Filtered Water • Sucarose • Acai Extract • Panax ginseng root • Caramel Extract • Color C • Citric Acid • Sodiumbenzoate • Ascorbic Acid .
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Below is general information about the effectiveness of the known ingredients contained in the product Guaraviton. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
INSUFFICIENT RELIABLE EVIDENCE to RATE
Alpha hydroxy acids represent a group of natural chemicals that are used alone or in combination. See specific monographs for effectiveness information.
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
Below is general information about the safety of the known ingredients contained in the product Guaraviton. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
POSSIBLY SAFE ...when used orally and appropriately, short-term. Acai pulp, in a dose of up to 162.5 grams daily, has been used with apparent safety for up to 3 months in clinical research (17731,99400). There is insufficient reliable information available about the safety of acai when used topically.
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
Some alpha hydroxy acids are used topically, while others are used orally, intravaginally, or by inhalation. See specific monographs for safety information.
PREGNANCY AND LACTATION:
See specific monographs for safety information.
LIKELY SAFE ...when used orally and appropriately, short-term. Panax ginseng seems to be safe when used for up to 6 months (8813,8814,17736,89741,89743,89745,89746,89747,89748,103044,103477).
POSSIBLY UNSAFE ...when used orally, long-term. There is some concern about the long-term safety due to potential hormone-like effects, which might cause adverse effects with prolonged use (12537). Tell patients to limit continuous use to less than 6 months. There is insufficient reliable information available about the safety of Panax ginseng when used topically.
CHILDREN: LIKELY UNSAFE
when used orally in infants.
Use of Panax ginseng in newborns is associated with intoxication that can lead to death (12). There is limited reliable information available about use in older children (24109,103049); avoid using.
PREGNANCY: POSSIBLY UNSAFE
when used orally.
Ginsenoside Rb1, an active constituent of Panax ginseng, has teratogenic effects in animal models (10447,24106,24107); avoid using.
LACTATION:
Insufficient reliable information available; avoid using.
LIKELY SAFE ...when used orally, topically, intramuscularly, or intravenously and appropriately. Vitamin C is safe when taken orally in doses below the tolerable upper intake level (UL). Tell patients not to exceed the UL of 2000 mg daily (1959,4713,4714,4844). ...when used intravenously or intramuscularly and appropriately. Injectable vitamin C is an FDA-approved prescription product (15).
POSSIBLY UNSAFE ...when used orally in excessive doses. Doses greater than the tolerable upper intake level (UL) of 2000 mg daily can significantly increase the risk of adverse effects such as osmotic diarrhea and gastrointestinal upset (4844).
CHILDREN: LIKELY SAFE
when used orally and appropriately (4844,10352,14443).
CHILDREN: POSSIBLY UNSAFE
when used orally in excessive amounts.
Tell patients not to use doses above the tolerable upper intake level (UL) of 400 mg daily for children ages 1 to 3 years, 650 mg daily for children 4 to 8 years, 1200 mg daily for children 9 to 13 years, and 1800 mg daily for adolescents 14 to 18 years. Higher doses can cause osmotic diarrhea and gastrointestinal upset (4844).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (4844).
PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses.
Tell patients over age 19 not to use doses exceeding the UL of 2000 mg daily when pregnant or breast-feeding and for those 14-18 years of age not to use doses exceeding 1800 mg daily when pregnant or breast-feeding. Higher doses can cause osmotic diarrhea and gastrointestinal upset. Large doses of vitamin C during pregnancy can also cause newborn scurvy (4844); avoid using.
Below is general information about the interactions of the known ingredients contained in the product Guaraviton. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
Theoretically, taking acai with antidiabetes drugs might interfere with glycemic control.
