels, increases transferrin levels, and decreases transferrin saturation when compared with placebo. However, total iron binding capacity was not improved. These results suggest that quercetin might reduce iron overload, which is a complication of frequent blood transfusions in these patients (102541).
• Cancer. Although there has been interest in using intravenous or intraperitoneal quercetin for cancer, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Canker sores. Topical quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a cream containing quercetin, glycol, zinc, and Myristica (Rootage skin cream, Elsi-Si) three times daily results in complete healing of minor canker sores and reduces pain in 100% of patients within 7-10 days, compared with only 60% of patients using a benzydamine hydrochloride mouthwash three times daily (104677).
• Cardiovascular disease (CVD). It is unclear if oral quercetin is beneficial for CVD prevention. Details: Population research has found that increasing dietary intake of quercetin from food sources such as tea, onions, and apples is associated with a significantly reduced risk of heart disease-related mortality in elderly males (7726). However, preliminary clinical research shows that quercetin 1 gram daily for 28 days does not significantly improve platelet aggregation, thromboxane B2 production, blood pressure, heart rate, or serum lipid levels when compared with placebo in healthy people (1998).
• Cataracts. Although there has been interest in using oral quercetin for cataracts, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Chemotherapy-induced cystitis. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with bladder cancer undergoing intravesical chemotherapy shows that taking a specific combination product (Ialuril, IBSA Farmaceutici) containing quercetin 400 mg, hyaluronic acid 40 mg, chondroitin sulfate 400 mg, and curcumin 400 mg every morning, starting 7 days before the first instillation and ending 30 days after the last instillation, improves lower urinary tract symptoms as measured using a visual analog scale and the International Prostate Symptom Score (IPSS) at 13 months when compared with placebo (109622).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral quercetin for CFS, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Chronic venous insufficiency (CVI). Although there has been interest in using oral quercetin for CVI, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Colorectal cancer. Although there has been interest in using oral quercetin for colorectal cancer prevention, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Contrast induced nephropathy. It is unclear if oral quercetin is beneficial for the prevention of contrast induced nephropathy. Details: Preliminary clinical research in patients undergoing coronary catheterization shows that taking quercetin 500 mg every 8 hours, starting two days prior to contrast imaging and continuing for two days after, does not appear to prevent contrast induced nephropathy when compared with a control group not receiving quercetin (102539). Given its small size, this study may have been inadequately powered to detect significant differences for this outcome.
• Coronavirus disease 2019 (COVID-19). Analysis of several small, open-label clinical studies suggest that oral quercetin may modestly reduce hospitalizations and intensive care unit (ICU) admissions in patients with COVID-19. Whether quercetin is beneficial in patients with severe COVID-19 is unclear. Details: A meta-analysis of 6 open-label clinical studies in patients with COVID-19 shows that taking quercetin 260-1000 mg daily for 7-30 days along with standard therapy with analgesics, antipyretics, antibiotics, remdesivir, or favipiravir reduces the odds of intensive care unit (ICU) admission by 69% and the odds of hospitalization by 75% but does not decrease the rate of all-cause mortality or the rate of recovery upon follow-up when compared with standard care (111412). However, the interpretation of these findings is limited by differences in the severity of COVID-19, doses and durations of quercetin therapy, and standard of care regimens used across the included studies. In outpatients in the early stages of COVID-19, two small, open-label clinical studies included in the meta-analysis above show that taking quercetin 200 mg two or three times daily for 14-30 days along with standard care reduces time to symptom resolution when compared with standard care alone. However, these studies show mixed results with respect to prevention of hospitalization, ICU admission, and death (106498,106499). More recent research in patients with early-stage, mild to moderate COVID-19 symptoms shows that taking quercetin 500 mg three times daily for 1 week, followed by 500 mg twice daily for 1 week, increases the rate of symptom resolution and achieving a negative COVID-19 test at 1 week by 116% and 183%, respectively, when compared with placebo (110009). Quercetin has also been evaluated in patients with severe COVID-19. A small, open-label clinical study of patients with severe COVID-19 who have not been admitted to the ICU shows that taking quercetin 500 mg twice daily for 7 days along with remdesivir or favipiravir shortens the time to discharge by around 1.5 days and improves symptoms of weakness and lethargy, but does not improve other symptoms of COVID-19 or reduce the risk of ICU admission or death, when compared with remdesivir or favipiravir alone (107450).
