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POSSIBLY EFFECTIVE

• Acne. Topical black seed extract hydrogel seems to improve acne. Details: In patients with mild to moderate acne, clinical research shows that topical application with a hydrogel containing black seed extract 0.1% twice daily for 60 days reduces the number of comedones, papules, and pupules by a large amount when compared with placebo. The overall improvement, as rated by a physician, was 78% for the black seed extract hydrogel, compared with 3% for the placebo gel (101551).
• Allergic rhinitis (hay fever). Oral black seed oil seems to reduce symptoms of allergic rhinitis over 4-8 weeks. It is unclear if black seed is beneficial long-term. Details: Clinical research shows that taking capsules containing black seed oil 0.5 mL daily for 1 month can reduce symptoms such as itching, nasal congestion, sneezing, and runny nose when compared with placebo in adults with allergic rhinitis (95989). Other preliminary clinical research shows that taking a specific product containing black seed oil 500 mg (Immerfit, Phyt-Immun) for a total dose of 40-80 mg/kg orally daily for 4-8 weeks improves patient-scored symptoms of allergic rhinitis in 81% of patients, compared to 45% of patients taking placebo (36071). More research is needed to determine if black seed is beneficial long-term and how it compares to conventional allergy medications.
• Asthma. Oral black seed seems to be beneficial for symptoms like wheezing and coughing and might improve lung function measures in patients with poor pulmonary function. Details: Some clinical research shows that taking black seed extract for 3 months can improve symptoms such as wheezing and coughing when compared with placebo in patients with moderate to severe asthma who already take conventional asthma medication (36175). Other research shows that taking black seed oil (Cuminmar, Marnys) 500 mg twice daily for 4 weeks can improve self-reported asthma control and daily functioning when compared with placebo in adults with inadequately controlled asthma despite using maintenance inhalers (95987). The effects of black seed on pulmonary function are conflicting. Some research shows that taking black seed can improve lung function measures such as forced expiratory flow (36175,36280,94490,101556), while other research shows no significant benefit (95987,101556). Doses used in studies showing benefit include ground black seed 2 grams daily for 12 weeks, black seed extract 15 mL/kg daily for 3 months, or a single dose of 50-100 mg/kg (36175,36280,94490). Differing findings may relate to pulmonary function at baseline. Taking black seed extract or black seed oil seems to improve pulmonary function in patients with abnormally low pulmonary function at baseline, but not those with predicted forced expiratory volume in 1 second (FEV1) of at least 80% (36175,95987). Also, single doses of black seed extract do not appear to improve pulmonary function as effectively as bronchodilators such as theophylline or salbutamol (36280).
• Chronic obstructive pulmonary disease (COPD). Oral black seed seems to improve lung function measures in patients with COPD using inhaled corticosteroids. Details: In middle-aged adults undergoing routine treatment with inhaled corticosteroids for COPD, clinical research shows that taking black seed oil (Amazing Herbs) 1 gram twice daily for 3 months improves pulmonary function tests by a small to moderate amount when compared with placebo (104663).
• Diabetes. Oral black seed powder in doses of at least 2 grams daily or black seed oil 1 gram daily seem to improve glucose control in patients with type 2 diabetes. Details: One clinical study shows that taking black seed powder 1 gram twice daily for 3-12 months improves glycated hemoglobin (HbA1c) and decreases fasting blood glucose by 17% to 26% when compared to baseline in patients with diabetes who are already using antidiabetes medications (94479,94485). These improvements were significant when compared with placebo at 3 months and 9 months, but not at 12 months (94485). Clinical research also shows that taking black seed powder 1 gram twice daily also improves levels of total cholesterol by 10% to 12% when compared with placebo in patients with diabetes (94478); a lower dose of 1 gram daily does not seem to be beneficial (94479). The effect of black seed oil has also been investigated. Clinical research shows that taking black seed oil 450 mg three times daily for 12 weeks decreases fasting blood glucose by around 14 mg/dL and HbA1c by 0.3% in patients with newly diagnosed diabetes when compared with baseline. However, these improvements were inferior to those reported in patients taking metformin 2000 mg daily (102062). Other clinical research shows that taking black seed oil 1 gram daily for 8 weeks decreases fasting blood glucose by 23.0 mg/dL and HbA1c by 0.69% from baseline. These changes, as well as reductions in low-density lipoprotein (LDL) cholesterol, triglycerides, and systolic and diastolic blood pressure were significant when compared with placebo (110269). Other clinical research also shows that taking black seed oil 1 gram daily for 8 weeks reduces fasting blood glucose, triglyceride, and low-density lipoprotein (LDL) cholesterol levels when compared with placebo. However, baseline levels for each of these parameters were higher in the treatment group when compared with the placebo group, raising concerns about the validity of these findings (101552). The black seed constituent thymoquinone has also been investigated in clinical research. Clinical research in patients with type 2 diabetes shows that taking thymoquinone 50 mg or 100 mg daily in addition to metformin 1 gram daily for 90 days increases the number of patients with HbA1c levels of less than 7.0% when compared with metformin alone. However, it is unclear if fasting blood glucose levels are further reduced (110270).
• Helicobacter pylori. Oral black seed 2 grams daily seems to improve H. pylori eradication when used in combination with standard therapies. Details: Clinical research shows that in patients receiving quadruple therapy with metronidazole, amoxicillin, bismuth subcitrate, and omeprazole, the eradication of H. pylori occurred in 88% of patients receiving quadruple therapy plus black seed powder 1 gram twice daily for 8 weeks, compared with 55% of patients taking quadruple therapy alone. Quality of life was also improved (101555). Clinical research also shows that taking black seed powder (BioExtract Ltd) 2 grams daily along with omeprazole 40 mg daily for 4 weeks produces H. pylori eradication in 67% of patients, compared to 83% of patients taking standard triple therapy with clarithromycin, amoxicillin, and omeprazole taken for 1 week. However, this study also found that taking black seed powder 1 gram or 3 grams daily along with omeprazole was less effective than standard triple therapy (95980). The reasons for this discrepancy are unclear.
• Hypertension. Oral black seed powder and black seed oil seem to reduce blood pressure by a small amount. However, if it is unclear if taking black seed is beneficial in patients with hypertension. Details: A pooled analysis of results from small clinical studies in patients with or without hypertension shows that taking black seed powder 0.5-2 grams daily or black seed oil up to 3 grams daily for 4-12 weeks reduces systolic and diastolic blood pressure by about 3 mmHg when compared with placebo (94489). Only one of the studies included in the analysis investigated the effect of black seed in males with hypertension. This small study showed that taking black seed oil 100-200 mg twice daily for 8 weeks modestly reduces systolic and diastolic blood pressure by about 2 mmHg (16437). Another study in the analysis that included patients with or without hypertension found that taking black seed oil 2.5 mL twice daily after meals for 8 weeks reduces systolic and diastolic blood pressure by about 11 mmHg and 10 mmHg, respectively, when compared with baseline (96929).
• Male infertility. Oral black seed oil seems to improve sperm quality and function. It is unclear if this increases the rate of successful pregnancies. Details: Clinical research shows that taking black seed oil 2.5 mL twice daily for 2 months improves sperm count by 40%, sperm morphology by 32%, and sperm motility by 13% when compared with placebo in infertile males (94486).