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Although Panax ginseng has shown antiplatelet effects in the laboratory, it is unlikely to increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
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In vitro evidence suggests that ginsenoside constituents in Panax ginseng might decrease platelet aggregation (1522,11891). However, research in humans suggests that ginseng does not affect platelet aggregation (11890). Animal research indicates low oral bioavailability of Rb1 and rapid elimination of Rg1, which might explain the discrepancy between in vitro and human research (11153). Until more is known, use with caution in patients concurrently taking anticoagulant or antiplatelet drugs.
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Theoretically, taking Panax ginseng with antidiabetes drugs might increase the risk of hypoglycemia.
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Clinical research suggests that Panax ginseng might decrease blood glucose levels (89740). Monitor blood glucose levels closely.
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Theoretically, taking Panax ginseng with caffeine might increase the risk of adverse stimulant effects.
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Theoretically, Panax ginseng might decrease levels of drugs metabolized by CYP1A1.
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In vitro research shows that Panax ginseng can induce the CYP1A1 enzyme (24104).
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Theoretically, Panax ginseng might increase levels of drugs metabolized by CYP2D6. However, research is conflicting.
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There is some evidence that Panax ginseng can inhibit the CYP2D6 enzyme by approximately 6% (1303,51331). In addition, in animal research, Panax ginseng inhibits the metabolism of dextromethorphan, a drug metabolized by CYP2D6, by a small amount (103478). However, contradictory research suggests Panax ginseng might not inhibit CYP2D6 (10847). Until more is known, use Panax ginseng cautiously in patients taking drugs metabolized by these enzymes.
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Theoretically, Panax ginseng might increase or decrease levels of drugs metabolized by CYP3A4.
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Panax ginseng may affect the clearance of drugs metabolized by CYP3A4. One such drug is imatinib. Inhibition of CYP3A4 was believed to be responsible for a case of imatinib-induced hepatotoxicity (89764). In contrast, Panax ginseng has been shown to increase the clearance of midazolam, another drug metabolized by CYP3A4 (89734,103478). Clinical research shows that Panax ginseng can reduce midazolam area under the curve by 44%, maximum plasma concentration by 26%, and time to reach maximum plasma concentration by 29% (89734). Midazolam metabolism was also increased in animals given Panax ginseng (103478). Until more is known, use Panax ginseng cautiously in combination with CYP3A4 substrates.
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Theoretically, concomitant use of large amounts of Panax ginseng might interfere with hormone replacement therapy.
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Theoretically, Panax ginseng might decrease blood levels of oral or intravenous fexofenadine.
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Animal research suggests that taking Panax ginseng in combination with oral or intravenous fexofenadine may reduce the bioavailability of fexofenadine. Some scientists have attributed this effect to the ability of Panax ginseng to increase the expression of P-glycoprotein (24101).
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Theoretically, Panax ginseng might reduce the effects of furosemide.
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There is some concern that Panax ginseng might contribute to furosemide resistance. There is one case of resistance to furosemide diuresis in a patient taking a germanium-containing ginseng product (770).
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Theoretically, Panax ginseng might increase the effects and adverse effects of imatinib.
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A case of imatinib-induced hepatotoxicity has been reported for a 26-year-old male with chronic myelogenous leukemia stabilized on imatinib for 7 years. The patient took imatinib 400 mg along with a Panax ginseng-containing energy drink daily for 3 months. Since imatinib-associated hepatotoxicity typically occurs within 2 years of initiating therapy, it is believed that Panax ginseng affected imatinib toxicity though inhibition of cytochrome P450 3A4. CYP3A4 is the primary enzyme involved in imatinib metabolism (89764).
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Theoretically, Panax ginseng use might interfere with immunosuppressive therapy.
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Panax ginseng might have immune system stimulating properties (3122).
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Theoretically, taking Panax ginseng with insulin might increase the risk of hypoglycemia.
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Clinical research suggests that Panax ginseng might decrease blood glucose levels (89740). Insulin dose adjustments might be necessary in patients taking Panax ginseng; use with caution.
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Although Panax ginseng has demonstrated variable effects on cytochrome P450 3A4 (CYP3A4), which metabolizes lopinavir, Panax ginseng is unlikely to alter levels of lopinavir/ritonavir.