• Depression. It is unclear if oral quercetin is beneficial for depression in patients with a recent myocardial infarction (MI). Details: A moderate-sized clinical study in adults 6-8 weeks post-MI conducted in Iran shows that taking quercetin 500 mg daily for 8 weeks does not improve self-reported depression scores when compared with placebo (112228). However, the severity of patients' depression was minimal at baseline, which limits the power to detect a difference between groups.
• Diabetes. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with type 2 diabetes who are not using hypoglycemic agents shows that taking a specific combination of quercetin, myricetin, and chlorogenic acid (Emulin, Anderson Global Group LLC) 250 mg daily for 7 days reduces levels of fasting and postprandial glucose by about 5% when compared to baseline. These changes were significantly different than the slight increases seen in the placebo group. In patients taking metformin along with the combination supplement, fasting blood glucose levels decreased by about 20%, compared with a decrease of less than 1% with metformin alone (96779).
• Exercise-induced muscle damage. It is unclear if oral quercetin is beneficial for preventing muscle damage associated with exercise. Details: Some clinical research shows that taking quercetin 500 mg twice daily for 3 weeks prior to and during an endurance run or cycling event does not attenuate exercise-induced muscle damage, soreness, or inflammation (16429,16431). However, a series of two small clinical trials show that taking quercetin 1000 mg daily for 14 days prior to eccentric exercise modestly attenuates the decline in the maximal intensity of a contraction when compared with placebo (99236,104226). Additionally, this dosing regimen appears to modestly accelerate the recovery of muscle strength and neuromuscular function after exercise when compared with placebo (104226).
• Exercise-induced respiratory infections. It is unclear if oral quercetin is beneficial for prevention of respiratory infections induced by exercise. Details: Preliminary clinical research shows that taking quercetin 500 mg twice daily for 3 weeks before, and continuing during 3 days of prolonged, intense cycling, reduces the incidence of upper respiratory infections in the 14 days following the heavy exercise (16430).
• Gout. Although there has been interest in using oral quercetin for gout, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Herpes labialis (cold sores). Although there has been interest in using oral quercetin for herpes labialis, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Hypercholesterolemia. It is unclear if oral quercetin is beneficial for improving cholesterol levels. Details: Multiple meta-analyses show that taking quercetin does not affect total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, or triglycerides (TG) when compared with placebo (96783,104229). However, a subgroup analysis shows that taking quercetin for at least 8 weeks seems to reduce TG levels by 13 mg/dL and increase HDL levels by 3 mg/dL, compared with no change in patients who took quercetin for less than 8 weeks (104229). It is unclear these patients had elevated cholesterol levels at baseline.
• Hypertension. It is unclear if oral quercetin is beneficial for reducing blood pressure. Details: Three meta-analyses show that taking quercetin 100-1000 mg daily for 4-12 weeks decreases systolic and diastolic blood pressure by 2-4 mmHg and 2-3 mmHg, respectively, when compared with placebo. However, only two of the studies included in these analyses evaluated patients with hypertension (16424,96775,104229,109617). Additional clinical research in patients with mild hypertension shows that taking a single dose of quercetin 1095 mg can lower systolic and diastolic blood pressure by 7 mmHg and 3 mmHg, respectively, when measured 10 hours later (96780). Overall, the benefit of quercetin on blood pressure seems modest; it is unclear whether the improvement is clinically significant for patients with hypertension.
• Kidney transplant. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that a specific product containing a combination of quercetin 20 mg and curcumin 480 mg (Oxy-Q, Farr Labs) taken once or twice daily in combination with anti-rejection medications, starting within 24 hours of a kidney transplant and continuing for one month, improves early function of the graft and reduces serum creatinine when compared with taking placebo in combination with anti-rejection medications (16420).
• Lung cancer. It is unclear if oral quercetin is beneficial in lung cancer prevention. Details: Epidemiologic research has found that increasing dietary intake of quercetin is associated with a reduced risk of lung cancer in smokers (96778).
• Metabolic syndrome. It is unclear if oral quercetin is beneficial in patients with metabolic syndrome. Details: A meta-analysis of small clinical studies shows that taking quercetin 100-1000 mg daily for 4-12 weeks does not improve fasting blood glucose, glycated hemoglobin, or insulin levels when compared with placebo in patients with risk factors for metabolic syndrome, such as type 2 diabetes, prehypertension, polycystic ovary syndrome, and/or obesity (100967). Additional research is needed to determine if quercetin is beneficial in patients with existing metabolic syndrome.
• Niacin-induced flushing. Although there has been interest in using oral quercetin for niacin-induced flushing, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Obesity. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking quercetin 500 or 1000 mg daily for 12 weeks, in addition to niacin 5 mg or 10 mg and vitamin C 125 mg or 250 mg, does not reduce body weight or fat mass when compared with placebo in adults considered overweight or obese based on body mass index (BMI) (104678).