• Mastalgia. Topical black seed oil seems to reduce breast pain. Details: Clinical research shows that applying 2 grams of gel containing 30% black seed oil at the site of pain twice daily for two menstrual cycles reduces breast pain by about 82% when compared to baseline. This improvement is similar to diclofenac gel and significantly greater than placebo gel, which reduces pain by only 18% (94483).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Anthracycline cardiotoxicity. It is unclear if oral black seed oil reduces cardiac toxicity associated with doxorubicin treatment. Details: Preliminary clinical research in children aged 2-16 years with acute lymphoblastic leukemia shows that taking black seed oil 80 mg/kg in three divided doses daily for one week, starting with each doxorubicin infusion therapy, is protective against some, but not most, measures of cardiac toxicity associated with doxorubicin. However, it is unclear if any of these changes are associated with clinically meaningful improvements in outcome (101554).
• Atopic dermatitis (eczema). It is unclear if oral or topical black seed oil is beneficial for reducing symptoms of atopic dermatitis. Details: One small study reports that using 15% black seed oil ointment topically for 4 weeks does not improve disease severity, pruritus, or hydration in patients with atopic dermatitis (36316). Other preliminary clinical research shows that taking a specific product containing black seed oil 500 mg (Immerfit, Phyt-Immun) for a total dose of 40-80 mg/kg daily for 4-8 weeks improves subjective patient-scored symptoms of atopic dermatitis in 50% of patients when compared to baseline (36071).
• Autoimmune thyroiditis. It is unclear if oral black seed is beneficial for patients with autoimmune thyroiditis. Details: Clinical research in patients with Hashimoto's thyroiditis shows that taking black seed powder 2 grams daily for 8 weeks increases thyroid stimulating hormone levels by 36% and anti-thyroid peroxidase (anti-TPO) antibody levels by 50% when compared to baseline; these improvements are significant when compared with placebo. However, black seed powder does not improve thyroxine or triiodothyronine levels when compared with placebo (94481).
• Cancer. Although there is interest in using oral black seed for cancer, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Cardiovascular disease (CVD). It is unclear if oral black seed is beneficial for patients with coronary artery disease. Details: A small clinical trial shows that taking black seed oil 2 grams daily for 8 weeks reduces systolic and diastolic blood pressure by 9.52 mm Hg and 8.26 mm Hg, respectively, when compared with placebo. Fasting blood glucose, body mass index, and waist and hip circumferences were also modestly reduced. There was no effect on other glycemic indices. There was also no effect on blood lipids; however, most patients were taking statins (110276).
• Chemotherapy-induced lymphocytopenia. It is unclear if oral black seed is beneficial for preventing febrile neutropenia. Details: Preliminary clinical research in children undergoing chemotherapy for brain tumors shows that taking whole or ground black seed 5 grams daily as part of the diet for 3-9 months of chemotherapy reduces the incidence of febrile neutropenia episodes by 88% when compared with placebo. To prevent one case of febrile neutropenia, six patients would need to be treated with black seed. The duration of hospital stay was also reduced by 2.5 days when compared with placebo (96931).
• Chemotherapy-induced phlebitis. It is unclear if oral black seed is beneficial for reducing the severity of phlebitis in patients receiving intravenous chemotherapy. Details: Preliminary clinical research in cancer patients receiving intravenous chemotherapy shows that applying 5 drops of black seed oil around the peripheral vein catheter twice daily for 3 days decreases phlebitis severity and reduces the relative risk of phlebitis at 72 hours by 35% when compared with no treatment. These results suggest that for every 3 patients treated with black seed oil for 3 days, one additional case of phlebitis will be prevented (102060).
• Chronic kidney disease (CKD). It is unclear if oral black seed oil is beneficial for patients with CKD. Details: Preliminary clinical research in patients with stages 3 and 4 CKD shows that taking black seed oil (Kalonji oil, Mohammedia products) 2.5 mL once daily for 12 weeks as add-on therapy with alpha-keto analogues of essential amino acids improves measures of kidney function by a small amount when compared with taking the alpha-keto analogues alone (101550).
• Cognitive function. Oral black seed might improve some measures of memory or cognitive function. Details: Clinical research in a small group of adolescent males shows that taking crushed black seed 500 mg daily for 4 weeks improves some measures of short-term or long-term recall when compared with placebo (96915). Other clinical research in a small group of middle-aged men shows that taking black seed 500 mg twice daily for 9 weeks improves some measures of memory, attention, and cognitive function when compared with placebo (96928). The improvements in both studies appear to be modest, so the clinical significance is unclear.
• Constipation. Although there is interest in using oral black seed for constipation, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Contraception. Although there is interest in using oral black seed for contraception, there is insufficient reliable information about the clinical effects of black seed for this purpose.
• Coronavirus disease 2019 (COVID-19). It is unclear if oral black seed is beneficial for patients with COVID-19. Details: Preliminary clinical research in patients with mild COVID-19 shows that taking black seed oil (Marnys Cuminmar) 500 mg twice daily for 10 days results in recovery by day 14, defined as freedom of symptoms lasting three days, in 62% of patients, compared with 36% of those patients not given black seed oil. Also, the duration to recovery was reduced by 1.6 days (110267). Also, preliminary clinical research in patients with mild to moderate COVID-19 shows that taking black seed (Baraka, Pharco Pharmaceuticals, Cairo, Egypt) 900 mg twice daily for 14 days modestly reduced the severity of some symptoms, including cough, diarrhea, fatigue, and pharyngitis, as well as the percent patients with viral positivity at day 7, when compared to standard care alone. Similar findings occurred when black seed was taken with vitamin D3 (Davalindi, Medical Union Pharma, Cairo, Egypt) 2,000 IU daily (110265). These studies are limited by a lack of placebo and blinding. In contrast to these findings, clinical research in patients with mild or asymptomatic COVID-19 does not show that taking black seed for 10 days has beneficial effects on symptoms or inflammatory markers when compared with charcoal as control. The black seed form in this study varied between whole seeds and powder, as well as the number (two to nine) of capsules taken in divided doses daily (110271). Black seed oil has also been investigated in combination with other compounds. Preliminary clinical research in patients with moderate to severe COVID-19 given standard care shows that taking black seed powder 80 mg/kg daily in combination with raw honey 1 gram/kg daily for 13 days reduces the time to alleviate symptoms by approximately 50%, and the time to clear virus by about 35%, when compared with placebo capsules and no honey. In patients with moderate symptoms, 63.6% had resumed normal activity within 6 days when compared with 10.9% of those taking placebo. In patients with severe symptoms, 50% were discharged from hospital by day 6 compared with 2.8% of those taking placebo, and the mortality rate was reduced by approximately 79% (110261). It is not clear if any beneficial effects are due to black seed, honey, or the combination.
• Diarrhea. Although there is interest in using oral black seed for diarrhea, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Dysmenorrhea. It is unclear if topical black seed oil reduces menstrual pain. Details: Clinical research shows that topical application of black seed oil (Barij Essence Company) 1-2 drops to the fontanel lobe of the head each night for up to 8 days, starting three days before menstruation, for three menstrual cycles modestly reduces menstrual pain when compared with olive oil (104662). It is unclear if any benefits are clinically significant.
• Dyspepsia. Oral black seed oil has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a 1:1:1 mixture of a black seed oil, honey, and water orally for 2 months improves overall symptoms of dyspepsia by approximately 43%, compared to only 10% in the placebo group (94487).