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Lopinavir is metabolized by CYP3A4 and is administered with the CYP3A4 inhibitor ritonavir to increase its plasma concentrations. Panax ginseng has shown variable effects on CYP3A4 activity in humans (89734,89764). However, taking Panax ginseng (Vitamer Laboratories) 500 mg twice daily for 14 days did not alter the pharmacokinetics of lopinavir/ritonavir in 12 healthy volunteers (93578).
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Theoretically, Panax ginseng may increase the clearance of midazolam.
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Midazolam is metabolized by cytochrome P450 3A4 (CYP3A4). Clinical research suggests that Panax ginseng can reduce midazolam area under the curve by 44%, maximum plasma concentration by 26%, and time to reach maximum plasma concentration by 29% (89734). Midazolam metabolism was also increased in animals given Panax ginseng (103478).
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Theoretically, Panax ginseng can interfere with MAOI therapy.
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Theoretically, taking Panax ginseng with nifedipine might increase serum levels of nifedipine and the risk of hypotension.
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Preliminary clinical research shows that concomitant use can increase serum levels of nifedipine in healthy volunteers (22423). This might cause the blood pressure lowering effects of nifedipine to be increased when taken concomitantly with Panax ginseng.
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Theoretically, Panax ginseng has an additive effect with drugs that prolong the QT interval and potentially increase the risk of ventricular arrhythmias. However, research is conflicting.
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Theoretically, taking Panax ginseng with raltegravir might increase the risk of liver toxicity.
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A case report suggests that concomitant use of Panax ginseng with raltegravir can increase serum levels of raltegravir, resulting in elevated liver enzymes levels (23621).
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Theoretically, Panax ginseng might increase or decrease levels of selegiline, possibly altering the effects and side effects of selegiline.
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Animal research shows that taking selegiline with a low dose of Panax ginseng extract (1 gram/kg) reduces selegiline bioavailability, while taking a high dose of Panax ginseng extract (3 grams/kg) increases selegiline bioavailability (103053). More research is needed to confirm these effects.
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Theoretically, taking Panax ginseng with stimulant drugs might increase the risk of adverse stimulant effects.
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Panax ginseng might affect the clearance of warfarin. However, this interaction appears to be unlikely.
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There has been a single case report of decreased effectiveness of warfarin in a patient who also took Panax ginseng (619). However, it is questionable whether Panax ginseng was the cause of this decrease in warfarin effectiveness. Some research in humans and animals suggests that Panax ginseng does not affect the pharmacokinetics of warfarin (2531,11890,17204,24105). However, other research in humans suggests that Panax ginseng might modestly increase the clearance of the S-warfarin isomer (15176). More evidence is needed to determine whether Panax ginseng causes a significant interaction with warfarin.
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High-dose vitamin C might slightly prolong the clearance of acetaminophen.
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A small pharmacokinetic study in healthy volunteers shows that taking high-dose vitamin C (3 grams) 1.5 hours after taking acetaminophen 1 gram slightly increases the apparent half-life of acetaminophen from around 2.3 hours to 3.1 hours. Ascorbic acid competitively inhibits sulfate conjugation of acetaminophen. However, to compensate, elimination of acetaminophen glucuronide and unconjugated acetaminophen increases (6451). This effect is not likely to be clinically significant.
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Theoretically, antioxidant effects of vitamin C might reduce the effectiveness of alkylating agents.
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The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs that generate free radicals, such as cyclophosphamide, chlorambucil, carmustine, busulfan, and thiotepa (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effect, if any, antioxidants such as vitamin C have on chemotherapy.
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Vitamin C can increase the amount of aluminum absorbed from aluminum compounds.
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Research in animals and humans shows that vitamin C increases aluminum absorption, theoretically by chelating aluminum and keeping it in solution where it is available for absorption (10549,10550,10551,21556). In people with normal renal function, urinary excretion of aluminum will likely increase, making aluminum retention and toxicity unlikely (10549). Patients with renal failure who take aluminum-containing compounds such as phosphate binders should avoid vitamin C supplements in doses above the recommended dietary allowances.