• Oral mucositis. It is unclear if oral quercetin is beneficial in patients with oral mucositis. Details: One small clinical study shows that taking quercetin 250 mg twice daily for 4 weeks does not prevent oral mucositis associated with chemotherapy when compared with placebo (96776).
• Ovarian cancer. It is unclear if oral quercetin is beneficial for ovarian cancer prevention. Details: One epidemiologic study found no association between dietary intake of quercetin and related flavonols and the risk of ovarian cancer (16428).
• Pancreatic cancer. It is unclear if oral quercetin is beneficial for pancreatic cancer prevention. Details: Epidemiologic studies have found that a high dietary intake of quercetin and related flavonols might reduce the risk of pancreatic cancer, especially in male smokers (16426,16427).
• Peptic ulcers. Although there has been interest in using oral quercetin for peptic ulcers, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Physical performance. It is unclear if oral quercetin is effective for improving physical performance in older adults. Details: A small clinical study in Japanese individuals 50-74 years of age shows that taking quercetin glycosides 200 mg or 500 mg daily along with low-intensity resistance training 3 days weekly for 24 weeks does not improve muscle size or lean body mass, but may reduce muscle stiffness, when compared with placebo (109621).
• Polycystic ovary syndrome (PCOS). It is unclear if oral quercetin is beneficial for improving hormone levels or pregnancy rates in patients with PCOS. Details: Clinical research in patients with PCOS shows that taking quercetin 1000 mg daily for 12 weeks reduces testosterone and luteinizing hormone (LH) levels by 9% and 3%, respectively, when compared to baseline; both of these improvements were significant when compared with placebo. Insulin resistance also improved by 18% when compared to baseline, which was significant when compared with placebo (96782). In a similar group of patients with higher levels of insulin resistance at baseline, taking the same dose of quercetin modestly reduced testosterone and LH levels when compared with placebo; however, there was no improvement in insulin resistance (99237). These disparate outcomes might be due to different baseline levels of insulin resistance. Also, it is unclear if these changes are associated with an improvement in the clinical symptoms of PCOS. Quercetin has also been evaluated for improving pregnancy rates in adults with PCOS and infertility. A small clinical study shows that taking quercetin 500 mg daily for 40 days increases pregnancy rates when compared with placebo. Quercetin supplementation also improves the grading of oocytes, but not the quality of embryos, in those undergoing in vitro fertilization (IVF). Nearly 84% of patients taking quercetin became pregnant spontaneously or via IVF in the 6 months following initiation of quercetin supplementation. Only 11% of patients taking placebo became pregnant during the study, all through IVF (109618). Due to a short duration of follow-up, it is unclear whether quercetin improves live birth rates.
• Prostatitis. It is unclear if oral quercetin is beneficial in patients with prostatitis. Details: Preliminary clinical research shows that taking quercetin 500 mg twice daily for one month reduces pain and improves quality of life, but does not seem to affect voiding dysfunction, in patients with chronic, nonbacterial prostatitis when compared with placebo (481).
• Rheumatoid arthritis (RA). It is unclear if oral quercetin is beneficial in patients with RA. Details: In patients with RA, clinical research shows that taking quercetin 500 mg daily for 8 weeks improves morning stiffness, morning pain, and after-activity pain when compared with placebo. However, taking quercetin does not seem to improve the number of swollen or tender joints or the disease activity score when compared with placebo (96774).
• Schizophrenia. Although there has been interest in using oral quercetin for schizophrenia, there is insufficient reliable information about the clinical effects of quercetin for this condition.
• Upper respiratory tract infection (URTI). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking quercetin 500 mg or 1000 mg daily for 12 weeks, in combination with vitamin C 500 mg or 1000 mg daily or niacin 20 mg or 40 mg daily, does not reduce the frequency or severity of URTIs. However, in a subgroup analysis of physically fit individuals 40 years and older, the severity of URTIs and the number of sick days related to URTIs were reduced by 36% and 31%, respectively, when quercetin 1000 mg was compared with placebo (104679).
• Urethral syndrome. Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking one tablet daily of a specific formulation containing quercetin, bromelain, chondroitin sulfate, gotu kola, rhodiola, and barbed skullcap (Cistiquer, Deakos) for 7 weeks reduces urinary urgency by 91% when compared with baseline. Also, 55% of patients reported no discomfort associated with urination. This combination product was reported to be at least as effective as intravesical administration of betamethasone 8 mg plus gentamicin 80 mg twice weekly (96777).
• Urinary tract infections (UTIs). Oral quercetin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking 1-2 capsules of a combination of hyaluronic acid, chondroitin sulfate, curcumin, and quercetin daily for 15 days each month, in combination with the use of local topical estrogen therapy (0.005% estriol vaginal gel) for up to 12 months, increases the number of women cured of recurrent UTIs to 66%, compared with only 34% of those taking the oral combination product or the vaginal estrogen product alone (96781). More evidence is needed to rate quercetin for these uses.