• Epilepsy. It is unclear if oral black seed is beneficial for patients with epilepsy. Details: Some preliminary clinical research in children aged 13 months to 13 years with epilepsy shows that taking black seed extract 40 mg/kg every 8 hours for 4 weeks reduces the frequency of seizures in 65% of, compared to only 20% of patients taking placebo (36180). Other preliminary clinical research in children 2-16 years of age with epilepsy shows that taking black seed oil 40-80 mg/kg daily does not reduce seizure frequency or severity when compared with placebo (94491). It is possible that there is a constituent found in the extract, and absent in the oil, that is responsible for any anti-seizure effects of black seed.
• Gingivitis. It is unclear if topical black seed is beneficial for patients with gingivitis. Details: In patients with moderate to severe gingivitis, preliminary clinical research shows that topical application of black seed extract for three days reduces gingival swelling and redness by a moderate amount, and plaque by a small amount, when compared to baseline. However, it is less effective than scaling and root planing (104664).
• Hemorrhoids. Although there is interest in using oral black seed for hemorrhoids, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Hepatitis C. It is unclear if oral black seed is beneficial for patients with hepatitis C. Details: Preliminary clinical research shows that taking black seed oil (Baraka, Pharco Pharmaceuticals) 450 mg three times daily for 3 months reduces hepatitis C viral load in 67% of patients, improves lower limb edema, and modestly increases total protein and albumin levels when compared to baseline; however, no improvement is seen in Child-Pugh score or other measures of liver function, including bilirubin, liver enzymes, or INR (95986). The validity of these findings is limited by the lack of a control group.
• HIV/AIDS. Although there is interest in using oral black seed for HIV/AIDS, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Hyperlipidemia. It is unclear if oral black seed is beneficial for patients with hyperlipidemia. Details: Some preliminary clinical research shows that taking whole crushed black seed 1 gram twice daily or black seed powder 1 gram daily for 4-8 weeks reduces total cholesterol by 5% to 16%, low-density lipoprotein (LDL) cholesterol by 8% to 27%, and triglycerides by 17% to 22% when compared to baseline in these patients; these improvements are significantly greater than changes in the placebo group (18221,94484). The effect of black seed when used in combination with statins shows conflicting results. One clinical study shows that taking black seed powder 1 gram twice daily for 6 weeks does not decrease cholesterol levels when compared with statins alone in normocholesterolemic, borderline hypercholesterolemic, or hypercholesterolemic patients (36244). Other clinical research in adults with hypercholesterolemia shows that taking whole crushed black seed 500 mg, garlic oil 250 mg, and simvastatin 10 mg daily for 8 weeks produces a larger increase in high-density lipoprotein (HDL) cholesterol and a greater reduction in total cholesterol, LDL cholesterol, and triglycerides when compared with simvastatin 10 mg daily alone (95985). Reasons for these conflicting results may relate to the black seed dose or formulation and the cholesterol levels of the included patients at baseline. Taking whole crushed black seed 1 gram twice daily for 8 weeks in conjunction with aerobic training does not appear to improve LDL cholesterol, total cholesterol, or triglyceride levels when compared with aerobic training alone in females with hypercholesterolemia; however, it appears to modestly increase HDL cholesterol levels (95983).
• Impaired glucose tolerance (prediabetes). It is unclear if oral black seed oil is beneficial for patients with prediabetes. Details: Preliminary clinical research in obese patients with prediabetes shows that taking black seed oil (Baraka450; Pharco Pharmaceutical Company) 450 mg twice daily for 6 months improves most anthropometric, lipid, and glycemic parameters when compared with baseline. Also, most improvements are similar to changes following the use of metformin 500 mg twice daily or following a controlled diet and exercise regimen (110275).
• Influenza. Although there is interest in using oral black seed for influenza, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Insomnia. Although there is interest in using oral black seed oil for insomnia, there is insufficient reliable information about the clinical effects of black seed oil for this condition.
• Lichen planus. It is unclear if topical black seed oil is beneficial for patients with oral lichen planus. Details: Clinical research in patients with oral lichen planus shows that topical application with cream containing black seed oil (Greenish Baraka black seed oil, Greenish India Pvt. Ltd., Chennai) 75% twice daily after meals for 45 days is as effective as gel containing clobetasol propionate 0.05% for reducing lesion size and burning severity (110263). This study is limited by the lack of inclusion of a placebo-controlled group.
• Menopausal symptoms. Oral black seed has only been evaluated in combination with other ingredients; its effect when used alone is unclear. It is unclear if topical black seed oil is beneficial for menopausal symptoms. Details: Preliminary clinical research in postmenopausal females shows that taking a combination of black seed and vitex agnus-castus daily for 8 weeks, in combination with citalopram 20 mg, improves vasomotor, psychosocial, and physical symptoms of menopause when compared with placebo and citalopram (100325). It is not clear if these effects are due to black seed, vitex agnus-castus, or the combination. Clinical research in postmenopausal females shows that topical application with 2-3 drops of black seed oil (Barij Essence Pharmaceutical Company, Kashan, Iran) on the lower abdomen twice daily for 8 weeks does not improve sexual function or quality of life related to menopause when compared with placebo (110262).
• Metabolic syndrome. It is unclear if oral black seed is beneficial for patients with metabolic syndrome. Details: Clinical research in patients with metabolic syndrome after menopause shows that taking black seed extract 500 mg daily for 8 weeks improves levels of fasting blood sugar by 23%, low-density lipoprotein (LDL) cholesterol by 12%, and triglycerides by 8% over baseline. These changes were significant when compared with placebo. However, taking black seed extract did not improve anthropometric measures when compared with placebo (101549). In addition, preliminary clinical research in patients with metabolic syndrome shows that taking a specific black seed oil product (Mohammedia Products, Hyderabad) 2.5 mL twice daily for 6 weeks decreases total cholesterol by 59%, LDL cholesterol by 50%, and fasting blood glucose by 58% over placebo (36262). The effects of this black seed oil product on other important parameters of metabolic syndrome, such as weight and blood pressure, were not reported in this study. In contrast, other clinical research shows that taking bread providing black seed powder 3 grams daily for 2 months does not have a significant effect on lipid profiles in patients with metabolic syndrome. Weight and waist circumference were not reported (104667).
• Methotrexate toxicity. It is unclear if oral black seed oil is beneficial for reducing toxicity associated with methotrexate treatment. Details: Preliminary clinical research shows that taking black seed oil (Baraka, Pharco Pharmaceuticals) 80 mg/kg orally in three divided doses daily for 1 week after each methotrexate dose prevents elevations in bilirubin and liver function enzymes when compared with placebo in children aged 4-13 years with acute lymphoblastic leukemia (95984).