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Theoretically, the antioxidant effects of vitamin C might reduce the effectiveness of antitumor antibiotics.
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The use of antioxidants like vitamin C during chemotherapy is controversial. There is concern that antioxidants could reduce the activity of chemotherapy drugs which generate free radicals, such as doxorubicin (391). In contrast, some researchers theorize that antioxidants might make chemotherapy more effective by reducing oxidative stress that could interfere with apoptosis (cell death) of cancer cells (14012,14013). More evidence is needed to determine what effects, if any, antioxidants such as vitamin C have on chemotherapy.
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Acidification of the urine by vitamin C might increase aspirin levels.
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It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction is not clinically significant.
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Acidification of the urine by vitamin C might increase choline magnesium trisalicylate levels.
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It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046,4531). However, short-term use of up to 6 grams daily of vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.
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Vitamin C might increase blood levels of estrogens.
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Increases in plasma estrogen levels of up to 55% occur under some circumstances when vitamin C is taken concurrently with oral contraceptives or hormone replacement therapy, including topical products (129,130,11161). It is suggested that vitamin C prevents oxidation of estrogen in the tissues, regenerates oxidized estrogen, and reduces sulfate conjugation of estrogen in the gut wall (129,11161). When tissue levels of vitamin C are high, these processes are already maximized and supplemental vitamin C does not have any effect on estrogen levels. Increases in plasma estrogen levels may occur when patients who are deficient in vitamin C take supplements (11161). Monitor these patients for estrogen-related side effects.
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Theoretically, vitamin C might decrease levels of fluphenazine.
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In one patient there was a clinically significant decrease in fluphenazine levels when vitamin C (500 mg twice daily) was started (11017). The mechanism is not known, and there is no further data to confirm this interaction.
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Vitamin C can modestly reduce indinavir levels.
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One pharmacokinetic study shows that taking vitamin C 1 gram orally once daily along with indinavir 800 mg orally three times daily reduces the area under the concentration-time curve of indinavir by 14%. The mechanism of this interaction is unknown, but it is unlikely to be clinically significant in most patients. The effect of higher doses of vitamin C on indinavir levels is unknown (11300,93578).
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Vitamin C can increase levothyroxine absorption.
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Two clinical studies in adults with poorly controlled hypothyroidism show that swallowing levothyroxine with a glass of water containing vitamin C 500-1000 mg in solution reduces thyroid stimulating hormone (TSH) levels and increases thyroxine (T4) levels when compared with taking levothyroxine alone. This suggests that vitamin C increases the oral absorption of levothyroxine, possibly due to a reduction in pH (102978).
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Vitamin C might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.
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A combination of niacin and simvastatin (Zocor) effectively raises HDL cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (vitamin C, vitamin E, beta-carotene, and selenium) along with niacin and simvastatin (Zocor) attenuates this rise in HDL, specifically the HDL-2 and apolipoprotein A1 fractions, by more than 50% in patients with coronary disease (7388,11537). It is not known whether this adverse effect is due to a single antioxidant such as vitamin C, or to the combination. It also is not known whether it will occur in other patient populations.
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Acidification of the urine by vitamin C might increase salsalate levels.
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It has been suggested that acidification of the urine by vitamin C could increase reabsorption of salicylates by the renal tubules, and increase plasma salicylate levels (3046). However, short-term use of up to 6 grams/day vitamin C does not seem to affect urinary pH or salicylate excretion (10588,10589), suggesting this interaction probably is not clinically significant.
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High-dose vitamin C might reduce the levels and effectiveness of warfarin.