(Read more about QUERCETIN)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Aging skin. It is unclear if topical rutin is beneficial for aging skin. Details: Preliminary clinical research shows that topical application of a cream containing rutin 2% twice daily for 4 weeks reduces signs of skin aging around the eye in females aged 30-50 years. Skin dermal density is improved by 20%, area of crow's feet is reduced by 26%, and the number of wrinkles under the eye is reduced by 53% when compared with placebo (92236).
• Autism spectrum disorder. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in children 4-10 years-old with autism spectrum disorder shows that taking a product containing rutin 3 mg/kg, luteolin 10 mg/kg, and quercetin 7 mg/kg daily for 26 weeks improves aspects of behavior, such as hyperactivity, irritability, and lethargy, by a moderate to large amount when compared to baseline. It also seems to improve some indices of functioning, such as daily living and social behavior, by a small amount. These improvements were considered to be greater than expected when taking aging into consideration; however, no placebo was used in this study (96765).
• Diabetes. It is unclear if oral rutin is beneficial for diabetes. Details: A small clinical study in adults with type 2 diabetes conducted in Iran shows that taking rutin 500 mg twice daily for 3 months reduces fasting blood glucose and glycated hemoglobin by approximately 40 mg/dL and 1%, respectively, and modestly reduces triglycerides and total and low-density lipoprotein cholesterol when compared with placebo (112182). The interpretation of these findings is limited by the omission of data regarding concurrent diabetes medications. A small observational study in patients with a family history of type 1 diabetes shows that taking a specific product (Mucos Pharma) containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg daily for 24 months is not associated with reduced incidence of type 1 diabetes at 8 years (99472).
• Exercise-induced respiratory infections. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in non-elite male runners shows that taking a combination product (Wobenzym Plus, Mucos Pharma) providing rutin 600-1200 mg, trypsin 288-576 mg, and bromelain 540-1080 mg daily for 3 weeks, starting one week before a marathon, does not reduce the risk of a post-race respiratory tract infection when compared with placebo (96766).
• Hemorrhoids. Although there is interest in using oral rutin for hemorrhoids, there is insufficient reliable information about the clinical effects of rutin for this condition.
• Inflammatory bowel disease (IBD). Although there is interest in using oral rutin for IBD, there is insufficient reliable information about the clinical effects of rutin for these conditions.
• Lymphedema. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some clinical research in patients who have undergone a mastectomy shows that taking a specific combination product containing rutin, pancreatin, papain, bromelain, trypsin, and chymotrypsin (Wobenzym N, Mucos Pharma) daily for 7 weeks reduces arm swelling associated with lymphedema when compared with diuretics (24560). Also, preliminary clinical research in patients with primary or secondary lymphedema of the upper or lower limbs shows that taking a combination product containing rutin 300 mg, bromelain 100 mg, and sweet clover 100 mg daily for 6 months decreases pitting, limb volume, pain, and quality of life when compared to baseline (103298). The validity of these findings is limited by the lack of a comparator group. Also, it is unclear if these effects are due to rutin, other ingredients, or the combination.
• Multiple sclerosis (MS). Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A preliminary clinical study in patients with relapsing-remitting MS shows that taking an enzyme combination containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg per tablet for at least 3 months does not affect the progression of disability, relapse rate, or central nervous system lesions when compared with placebo (99468). The validity of these results are limited by the short duration of treatment.
• Obesity. It is unclear if oral rutin is beneficial for obesity. Details: In Japanese adults with a body mass index (BMI) of 23-30 kg/m2, a small clinical trial shows that taking a specific monoglucosyl rutin ( αG Rutin PS) 200 mg or 400 mg daily for 8 weeks reduces the area of visceral fat by 2.4 cm and 3.5 cm, respectively, compared with an increase of 5.2 cm in those taking placebo. However, there were no differences between groups in the actual value of visceral fat, changes in total fat or subcutaneous fat, BMI, body weight, abdominal circumference, or cholesterol or triglyceride levels (105298).
• Oral mucositis. Although there is interest in using oral rutin for oral mucositis, there is insufficient reliable information about the clinical effects of rutin for this condition.
• Osteoarthritis. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a specific combination product (Wobenzym PS, formerly Phlogenzym, Mucos Pharma) at a dose providing up to 600 mg rutin, 288 mg trypsin, and 540 mg bromelain daily for 3-12 weeks, is as effective as diclofenac for relieving pain and improving knee function in patients with painful osteoarthritis of the knee. This product also reduces the need for rescue medication by 95% when compared with placebo (6252,91104,99467,99477).
• Postoperative swelling. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small preliminary clinical study in patients undergoing surgery of the jaw shows that taking an enzyme combination of rutin 200 mg, trypsin 96 mg, and bromelain 180 mg twice daily for 5 days in addition to standard treatment reduces soft-tissue thickness (indicating the amount of swelling) at most of the nine assessed facial points when compared to control (99476).
• Sprains. Oral rutin has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A clinical study in patients with a sprained ankle shows that taking a specific enzyme combination (Phlogenzym, Mucos Pharma) containing rutin 100 mg, trypsin 48 mg, and bromelain 90 mg, or taking different combinations of the individual enzymes three times daily for 10 days, is no more effective for relieving pain than placebo (99473).
• Stroke. Although there is interest in using oral rutin for stroke prevention, there is insufficient reliable information about the clinical effects of rutin for this purpose.
• Sunburn. Although there is interest in using topical rutin for sunburn prevention, there is insufficient reliable information about the clinical effects of rutin for this purpose.
• Varicose veins. Although there is interest in using oral rutin for varicose veins, there is insufficient reliable information about the clinical effects of rutin for this condition. More evidence is needed to rate rutin for these uses.