• Nonalcoholic fatty liver disease (NAFLD). Research suggests that oral black seed or black seed oil modestly improves some metabolic and liver health parameters in patients with NAFLD. However, some studies are small, and research related to measures of steatosis, including liver biopsy and magnetic resonance imaging (MRI), is needed. Details: Clinical research in adults with NAFLD shows that taking black seed oil 2.5 mL twice daily for 3 months, or 1000 mg (Barij Essence Co., Iran) daily for 8 weeks, modestly increases high-density lipoprotein (HDL) cholesterol levels and reduces levels of liver function enzymes, low-density lipoprotein (LDL) cholesterol, and triglycerides when compared with placebo (100322,110282). These studies also show that taking black seed oil also modestly improves levels of fasting blood glucose (110282) and steatosis grade as measured by ultrasound (100322). In one study, both black seed oil capsule and placebo capsule also contained honey and water (100322). However, taking black seed oil does not seem to improve insulin levels (110282). The effect of black seed oil on blood pressure has also been investigated. Clinical research shows that taking black seed oil (Barij Black Seed Oil, Barij Essence Pharmaceutical Company, Kashan, Iran) 1000 mg daily for 8 weeks does not reduce systolic or diastolic blood pressure when compared with placebo (110274,110282). Black seed has also been investigated in small clinical trials in adults with NAFLD. One trial shows that taking black seed 2 grams daily for 12 weeks reduces glucose and insulin levels, improves measures of insulin sensitivity and resistance, and reduces hepatic steatosis percentage when compared with placebo. However, there was no improvement in fibrosis scores, steatosis grades, and levels of lipids and liver function enzymes (102061). Another trial shows that using the same dose of black seed powder results in large reductions in body weight and body mass index (BMI), as well as liver enzymes, when compared with placebo. Also, 57.1% of patients taking black seed had normal fatty liver grading on abdominal ultrasound, compared with 6% of those taking placebo (110268). The reasons for these disparate results are unclear. However, it is possible the studies were underpowered to detect differences in secondary outcomes. More research is needed using gold standard measures of steatosis, including liver biopsy and magnetic resonance imaging (MRI).
• Obesity. It is unclear if oral black seed is beneficial for increasing weight loss. Details: Meta-analyses of preliminary clinical research involving a total of 875 patients show that taking black seed oil 3-5 grams daily, black seed powder 0.1-3 grams daily, or black seed extract 100-200 mg daily for up to 13 weeks reduces body weight by about 2 kg and body mass index (BMI) by 0.85-1.2 kg/m2 when compared with placebo. It is unclear if these reductions are clinically significant. In addition, most studies in these meta-analyses do not involve patients with a BMI over 25 kg/m2 (96926,98815). Although some individual research shows that taking black seed powder 2 grams or black seed oil 3 grams daily for 8 weeks does not reduce BMI in overweight females who are also exercising or following a low-calorie diet (95983,96927), most individual studies show that black seed or black seed oil reduces body weight and waist circumference (95730,96927,104661,110269). One study shows that black seed has a moderate effect on weight loss, BMI, and waist circumference, and a small effect on total and visceral fat mass (104661). These studies have used black seed powder 1.5 grams twice daily for 3 months or black seed oil 2 or 3 grams daily for 8 weeks (95730,96927,104661). Reasons for the discrepancies may relate to concomitant use with dieting or exercise. It is unclear if taking black seed oil improves the lipid profile of individuals with a BMI of at least 25 kg/m2. One small clinical study shows that taking black seed oil 2 grams daily for 8 weeks has a small to moderate effect on levels of high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol when compared with placebo (104666). However, another study shows that although taking black seed oil 3 grams daily for 8 weeks reduces triglyceride levels more than placebo, there is no effect on HDL or LDL cholesterol levels (96927).
• Opioid withdrawal. It is unclear if oral black seed is beneficial for reducing symptoms of opioid withdrawal. Details: Preliminary clinical research shows that taking black seed powder 500 mg by mouth three times daily for 12 days decreases symptoms of opioid withdrawal by 70% to 77% when compared to baseline (36239). The validity of this finding is limited by the lack of a comparator group.
• Osteoarthritis. It is unclear if topical black seed oil is beneficial for knee osteoarthritis. Details: Preliminary clinical research shows that applying black seed oil 1 mL to the knee by massaging into the skin for 5 minutes three times daily for 3 weeks reduces pain when compared to baseline and produces a larger reduction in pain than acetaminophen 325 mg three times daily for 3 weeks (95981). Other clinical research shows that applying approximately 10 mL of black seed oil to the knees three times weekly for 1 month reduces pain severity when compared to baseline (98814). The validity of this finding is limited by the lack of a control group.
• Psoriasis. Although there is interest in using topical black seed for psoriasis, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Radiation dermatitis. It is unclear if topical black seed is beneficial for preventing dermatitis caused by radiotherapy. Details: Clinical research in breast cancer patients undergoing radiation treatment shows that applying a gel containing black seed extract providing thymoquinone 0.01% twice daily delays the incidence of radiation dermatitis and the onset of moist desquamation by 2-6 days when compared with placebo gel. However, there was no effect on the quality of life related to skin condition (101557).
• Rheumatoid arthritis (RA). It is unclear if topical black seed is beneficial for RA. Details: Preliminary clinical research shows that taking a specific brand of black seed oil (Nigellar, Kahira Pharmaceutical and Chemical Industries Company) 500 mg twice daily for one month improves symptoms of RA, such as pain, morning stiffness, and disease severity, when compared with placebo in patients who are already taking methotrexate (94482).
• Senile rhinitis. It is unclear if topical black seed is beneficial for patients with senile rhinitis. Details: The elderly population is particularly susceptible to symptoms of nasal dryness and irritation due to a reduction in mucus production. Preliminary clinical research shows that black seed oil given as 3 sprays into each nostril three times daily for 2 weeks can modestly improve symptoms of nasal dryness, obstruction, and crusting in this population when compared with sodium chloride nasal spray; however, there is no improvement in burning, itching, or nasal mucociliary clearance (95988).
• Tonsillopharyngitis. Oral black seed has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that the combination of chanca piedra 50 mg and black seed 360 mg, taken orally three times daily for 7 days, may relieve pain in patients with tonsillopharyngitis when compared with placebo (36199).
• Ulcerative colitis. It is unclear if oral black seed is beneficial for patients with ulcerative colitis. Details: Preliminary clinical research in adults with mild to moderate ulcerative colitis shows that taking black seed powder 2000 mg daily for 6 weeks does not improve disease activity scores or symptoms of ulcerative colitis when compared with placebo (100323).
• Urinary incontinence. It is unclear if topical black seed oil is beneficial for patients with urinary incontinence. Details: Clinical research in postmenopausal females with urinary incontinence shows that topical application with 2-3 drops of black seed oil (Barij Essence Pharmaceutical Company, Kashan, Iran) on the lower abdomen twice daily for 8 weeks modestly improves symptoms of mixed urinary incontinence, as well as related quality of life, when compared to placebo. However, there was no beneficial effect of topical black seed oil on stress incontinence, urge incontinence, or severity of symptoms (110262).
• Vaginal candidiasis. Although there is interest in using intravaginal black seed for vaginal fungal infections, there is insufficient reliable information about the clinical effects of black seed for this condition.
• Vitiligo. It is unclear if topical black seed oil is beneficial for patients with vitiligo. Details: Preliminary clinical research in adults with vitiligo shows that applying a cream containing black seed oil to the skin twice daily for 6 months improves skin pigmentation. This cream induced repigmentation of 50% or more in around 44% of patients with facial or hand involvement and 88% of patients with genital region involvement (102064). The validity of these findings is limited by the lack of a comparator group. More evidence is needed to rate black seed for these uses.