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Vitamin C in high doses may cause diarrhea and possibly reduce warfarin absorption (11566). There are reports of two people who took up to 16 grams daily of vitamin C and had a reduction in prothrombin time (9804,9806). Lower doses of 5-10 grams daily can also reduce warfarin absorption. In many cases, this does not seem to be clinically significant (9805,9806,11566,11567). However, a case of warfarin resistance has been reported for a patient who took vitamin C 500 mg twice daily. Cessation of vitamin C supplementation resulted in a rapid increase in international normalized ratio (INR) (90942). Tell patients taking warfarin to avoid taking vitamin C in excessively high doses (greater than 10 grams daily). Lower doses may be safe, but the anticoagulation activity of warfarin should be monitored. Patients who are stabilized on warfarin while taking vitamin C should avoid adjusting vitamin C dosage to prevent the possibility of warfarin resistance.
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Below is general information about the adverse effects of the known ingredients contained in the product Guaraviton. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
General ...Orally, acai seems to be well tolerated.
Other ...Raw acai fruit and juice can be contaminated with a parasitic protozoan called Trypanosoma cruzi, which causes American trypanosomiasis or Chagas Disease. A Brazilian outbreak of this disease in 2006 was linked to consumption of acai juice (17194,30245).
General ...Alpha hydroxy acids represent a group of natural chemicals, some of which can cause adverse effects. See specific monographs for safety information.
General
...Orally, Panax ginseng is generally well tolerated when used for up to 6 months.
There is some concern about the long-term safety due to potential hormone-like effects.
Topically, no adverse effects have been reported when ginseng is used as a single ingredient. However, a thorough evaluation of safety outcomes has not been conducted.
Most Common Adverse Effects:
Orally: Insomnia.
Serious Adverse Effects (Rare):
Orally: Anaphylaxis, arrhythmia, ischemia, Stevens-Johnson syndrome.
Cardiovascular ...Panax ginseng may cause hypertension, hypotension, and edema when used orally in high doses, long-term (3353). However, single doses of Panax ginseng up to 800 mg are not associated with changes in electrocardiogram (ECG) parameters or increases in heart rate or blood pressure (96218). There is a case report of menometrorrhagia and tachyarrhythmia in a 39-year-old female who took Panax ginseng 1000-1500 mg/day orally and also applied a facial cream topically that contained Panax ginseng. Upon evaluation for menometrorrhagia, the patient also reported a history of palpitations. It was discovered that she had sinus tachycardia on ECG. However, the patient was a habitual consumer of coffee 4-6 cups/day and at the time of evaluation was also mildly anemic. The patient was advised to discontinue taking Panax ginseng. During the 6 month period following discontinuation the patient did not have any more episodes of menometrorrhagia or tachyarrhythmia (13030). Also, a case of transient ischemic attack secondary to a hypertensive crisis has been reportedly related to oral use of Panax ginseng (89402).
Dermatologic
...Orally, Panax ginseng may cause itching or an allergic response consisting of systemic rash and pruritus (89743,89760,104953).
Skin eruptions have also been reported with use of Panax ginseng at high dosage, long-term (3353). Uncommon side effects with oral Panax ginseng include Stevens-Johnson syndrome (596).
In one case report, a 6-year-old male with a previous diagnosis of generalized pustular psoriasis, which had been in remission for 18 months, presented with recurrent pustular lesions after consuming an unspecified dose of Panax ginseng. The patient was diagnosed with pityriasis amiantacea caused by subcorneal pustular dermatosis. Treatment with oral dapsone 25 mg daily was initiated, and symptoms resolved after 4 weeks (107748).
Topically, when a specific multi-ingredient cream preparation (SS Cream) has been applied to the glans penis, mild pain, local irritation, and burning have occurred (2537).
Endocrine
...The estrogenic effects of ginseng are controversial.
Some clinical evidence suggests it doesn't have estrogen-mediated effects (10981). However, case reports of ginseng side effects such as postmenopausal vaginal bleeding suggest estrogenic activity (590,591,592,10982,10983).