(Read more about RUTIN)

There is insufficient reliable information available about the safety of caffeic acid.

PREGNANCY AND LACTATION:
Insufficient reliable information; avoid using.

(Read more about CAFFEIC ACID)

LIKELY SAFE ...when used orally in amounts found in foods.

POSSIBLY SAFE ...when supplements are used orally and appropriately, short-term. Diosmin seems to be safe when used alone or in combination with other flavonoids in doses of up to 1350 mg daily for up to 6 months (4861,4898,10227,10229,93885,105283,105286,105287,105293,105294)(105296,108150).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts found in foods.

PREGNANCY AND LACTATION: POSSIBLY SAFE
when used orally in doses of up to 900 mg daily for 30 days in combination with other flavonoids, such as hesperidin. Some evidence suggests that taking this combination may be associated with placental insufficiency when used during the third trimester of pregnancy; however, the combination does not seem to induce fetal abnormalities, retard fetal growth, increase the risk of intrauterine death, or affect birth weight. Also, when breastfeeding, this combination does not seem to affect infant growth or feeding (54970).

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POSSIBLY SAFE ...when used orally and appropriately, short-term. Quercetin has been used with apparent safety in doses up to 1 gram daily for up to 12 weeks (481,1998,1999,16418,16429,16430,16431,96774,96775,96782)(99237,102539,102540,102541,104229,104679,106498,106499,107450,109620)(109621). ...when used intravenously and appropriately. Quercetin has been used with apparent safety in doses less than 945 mg/m2. Higher doses have been reported to cause nephrotoxicity (9564,16418). There is insufficient reliable information available about the safety of quercetin when used topically.

POSSIBLY UNSAFE ...when used intravenously in large amounts. Doses greater than 945 mg/m2 have been reported to cause nephrotoxicity (9564,16418).

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about QUERCETIN)

LIKELY SAFE ...when used orally in amounts found in foods, such as fruits and vegetables.

POSSIBLY SAFE ...when used orally in medicinal amounts, short-term. Rutin has been used with apparent safety at doses of up to 600 mg daily for up to 12 weeks (6252,24560,91104,96766,105298). ...when applied topically as a cream (92236,99258,99260).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts commonly found in foods. There is insufficient reliable information available about the use of supplemental rutin; avoid amounts greater than those found in foods.

(Read more about RUTIN)

LEVODOPA Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeic acid might increase the levels and clinical effects of levodopa.  Details In an animal model, caffeic acid 10 mg/kg seems to significantly decrease conversion of levodopa to 3-O-methyldopa by about 22%. Caffeic acid also decreased the maximum concentration (Cmax) of 3-O-methyldopa by about 31% (18044). There is speculation that this interaction could be beneficial for Parkinson disease patients. However, the clinical significance of this potential interaction in humans is not known.

ORGANIC ANION TRANSPORTER 1 (OAT1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeic acid might increase the levels and clinical effects of OAT1 substrates.  Details In vitro, caffeic acid inhibits OAT1. This drug transport protein is involved in renal tubular uptake of some drugs from the blood and then elimination in the urine. Inhibition of this transporter decreases renal elimination and increases drug levels in the body (18041). Although caffeic acid inhibits OAT1 in vitro, the clinical significance of this in humans is not known.

ORGANIC ANION TRANSPORTER 3 (OAT3) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeic acid might increase the levels and clinical effects of OAT3 substrates.  Details In vitro, caffeic acid inhibits OAT3. This drug transport protein is involved in renal tubular uptake of some drugs from the blood and then elimination in the urine. Inhibition of this transporters decreases renal elimination and increases drug levels in the body (18041). Although caffeic acid inhibits OAT3 in vitro, the clinical significance of this in humans is not known.

(Read more about CAFFEIC ACID)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, diosmin may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details A case of spontaneous intraventricular hemorrhage has been reported for a 77-year-old female after 6 weeks of warfarin therapy, despite an international normalized ratio (INR) of only 1.8. The patient had also been taking aspirin and diosmin for several years. Experts speculate that chronic intake of diosmin predisposed the patient to spontaneous intraventricular hemorrhage by inducing chronic microcirculatory hypertension and inhibiting platelet aggregation. The presence of aspirin was also thought to play a role in this event (93886).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, diosmin might reduce the effects of carbamazepine and increase the risk for convulsions.  Details A pharmacokinetic study in humans shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of carbamazepine 200 mg increases blood levels of carbamazepine by approximately 58% and decreases carbamazepine clearance by 42%. It also decreases the formation of carbamazepine's active metabolite. It is speculated that diosmin reduces the metabolism of carbamazepine by inhibiting cytochrome P450 3A4 (CYP3A4) (95041).