(Read more about BLACK SEED)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral perilla is beneficial in patients with age-related cognitive decline. Details: Preliminary clinical research in healthy elderly adults shows that taking perilla seed oil 7 mL orally daily for 12 months does not improve cognitive function scores when compared with placebo. However, the study may have been inadequately powered to detect a difference between groups (110612). Other preliminary clinical research in healthy adults at least 60 years of age shows that taking perilla seed oil 1.47 mL orally daily for 12 months does not improve cognitive function scores when compared with baseline. However, taking perilla seed oil 1.47 mL plus ponkan powder 1.12 grams modestly improved cognitive function scores (110615).
• Allergic rhinitis (hay fever). It is unclear if oral perilla is beneficial in patients with allergic rhinitis. Details: Preliminary clinical research in patients with seasonal allergic rhinoconjunctivitis shows that taking perilla extract 50 or 200 mg orally daily for 21 days decreases symptoms such as itchy nose, watery eyes, itchy eyes, and total symptoms when compared with placebo (68658).
• Asthma. It is unclear if oral perilla is beneficial in patients with asthma. Details: Two very small clinical studies in adults with mild asthma show that taking perilla seed oil 10-20 grams orally daily for 4 weeks modestly improves peak expiratory flow, forced vital capacity, and forced expiratory volume in 1 second when compared with baseline and placebo (1338,65485).
• Cancer. Although there has been interest in using oral perilla for cancer, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Canker sores. It is unclear if oral perilla is beneficial in patients with canker sores. Details: Preliminary clinical research in patients with recurrent canker sores shows that using perilla seed oil as the only type of cooking oil for 8 months does not decreases the incidence of canker sores any better than using soybean oil (68676).
• Common cold. Although there has been interest in using oral perilla for the common cold, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Constipation. It is unclear if oral perilla is beneficial in patients with constipation. Details: Preliminary clinical research shows that taking a specific perilla leaf extract (Benegut, Vital Solutions GmbH) 150 mg orally twice daily for 4 weeks does not improve bloating, abdominal discomfort, gas, feelings of fullness, or stool frequency when compared with placebo in healthy adults who complain of gastrointestinal discomfort and reduced bowel movements (94312).
• Cough. Although there has been interest in using oral perilla for cough, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Dementia. It is unclear if oral perilla is beneficial in patients with dementia. Details: Preliminary clinical research in patients with mild to moderate dementia shows that taking perilla seed oil 1 gram orally three times daily for 6 months does not improve cognitive function when compared with placebo (101808).
• Depression. Although there has been interest in using oral perilla for depression, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Headache. Although there has been interest in using oral perilla for headache, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Nausea and vomiting. Although there has been interest in using oral perilla for nausea and vomiting, there is insufficient reliable information about the clinical effects of perilla for this purpose.
• Osteoporosis. Although there has been interest in using oral perilla for osteoporosis, there is insufficient reliable information about the clinical effects of perilla for this purpose. More evidence is needed to rate perilla for these uses.