In a 12-year-old Korean-Japanese male, enlargement of both breasts with tenderness in the right breast (gynecomastia) occurred after taking red ginseng extract 500 mg daily orally for one month. Following cessation of the product, there was no further growth or pain (89733). Swollen and tender breasts also occurred in a 70-year-old female using Panax ginseng orally (590).
Gastrointestinal ...Orally, Panax ginseng can cause decreased appetite (3353), diarrhea (3353,89734,103477), abdominal pain (89734,87984), and nausea (589,87984). However, these effects are typically associated with long-term, high-dose usage (3353).
Genitourinary
...Amenorrhea has been reported with oral use of Panax ginseng (3353).
Topically, when a specific multi-ingredient cream preparation (SS Cream) has been applied to the glans penis, sporadic erectile dysfunction and excessively delayed ejaculation have occurred (2537). Less commonly, patients can experience vaginal bleeding (591,592,3354,23630).
Hepatic ...Uncommon side effects can include cholestatic hepatitis (associated with a Panax ginseng-containing, multi-ingredient product, Prostata), such as that which occurred in a 65-year old male following oral use (598).
Immunologic ...A case of anaphylaxis, with symptoms of hypotension and rash, has been reported following ingestion of a small amount of Panax ginseng syrup (11971).
Neurologic/CNS ...Orally, one of the most common side effects to Panax ginseng is insomnia (589,89734). Headache (594,23638), vertigo, euphoria, and mania (594) have also been reported. Migraine and somnolence occurred in single subjects in a clinical trial (87984). In a case report of a 46-year-old female, orobuccolingual dyskinesia occurred following oral use of a preparation containing black cohosh 20 mg and Panax ginseng 50 mg twice daily for menopausal symptoms. The patient's condition improved once the product was stopped and treatment with baclofen 40 mg and clonazepam 20 mg daily was started (89735).
General
...Orally, intravenously, and topically, vitamin C is well-tolerated.
Most Common Adverse Effects:
Orally: Abdominal cramps, esophagitis, heartburn, headache, osmotic diarrhea, nausea, vomiting. Kidney stones have been reported in those prone to kidney stones. Adverse effects are more likely to occur at doses above the tolerable upper intake level of 2 grams daily.
Topically: Irritation and tingling.
Serious Adverse Effects (Rare):
Orally: There have been rare case reports of carotid inner wall thickening after large doses of vitamin C.
Intravenously: There have been case reports of hyperoxalosis and oxalate nephropathy following high-dose infusions of vitamin C.
Cardiovascular
...Evidence from population research has found that high doses of supplemental vitamin C might not be safe for some people.
In postmenopausal adults with diabetes, supplemental vitamin C intake in doses greater than 300 mg per day is associated with increased risk of cardiovascular mortality. However, dietary intake of vitamin C is not associated with this risk. Also, vitamin C intake is not associated with an increased risk of cardiovascular mortality in patients without diabetes (12498).
Oral supplementation with vitamin C has also been associated with an increased rate of carotid inner wall thickening in men. There is preliminary evidence that supplemental intake of vitamin C 500 mg daily for 18 months can cause a 2.5-fold increased rate of carotid inner wall thickening in non-smoking men and a 5-fold increased rate in men who smoked. The men in this study were 40-60 years old (1355). This effect was not associated with vitamin C from dietary sources (1355).
There is also some concern that vitamin C may increase the risk of hypertension in some patients. A meta-analysis of clinical research suggests that, in pregnant patients at risk of pre-eclampsia, oral intake of vitamin C along with vitamin E increases the risk of gestational hypertension (83450). Other clinical research shows that oral intake of vitamin C along with grape seed polyphenols can increase both systolic and diastolic blood pressure in hypertensive patients (13162).
Dental ...Orally, vitamin C, particularly chewable tablets, has been associated with dental erosion (83484).