CHLORZOXAZONE (Parafon Forte, Paraflex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, diosmin might increase the levels and clinical effects of chlorzoxazone.  Details A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of chlorzoxazone 250 mg increases blood levels of chlorzoxazone by 53% and decreases chlorzoxazone clearance by 40%. It is speculated that diosmin reduces the metabolism of chlorzoxazone by inhibiting cytochrome P450 2E1 (CYP2E1) (93889).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, diosmin might inhibit the metabolism of CYP2C9 substrates.  Details Diclofenac is metabolized by CYP2C9 enzymes. Clinical and laboratory research shows that diosmin inhibits the metabolism of diclofenac (93888,98596). A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of diclofenac 100 mg increases blood levels of diclofenac and decreases diclofenac clearance (93888).

CYTOCHROME P450 2E1 (CYP2E1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, diosmin might inhibit the metabolism of CYP2E1 substrates.  Details Chlorzoxazone is metabolized by CYP2E1 enzymes. A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of chlorzoxazone (Paraflex 250) 250 mg increases blood levels of chlorzoxazone by 34% and decreases chlorzoxazone clearance by 40%. It is speculated that diosmin reduces the metabolism of chlorzoxazone by inhibiting CYP2E1 (93889).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, diosmin might inhibit the metabolism of CYP3A4 substrates.  Details Laboratory research is conflicting with respect to the effects of diosmin on CYP3A4. Some research suggests that diosmin does not affect CYP3A4 activity (95040). However, other research suggests that diosmin alters the metabolism of carbamazepine, a CYP3A4 substrate. Laboratory and animal research show that oral administration of diosmin for 7 days prior to oral administration of carbamazepine increases plasma concentrations of carbamazepine, decreases the clearance of carbamazepine, and decreases the formation of carbamazepine's active metabolite (95039). Additionally, pharmacokinetic research in healthy male subjects shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of carbamazepine 200 mg increases blood levels of carbamazepine by approximately 58% and decreases carbamazepine clearance by 42% (95041). It is speculated that diosmin reduces the metabolism of carbamazepine by inhibiting CYP3A4 (95039,95041). Diosmetin, a metabolite of diosmin, may also inhibit CYP3A4 (95041).

DICLOFENAC (Voltaren, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, diosmin might increase the levels and clinical effects of diclofenac.  Details Clinical and laboratory research shows that diosmin inhibits the metabolism of diclofenac (93888,98596). A pharmacokinetic study in humans shows that taking diosmin (Venex 500) 500 mg daily for 9 days prior to oral administration of diclofenac 100 mg increases blood levels of diclofenac and decreases diclofenac clearance. It is speculated that diosmin reduces the metabolism of diclofenac by inhibiting cytochrome P450 2C9 (CYP2C9) (93888).

FEXOFENADINE (Allegra) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, diosmin might increase the levels and clinical effects of fexofenadine.  Details A pharmacokinetic study in humans shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of fexofenadine 120 mg increases blood levels of fexofenadine by approximately 49% and decreases the apparent oral clearance of fexofenadine by 41%. The time taken to reach maximum plasma concentration, the half-life, and the apparent renal clearance of fexofenadine are not affected. For this reason, it is speculated that diosmin alters the pharmacokinetics of fexofenadine via inhibition of P-glycoprotein in the intestine, but not in the kidney or liver (95042).

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, diosmin might increase levels of drugs that are substrates of P-glycoprotein (P-gp).  Details Preliminary laboratory research suggests that diosmin inhibits P-gp (93890). Additionally, pharmacokinetic research in healthy male subjects shows that taking diosmin (Venex) 500 mg daily for 10 days prior to oral administration of fexofenadine 120 mg increases blood levels of fexofenadine, a P-gp substrate, by approximately 49% and decreases the apparent oral clearance of fexofenadine by 41%. The time taken to reach maximum plasma concentration, the half-life, and the apparent renal clearance of fexofenadine are not affected. For this reason, it is speculated that diosmin inhibits P-gp in the intestine, but not in the kidney or liver (95042).

(Read more about DIOSMIN)

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use of quercetin and antidiabetes drugs might increase the risk of hypoglycemia.  Details Clinical research suggests that a combination of quercetin, myricetin, and chlorogenic acid reduce levels of fasting glucose in patients with type 2 diabetes, including those already taking antidiabetes agents (96779). The effect of quercetin alone is unknown.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking quercetin with antihypertensive drugs might increase the risk of hypotension.  Details Quercetin can modestly decrease blood pressure in people with mild hypertension (16424,96780). Theoretically, it might have additive blood pressure lowering effects when used with antihypertensive drugs.