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POSSIBLY EFFECTIVE

• Diabetes. Oral stinging nettle seems to improve glycemic control in patients with diabetes. Details: A meta-analysis of 8 small heterogeneous clinical trials in adults with type 2 diabetes shows that taking stinging nettle 1.5-10 grams in divided doses daily for 8-12 weeks reduces fasting blood glucose (FBG) by 18 mg/dL when compared with placebo (102865). Glycated hemoglobin (HbA1c) was not improved, but the study durations were not adequate to detect an improvement in this measure. Despite positive results on FBG, taking stinging nettle does not seem to improve insulin secretion or measures of insulin sensitivity (91519,102865,108903). Another meta-analysis of 3 small clinical studies in adults with type 2 diabetes shows that taking stinging nettle reduces HbA1c by about 1.3% when compared with placebo. This analysis also suggests stinging nettle reduces post-prandial blood glucose by about 114 mg/dL; however, this is based on a single study. Stinging nettle did not improve fasting blood glucose or insulin resistance in this analysis (111503). The validity of these findings is limited by the low quality and heterogeneity of included studies, as well as unclear dosing. Furthermore, since most research has been conducted in Iran, it is unknown if these findings are generalizable to other geographic locations. Stinging nettle has also been used in combination with other natural medicines. One small clinical study in adults with type 2 diabetes shows that taking a product containing stinging nettle leaf extract 200 mg, milk thistle 200 mg, and Boswellia serrata gum 200 mg three times daily for 3 months reduces FBP by about 28 mg/dL and HbA1c by about 1.5%, compared with a smaller reduction in the placebo group (96742). It is unclear if this effect is due to stinging nettle, the other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). It is unclear if oral stinging nettle is beneficial for hay fever. Details: Taking stinging nettle leaf extract 300 mg 3-7 times daily at the first sign of hay fever symptoms seems to provide subjective improvement (7035). However, adding stinging nettle to conventional allergy medication might not provide any additional benefit. One small clinical study shows that adding stinging nettle tablets (Urtidin, Barij Essence Pharmaceutical Co.) 150 mg four times daily for 1 month to treatment with loratadine and nasal saline rinses does not improve symptoms of allergic rhinitis when compared with placebo with loratadine and nasal saline rinses (96743).
• Anemia. Although there is interest in using oral stinging nettle for anemia, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Asthma. Although there is interest in using oral stinging nettle for asthma, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Benign prostatic hyperplasia (BPH). It is unclear if oral stinging nettle is beneficial for BPH. Details: A meta-analysis of clinical research, including 5 clinical studies and 1,128 patients with BPH, shows that taking stinging nettle root extract 360-600 mg in divided doses daily for 2-12 months improves peak urinary flow rate and symptom scores while modestly reducing prostate volume when compared with control. However, the validity of these results is limited by significant heterogeneity due to the variability in the products used and the specific endpoints investigated (96744). In the largest clinical trial in the analysis, patients took stinging nettle root extract 120 mg three times daily for 6 months (76406). Stinging nettle has also been evaluated in combination products. Clinical research in patients with BPH shows that taking a specific combination product (PRO 160/120, Dr. Willmar Schwabe Pharmaceuticals) containing a specific extract of stinging nettle root (WS 1031) 120 mg plus a specific extract of saw palmetto fruit (WS 1473) 160 mg twice daily for 24-48 weeks seems to improve urinary tract symptoms when compared with control; the effect may last at least 48 weeks after treatment (15195,15551,76409). However, taking a different combination product does not seem to be beneficial. A small clinical study in patients with BPH shows that taking a product containing stinging nettle root extract 240 mg, saw palmetto, pumpkin seed oil, lemon bioflavonoid, and beta-carotene, three times daily for 6 months, does not improve symptoms of BPH (5093).
• Bleeding. Topical stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Some preliminary clinical research shows that applying 4 mL of a specific product (Ankaferd blood stopper, Mefar Ilaç Sanayi A.S) containing alpinia, licorice, thyme, stinging nettle, and common grape vine to the affected area reduces bleeding, but does not improve the time for episiotomy repair, when compared with using saline (31010).
• Gingivitis. Stinging nettle in a mouthwash solution has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with moderate gingival inflammation suggests that using 10 mL of mouthwash solution containing a 1:1:1 mixture of stinging nettle, juniper, and yarrow twice daily for 3 months does not reduce plaque or bleeding when compared with control (76443). It is not clear if this effect is due to stinging nettle, the other ingredients, or the combination.
• Gout. Although there is interest in using oral stinging nettle for gout, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Gulf war syndrome. It is unclear if oral stinging nettle is beneficial for Gulf war syndrome. Details: A very small exploratory clinical trial in males with Gulf war syndrome shows that taking stinging nettle leaf (Nature's Way) 1305 mg in two divided doses daily for 30 days modestly improves symptom severity when compared with placebo (108311). The clinical relevance of this finding is limited by the use of an unvalidated scoring scale. Additionally, it appears that most patients had mild, unspecified symptoms at baseline; it is unclear if stinging nettle is beneficial for moderate to severe symptoms.
• Hyperandrogenism. It is unclear if oral stinging nettle is beneficial in patients with hyperandrogenism. Details: Preliminary clinical research in females with hyperandrogenism shows that taking dried extract of stinging nettle root 300-600 mg daily for approximately 4 months decreases total and free testosterone levels, but not menstrual cycle conditions, oily skin, or acne, when compared with taking spironolactone and cyproterone (91520).
• Insect bite. Oral stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that applying a homeopathic after-bite gel, containing stinging nettle, Echinacea, and marsh Labrador tea, on affected areas does not reduce erythema or itching after a mosquito bite when compared with placebo (89235).
• Kidney stones (nephrolithiasis). Although there is interest in using oral stinging nettle for kidney stones, there is insufficient reliable information about the clinical effects of stinging nettle for this condition.
• Myalgia. Although there is interest in using topical stinging nettle for myalgia, there is insufficient reliable information about the clinical effects of stinging nettle for this purpose.
• Osteoarthritis. Small clinical studies suggest that topical stinging nettle may modestly improve pain in patients with osteoarthritis. It is unclear if oral stinging nettle is beneficial. Details: Topically, stinging nettle leaf may have a counterirritant effect which may improve osteoarthritis pain in some patients. A small clinical study in patients ages 45-82 with osteoarthritis of the thumb shows that applying raw stinging nettle leaf to the thumb for 30 seconds daily for 1 week reduces pain and disability when compared with white dead nettle leaf control (12490). However, in another small clinical study in patients with knee osteoarthritis, topical application of raw stinging nettle leaf to the knee for 1 minute daily for 7 days does not seem to be more effective for reducing pain than applying a leaf from a related stingless nettle (76412). Non-raw stinging nettle has also been tried. In a small open-label study, a formulation of stinging nettle extract (Liquid PhytoCaps Nettle Leaf, Gaia Herbs) 13.33% compounded with lipobase oil-in-water emulsion and applied to the affected area twice daily for 2 weeks, modestly improves pain and function in patients with radiologically confirmed osteoarthritis when compared with baseline (76414). The validity of this finding is limited by the lack of a comparator group. Stinging nettle has also been evaluated orally, in combination with other ingredients. A clinical study in adults with knee osteoarthritis shows that taking a specific combination solution (Rosaxan, medAgil Gesundheitsgesellschaft mbH) containing stinging nettle extract 160 mg, rose hip puree 20 grams, devil's claw 108 mg, and vitamin D 200 IU daily for 12 weeks improves symptoms by an additional 28% and pain scores by an additional 33% when compared with placebo (96741). It is unclear if this effect is due to stinging nettle, the other ingredients, or the combination.
• Tinnitus. Oral stinging nettle has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with tinnitus shows that taking a specific product containing stinging nettle, tansy, and rose hip (Neurotec, Rose Pharmed), 100 mg orally daily for 3 months does not improve auditory thresholds when compared with placebo. However, the product improved some subjective symptoms scores, such as perceived loudness and severity scores (110512).
• Urinary tract infections (UTIs). Although there is interest in using oral stinging nettle for UTIs, there is insufficient reliable information about the clinical effects of stinging nettle for this condition. More evidence is needed to rate stinging nettle for these uses.