Dermatologic ...Topically, vitamin C might cause tingling or irritation at the site of application (6166). A liquid containing vitamin C 20%, red raspberry leaf cell culture extract 0.0005%, and vitamin E 1% (Antioxidant and Collagen Booster Serum, Max Biocare Pty Ltd.) has been reported to cause mild tingling and skin tightness (102355). It is unclear if these effects are due to vitamin C, the other ingredients, or the combination.
Gastrointestinal ...Orally, the adverse effects of vitamin C are dose-related and include nausea, vomiting, esophagitis, heartburn, abdominal cramps, gastrointestinal obstruction, and diarrhea. Doses greater than the tolerable upper intake level (UL) of 2000 mg per day can increase the risk of adverse effects such as osmotic diarrhea and severe gastrointestinal upset (3042,4844,96707,104450). Mineral forms of vitamin C, such as calcium ascorbate (Ester-C), seem to cause fewer gastrointestinal adverse effects than regular vitamin C (83358). In a case report, high dose intravenous vitamin C was associated with increased thirst (96709).
Genitourinary ...Orally, vitamin C may cause precipitation of urate, oxalate, or cysteine stones or drugs in the urinary tract (10356). Hyperoxaluria, hyperuricosuria, hematuria, and crystalluria have occurred in people taking 1 gram or more per day (3042,90943). Supplemental vitamin C over 250 mg daily has been associated with higher risk for kidney stones in males. There was no clear association found in females, but the analysis might not have been adequately powered to evaluate this outcome (104029). In people with a history of oxalate kidney stones, supplemental vitamin C 1 gram per day appears to increase kidney stone risk by 40% (12653). A case of hematuria, high urine oxalate excretion, and the presence of a ureteral stone has been reported for a 9-year-old male who had taken about 3 grams of vitamin C daily since 3 years of age. The condition resolved with cessation of vitamin C intake (90936).
Hematologic ...Prolonged use of large amounts of vitamin C can result in increased metabolism of vitamin C; subsequent reduction in vitamin C intake may precipitate the development of scurvy (15). In one case, a patient with septic shock and a large intraperitoneal hematoma developed moderate hemolysis and increased methemoglobin 12 hours after a high-dose vitamin C infusion. The patient received a blood transfusion and the hemolysis resolved spontaneously over 48 hours (112479).
Neurologic/CNS ...Orally, the adverse effects of vitamin C are dose-related and include fatigue, headache, insomnia, and sleepiness (3042,4844,83475,83476).
Renal ...Hyperoxalosis and oxalate nephropathy have been reported following high-dose infusions of vitamin C. Hyperoxalosis and acute kidney failure contributed to the death of a 76-year-old patient with metastatic adenocarcinoma of the lung who received 10 courses of intravenous infusions containing vitamins, including vitamin C and other supplements over a period of 1 month. Dosages of vitamin C were not specified but were presumed to be high-dose (106618). In another case, a 34-year-old patient with a history of kidney transplant and cerebral palsy was found unresponsive during outpatient treatment for a respiratory tract infection. The patient was intubated for acute hypoxemic respiratory failure, initiated on vasopressors, hydrocortisone, and antibacterial therapy, and received 16 doses of vitamin C 1.5 grams. Serum creatinine level peaked at greater than 3 times baseline and the patient required hemodialysis for oliguria and uncontrolled acidosis. Kidney biopsy revealed oxalate nephropathy with concomitant drug-induced interstitial nephritis (106625). In another case, a 41-year-old patient with a history of kidney transplant presented with fever, nausea, and decreased urine output 4 days after receiving intravenous vitamin C 7 grams for urothelial carcinoma. Serum creatinine levels increased from 1.7 mg/dL to 7.3 mg/dL over those 4 days, and hemodialysis was initiated 3 days after admission due to anuria. Renal biopsy confirmed the diagnosis of acute oxalate nephropathy (109962).
Other ...Intravenously, hypernatremia and falsely elevated ketone levels is reported in a patient with septic shock and chronic kidney disease after a high-dose vitamin C infusion. The hypernatremia resolved over 24 hours after cessation of the infusion (112479).