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of cyclosporine.  Details A small study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine, possibly due to inhibition of p-glycoprotein or cytochrome P450 3A4 (CYP3A4), which metabolizes cyclosporin (16434).

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of CYP2C8 substrates.  Details In vitro research shows that quercetin inhibits CYP2C8 (16432,16435). Inhibition of paclitaxel (Taxol) metabolism via CYP2C8 has been reported in vitro (16436). However, a small study in humans found no effect of quercetin on rosiglitazone (Avandia), which is also a CYP2C8 substrate (16432).

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of CYP2C9 substrates.  Details A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac, a CYP2C9 substrate, increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5% (97931). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar), a substrate of CYP2C9 (100968). Furthermore, laboratory research shows that quercetin inhibits CYP2C9 (15549,16433).

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.  Details In vitro research show that quercetin inhibits CYP2D6 (15549,16433). This effect has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might alter the effects and adverse effects of CYP3A4 substrates.  Details A small clinical study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine (Neoral, Sandimmune), a substrate of CYP3A4 (16434). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) and quetiapine (Seroquel), substrates of CYP3A4 (100968,104228). Other laboratory research also shows that quercetin inhibits CYP3A4 (15549,16433,16435). However, one clinical study shows that quercetin can increase the metabolism of midazolam, a substrate of CYP3A4, and decrease serum concentrations of midazolam by about 24% in some healthy individuals, suggesting possible induction of CYP3A4 (91573).

DICLOFENAC (Voltaren, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the levels and adverse effects of diclofenac.  Details A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5%. This is thought to be due to inhibition of CYP2C9 by quercetin (97931).

LOSARTAN (Cozaar) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of losartan and decrease the effects of its active metabolite.  Details Animal research shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) while decreasing plasma levels of losartan's active metabolite. This metabolite, which is around 10-fold more potent than losartan, is the result of cytochrome P450 (CYP) 2C9- and CYP3A4-mediated transformation of losartan. Additionally, in vitro research shows that quercetin may inhibit P-glycoprotein-mediated efflux of losartan from the intestines, resulting in increased absorption of losartan (100968). These results suggest that concomitant use of quercetin and losartan might increase systemic exposure to losartan while also decreasing plasma concentrations of losartan's active and more potent metabolite.

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might decrease the levels and effects of midazolam.  Details A small clinical study in healthy volunteers shows that quercetin can increase the metabolism of midazolam, with a decrease in AUC of about 24% (91573).

MITOXANTRONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of mitoxantrone.  Details In vitro research shows that quercetin increases the intracellular accumulation and cytotoxicity of mitoxantrone, possibly through inhibition of breast cancer resistance protein (BCRP), of which mitoxantrone is a substrate (107897). So far, this interaction has not been reported in humans.

ORGANIC ANION TRANSPORTER 1 (OAT1) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of OAT1 substrates.  Details In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT1, with half-maximal inhibitory concentration (IC50) values less than 10 mcM (104454). So far, this interaction has not been reported in humans.

ORGANIC ANION TRANSPORTER 3 (OAT3) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.  Details In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT3, with half-maximal inhibitory concentration (IC50) values as low as 0.75 mcM (104453,104454). So far, this interaction has not been reported in humans.

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of OATP substrates.  Details In vitro evidence shows that quercetin can inhibit organic anion-transporting peptide (OATP) 1B1-mediated uptake of estrone-3-sulfate and pravastatin (91581). Furthermore, clinical research in healthy males shows that intake of quercetin along with pravastatin increases the AUC of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581).

P-GLYCOPROTEIN SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might alter the effects and adverse effects of P-glycoprotein substrates.  Details There is preliminary evidence that quercetin inhibits the gastrointestinal P-glycoprotein efflux pump, which might increase the bioavailability and serum levels of drugs transported by the pump (16433,16434,16435,100968,104228). A small study in healthy volunteers reported that pretreatment with quercetin increased bioavailability and plasma levels after a single dose of cyclosporine (Neoral, Sandimmune) (16434). Also, two small studies have shown that quercetin might decrease the absorption of talinolol, a substrate transported by the gastrointestinal P-glycoprotein efflux pump (91579,91580). However, in another small study, several days of quercetin treatment did not significantly affect the pharmacokinetics of saquinavir (Invirase) (16433). The reason for these discrepancies is not entirely clear (91580). Until more is known, use quercetin cautiously in combination with P-glycoprotein substrates.

PRAVASTATIN (Pravachol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of pravastatin.  Details In vitro evidence shows that quercetin can inhibit OATP 1B1-mediated uptake of pravastatin (91581). Also, preliminary clinical research in healthy males shows that intake of quercetin along with pravastatin increases the maximum concentration of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581).