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LIKELY SAFE ...when used orally in amounts found in foods (6).

POSSIBLY SAFE ...when black seed oil is used orally at doses of up to 5 mL or 5 grams daily for up to 12 weeks (36071,94486,96927,96929,98815,101550,102062,110269,110276). ...when a specific black seed oil formulation containing 5% thymoquinone (BlaQmax) is used in doses of 200 mg daily for 90 days (110264). ...when black seed powder is used orally at doses of up to 2 grams daily for up to 12 months (36239,36244,94478,94479,94485,96928,102061,110268,110271). ...when used topically and appropriately, short-term. There is some clinical evidence that black seed oil can be safely applied as an oil 2 times daily for up to 6 months or 3 times daily for up to 1 month (95981,98814,102064,110262) or as a 30% gel twice daily for approximately 2 months (94483).

CHILDREN: POSSIBLY SAFE
when black seed oil is used orally at doses of 40-80 mg/kg daily for 2-19 months in children ages 4-17 years old (36071,95984). However, the higher dose of 80 mg/kg daily has been associated with increased adverse effects such as gastrointestinal complaints when taken on an empty stomach (36071).

PREGNANCY: LIKELY UNSAFE
when used orally in amounts exceeding those found in food. Black seed may decrease or inhibit uterine contractions (241) and may have contraceptive activity (242).

LACTATION:
Insufficient reliable information available; avoid using.

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POSSIBLY SAFE ...when perilla oil or extract is used orally and appropriately. There is some evidence that perilla can be safely used for up to 12 months (1338,68676,94312,105525).

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

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POSSIBLY SAFE ...when used orally and appropriately. Stinging nettle root 360-600 mg has been used safely for up to 1 year (5093,11230,15195,76406,96744). ...when used topically and appropriately (12490).

PREGNANCY: LIKELY UNSAFE
when used orally due to possible abortifacient and uterine-stimulant effects (4,6,19).

LACTATION:
Insufficient reliable information available; avoid using.

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ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro and animal research suggests that black seed extract can inhibit platelet aggregation and clotting, and increase bleeding time (36029,36049,36100,108701). In addition, decreased platelet counts have occurred in a human case report and in animal research (104665).

ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking black seed with antidiabetes drugs might increase the risk of hypoglycemia.  Details Some clinical research (36262,94479,94485,101552,102062,110269,110276) and numerous animal studies (36037,36086,36150,36155,36214,110270) suggest that black seed, especially its constituent thymoquinone, can have hypoglycemic effects.

ANTIHYPERTENSIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, taking black seed with antihypertensive drugs might increase the risk of hypotension.  Details Clinical research suggests that black seed powder and oil might reduce blood pressure by 2-3 mmHg (16437,94489). In animal research, black seed modestly reduces blood pressure and concomitant use of black seed and amlodipine (Norvasc) or metoprolol (Lopressor) increased the blood pressure lowering effects of these drugs (101559,108703).

CLOPIDOGREL (Plavix) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed may increase the risk of bleeding if used with clopidogrel.  Details Animal research shows that taking black seed extract daily for 2 weeks prior to a single dose of clopidogrel increases maximum concentrations of clopidogrel by approximately 31% and modestly decreases oral clearance. Furthermore, bleeding time was increased by 12% (108701). This has not been shown in humans.

CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use with drugs that have sedative properties may cause additive effects.  Details Animal research suggests that black seed may have CNS depressant effects (36064).

CYCLOSPORINE (Neoral, Sandimmune) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically taking black seed might reduce the levels and clinical effects of cyclosporine.  Details In animal research, black seed extract decreased the maximal levels of cyclosporine in the blood by 35.5% (94474). This has not been shown in humans.

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase levels of drugs metabolized by CYP2C9.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of phenytoin by a mechanism possibly related to the inhibition of CYP2C9 (110281). The effect of black seed on CYP2C9 is unclear. This has not been shown in humans.

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking black seed with diuretic drugs might increase potassium loss and the risk of hypokalemia.  Details Black seed extract has shown diuretic effects in animals, which could theoretically increase potassium loss (36026). This has not been shown in humans.

IMMUNOSUPPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might interfere with immunosuppressive therapy.  Details Animal and in vitro studies suggest that black seed might stimulate immune function (36086,36137,36161). However, other animal studies suggest that black seed may suppress immune function (36085,36142).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase levels and adverse effects of phenytoin.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of phenytoin (110281). This effect may be due to inhibition of cytochrome P450 2C9 (CYP2C9). The effect of black seed on phenytoin metabolism is unclear. This has not been shown in humans.

SEROTONERGIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining serotonergic drugs with black seed might increase the risk of serotonergic side effects, including serotonin syndrome and cerebral vasoconstrictive disorders.  Details Animal research suggests that black seed can increase brain serotonin levels (36180,94488). In one case report, a 35-year-old man undergoing endoscopic surgery experienced immediate postoperative serotonin syndrome that was likely associated with the use of black seed oil 600 mg daily starting 4 days before surgery, and precipitated by the use of serotonergic pain medications, including fentanyl and oxycodone (101558). Monitor patients for signs of serotonin syndrome and other serotonergic side effects if using black seed with serotonergic drugs.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, black seed might increase levels of warfarin and increase the risk of bleeding.  Details In vitro research suggests that thymoquinone, a constituent of black seed, can decrease the metabolism of warfarin (110280). This effect may be due to inhibition of cytochrome P450 2C9 (CYP2C9). The effect of black seed on warfarin metabolism is unclear. This has not been shown in humans.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, stinging nettle might have additive effects with antidiabetes drugs.  Details Clinical research shows that stinging nettle might decrease blood glucose levels in patients with diabetes (91519,102865).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, combining stinging nettle with diuretic drugs may have additive effects.  Details Animal research suggests that the above ground parts and roots of stinging nettle may have a diuretic effect (1,4,11,76402).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, stinging nettle might reduce excretion and increase levels of lithium.  Details Animal research suggests that stinging nettle has diuretic and natriuretic properties, which could alter the excretion of lithium (76402). The dose of lithium might need to be decreased.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D There is some concern that stinging nettle might decrease the effects of anticoagulant drugs such as warfarin.  Details Stinging nettle contains a significant amount of vitamin K (19). When taken in large quantities, this might interfere with the activity of warfarin.