PRAZOSIN (Minipress) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of prazosin.  Details In vitro research shows that quercetin inhibits the transcellular efflux of prazosin, possibly through inhibition of breast cancer resistance protein (BCRP), of which prazosin is a substrate. BCRP is an ATP-binding cassette efflux transporter in the intestines, kidneys, and liver (107897). So far, this interaction has not been reported in humans.

QUETIAPINE (Seroquel) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the effects and adverse effects of quetiapine.  Details Animal research shows that pretreatment with quercetin can increase plasma levels of quetiapine and prolong its clearance, possibly due to inhibition of cytochrome P450 3A4 (CYP3A4) by quercetin. Additionally, the brain-to-plasma ratio of quetiapine concentrations increased, possibly due to inhibition of P-glycoprotein at the blood-brain barrier (104228). This interaction has not been reported in humans.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, concomitant use might inhibit the effects of quinolone antibiotics.  Details In vitro, quercetin binds to the DNA gyrase site on bacteria (481), which may interfere with the activity of quinolone antibiotics.

SULFASALAZINE (Azulfidine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin might increase the effects and adverse effects of sulfasalazine.  Details Animal research shows that quercetin increases the maximum serum concentration (Cmax) and area under the curve (AUC) of sulfasalazine, possibly through inhibition of breast cancer resistance protein (BCRP), of which sulfasalazine is a substrate (107897). So far, this interaction has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, quercetin may increase the risk of bleeding if used with warfarin.  Details Animal and in vitro studies show that quercetin might increase serum levels of warfarin (17213,109619). Quercetin and warfarin have the same human serum albumin (HSA) binding site, and in vitro research shows that quercetin has stronger affinity for the HSA binding site and can theoretically displace warfarin, causing higher serum levels of warfarin (17213). Animal research shows that taking quercetin for 2 weeks before initiating warfarin increases the maximum serum level of warfarin by 30%, the half-life by 10%, and the overall exposure by 63% when compared with control. Concomitant administration of quercetin and warfarin, without quercetin pre-treatment, also increased these measures, but to a lesser degree. Researchers theorize that inhibition of CYP3A4 by quercetin may explain these effects (109619). So far, this interaction has not been reported in humans.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking rutin with antidiabetes drugs might increase the risk of hypoglycemia.  Details Animal research suggests that rutin has hypoglycemic effects (105299).

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General ...No adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

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General ...Orally, diosmin is generally well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, dizziness, gastritis, nausea, skin inflammation, and skin redness.
Serious Adverse Effects (Rare):
Orally: Cardiac arrhythmias and hemolytic anemia.

Cardiovascular ...Orally, diosmin can cause cardiac arrhythmias (93887,105293).

Dermatologic ...Orally, diosmin can cause skin redness, hives, itchiness, and inflammation (93887).

Gastrointestinal ...Orally, diosmin can cause gastrointestinal side effects, including abdominal pain, diarrhea, nausea, flatulence, and gastritis (4861,4898,4900,10229,54935,54970,93887,105287,105293,105296)(112796). In one case, exacerbation of chronic colopathy was reported after taking a specific diosmin-containing product (Daflon 500, Les Laboratoires Servier) (10229).

Hematologic ...Orally, diosmin can cause hemolytic anemia (93887).

Musculoskeletal ...Orally, one case report of muscle pain was thought to be related to diosmin use (93887).

Neurologic/CNS ...Orally, diosmin can cause headache, low energy, and dizziness in some patients (4861,4898,4900,10229,93887,105293,112796).

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General ...Orally and intravenously, quercetin seems to be well tolerated in appropriate doses. Topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

Gastrointestinal ...Intravenous administration of quercetin is associated with nausea and vomiting (9564).

Neurologic/CNS ...Orally, quercetin may cause headache and tingling of the extremities (481,111500). Intravenously, quercetin may cause pain at the injection site. Injection pain can be minimized by premedicating patients with 10 mg of morphine and administering amounts greater than 945 mg/m² over 5 minutes (9564). In addition, intravenous administration of quercetin is associated with flushing and sweating (9564).

Pulmonary/Respiratory ...Intravenous administration of quercetin at doses as high as 2000 mg/m² is associated with dyspnea that may persist for up to 5 minutes (9564).

Renal ...Intravenously, nephrotoxicity has been reported with quercetin in amounts greater than 945 mg/m² (9563,9564,70304).

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General ...Orally, rutin is generally well tolerated.

Dermatologic ...Orally, rutin may cause flushing and rashes in some people (313).

Gastrointestinal ...Orally, rutin may cause gastrointestinal disturbance in some people (313).

Neurologic/CNS ...Orally, rutin may cause headache in some people (313).

(Read more about RUTIN)