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General ...Orally and topically, black seed seems to be well tolerated.
Most Common Adverse Effects:
Orally: Constipation, gastric burning or discomfort, nausea, and vomiting.

Dermatologic ...Orally, black seed can cause itching, but this adverse effect is rare (94481). It has also been reported to cause bullous drug eruption and maculopapular eruption (94480,100324). Topically, black seed and its oil have been reported to cause allergic contact dermatitis (36053,36296,36297,100324). Rarely, topical use of the oil has been reported to cause a rash related to drug reaction with eosinophilia and systemic symptoms (DRESS) (110277).

Gastrointestinal ...In a clinical trial, unspecified gastrointestinal complaints occurred in 20% of patients taking black seed oil orally (36071). Gastrointestinal complaints occurred rarely in another clinical trial; however, one patient in this study was hospitalized for nausea and vomiting thought to be associated with black seed oil (110267). Gastrointestinal adverse effects to black seed have included constipation (36180), burning sensation (94487), epigastric discomfort (94479), vomiting (94491), or mild nausea (94481,94489,94491,96927,96929). Gastrointestinal adverse effects to a specific black seed oil formulation containing 5% thymoquinone (BlaQmax) have included mild cases of bloating, burping and mild diarrhea (110264).

Genitourinary ...Orally, relatively severe menstrual bleeding has occurred in one clinical trial (104661).

Hepatic ...While intake of black seed has been associated with hepatotoxicity in some animal research, other animal research has not confirmed this finding (245,95982). Hepatotoxicity has not been reported in humans.

Immunologic ...Orally, black seed has been reported to cause bullous drug eruption and maculopapular eruption (94480,100324). Topically, black seed and its oil can cause allergic contact dermatitis (6,36053,36296,36297,100324,110266). One case of bullous drug eruption with skin detachment has been reported for a 54-year-old woman who used black seed oil orally. The eruptions resolved following treatment with clobetasol propionate 0.05%. Although this patient showed a positive skin prick test for undiluted black seed oil, the tests were negative when the oil was diluted to 10% and 1% (94480). A 28-year-old woman developed a rash following topical use of black seed oil. She was diagnosed with drug reaction with eosinophilia and systemic symptoms (DRESS), including enlarged lymph nodes, and required systemic corticosteroid treatment. This diagnosis was confirmed six months later following confirmation with a patch test (110277). In another case report, a 58-year-old woman developed eczematous lesions on the lower and upper eyelids after topical application of an oil containing black seed. This reaction was followed by the development of a diffuse maculopapular eruption after taking two oral capsules containing black seed oil. It is theorized that the topical application of black seed oil led to systemic sensitization prior to the use of oral black seed in this patient (100324).

Renal ...Orally, black seed might cause renal dysfunction. A case of acute renal failure thought to be related to use of black seed tablets 2-2.5 grams daily has been reported for a 62 year-old patient with diabetes (94477).

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General ...Orally, perilla seems to be well tolerated. Topically, there is currently a limited amount of information on the adverse effects of perilla.
Most Common Adverse Effects:
Topically: Dermatitis.
Serious Adverse Effects (Rare):
Orally: Anaphylaxis.

Dermatologic ...Topically, perilla may cause contact dermatitis (6,68664,94313).

Immunologic ...Orally, many cases of anaphylaxis have been reported in adults and children who consumed perilla seeds (94313,110611). Some research suggests that oleosin is the major constituent responsible for perilla allergies (110611).

Pulmonary/Respiratory ...Occupational asthma has been reported from breathing in smoke from roasted perilla seeds (94313).

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General ...Orally, stinging nettle seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Constipation, diarrhea.
Topically: Contact with the raw plant causes itching, rash, and stinging.

Dermatologic ...Topically, fresh stinging nettle leaves and stalk can cause localized rash, itching, and stinging (12490,76399,76412,76414,76417,76428,76448,96746). Usually, short exposure to stinging nettle results in a transient urticarial reaction and a stinging sensation which may persist for more than 12 hours (76399,76414,76417,96746). In one report, a patient placed a fresh stinging nettle leaf on the tongue to suck out the sap of the leaf. Severe tongue edema, pain, and urticaria developed within 5 minutes. Symptoms continued for several hours after the leaf was removed (15197). In another case report, a young couple intoxicated with methamphetamine fell and laid in a stinging nettle bush for 20 minutes, after which urticaria and pain continued for 2-3 weeks, and a heightened sensitivity to cold persisted for several months (96746).

Endocrine ...A case of gynecomastia has been reported for a 33-year-old male who consumed stinging nettle tea 2 cups daily for one month prior to symptom onset. The condition subsided one month after discontinuing stinging nettle tea (76410).
There have been two cases of galactorrhea associated with the consumption of stinging nettle for one month (76410,108902). In one case, a 33-year-old female consuming stinging nettle tea showed high levels of estradiol and low levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). The levels of these hormones normalized 6 weeks after discontinuing stinging nettle tea (76410). In the other case report describing a 30-year-old female self-treating with stinging nettle 500 mg daily, hormone levels were not reported; however, a mammogram showed scattered areas of fibroglandular density and benign-appearing calcifications. This patient had complete resolution of symptoms 1 week after discontinuation of stinging nettle (108902).

Gastrointestinal ...Orally, stinging nettle root can cause gastrointestinal complaints, including diarrhea and constipation (1,7,11230). Stinging nettle above ground parts may cause mild gastrointestinal discomfort when taken on an empty stomach (7035). Stinging nettle juice may cause diarrhea (1). One patient taking a combination product containing stinging nettle root extract and pygeum bark extract (Prostatonin, Pharmaton) experienced continual gastrointestinal pain and hyperperistalsis. It is not clear if this effect was due to stinging nettle or pygeum (70230).

Genitourinary ...There is a case report of decreased ejaculatory volume associated with an herbal blend product containing stinging nettle root extract, saw palmetto extract, pumpkin seed oil extract, lemon bioflavonoid extract, and beta-carotene (5093). It is unclear if this was due to stinging nettle, other ingredients, or the combination.

Hepatic ...A case of idiosyncratic drug-induced liver disease (DILI) is reported in a 36-year-old female who presented with abdominal pain after 1 month of taking an herbal liver detox tea containing stinging nettle and other ingredients. Remarkable laboratory values included elevated liver enzymes, alkaline phosphatase, and total bilirubin. The patient received a loading dose of N-acetylcysteine and was hospitalized for 12 days (112178). However, it is unclear if the adverse effect was due to the stinging nettle, other ingredients, or the combination.

Other ...Orally, stinging nettle root can cause sweating (1,7).

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