| Ingredients | Amount Per Serving |
|---|---|
|
(as L-Ascorbic Acid, Rose Hips)
|
240 mg |
|
(Thiamine Mononitrate)
(Thiamin (Form: as Thiamin Mononitrate))
|
10 mg |
|
(Vitamin B2)
|
10 mg |
|
(Niacinamide)
(Niacin (Form: as Niacinamide))
|
50 mg |
|
(Pyridoxine Hydrochloride)
(Vitamin B-6 (Form: as Pyridoxine Hydrochloride))
|
10 mg |
| 800 mcg | |
|
(Cyanocobalamin)
(Vitamin B-12 (Form: as Cyanocobalamin))
|
500 mcg |
| 600 mcg | |
|
(Calcium Pantothenate)
(Pantothenic Acid (Form: as Calcium Pantothenate))
|
20 mg |
Calcium Phosphate (Alt. Name: Ca Phosphate), Vegetable Cellulose, Vegetable Stearic Acid, Silica, Vegetable Magnesium Stearate
Below is general information about the effectiveness of the known ingredients contained in the product B-Complex w/Vitamin C. 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
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
INSUFFICIENT RELIABLE EVIDENCE to RATE
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 B-Complex w/Vitamin C. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
LIKELY SAFE ...when used orally and appropriately. Biotin has been safely used in doses up to 300 mg daily for up to 6 months. A tolerable upper intake level (UL) has not been established (1900,6243,95662,102965). ...when applied topically as cosmetic products at concentrations of 0.0001% to 0.6% biotin (19344).
POSSIBLY SAFE ...when used intramuscularly and appropriately (8468,111366).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Biotin has been safely used at adequate intake doses of 5-25 mcg daily for up to 6 months (173,6243,19347,19348,111365). A tolerable upper intake level (UL) has not been established.
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately.
Biotin has been safely used at the adequate intake (AI) dose of 30 mcg daily during pregnancy and 35 mcg daily during lactation. It has also been used in supplemental doses of up to 300 mcg daily (6243,7878). A tolerable upper intake level (UL) has not been established.
LIKELY SAFE ...when used orally or parenterally and appropriately. Folic acid has been safely used in amounts below the tolerable upper intake level (UL). The UL for folic acid is based only on supplemental folic acid and is expressed in mcg folic acid. Dietary folate is not included in UL calculations, as dietary folate consumption has not been associated with adverse effects. The UL for folic acid in adults is 1000 mcg (6241). In cases of megaloblastic anemia resulting from folate deficiency or malabsorption disorders such as sprue, oral doses of 1-5 mg per day can also be used safely until hematologic recovery is documented, as long as vitamin B12 levels are routinely measured (6241,7725,8739).
POSSIBLY SAFE ...when L-5-methyltetrahydrofolate (L-5-MTHF), the reduced form of folate, is used orally and appropriately, short-term. L-5-MTHF has been used with apparent safety at a dose of 416 mcg daily for 16 weeks (104913,104914) and a dose of 113 mcg daily for 24 weeks (104920). A specific L-5-MTHF product (Metafolin, Eprova) has been used with apparent safety at a dose of 1.3 mg daily for 12 weeks (104912).
POSSIBLY UNSAFE ...when used orally in large doses, long-term. Clinical research shows that taking folic acid daily in doses of 800 mcg to 1200 mcg for 3-10 years significantly increases the risk of developing cancer and adverse cardiovascular effects compared to placebo (12150,13482,16822,17041). Doses above 1 mg per day should also be avoided if possible to prevent precipitation or exacerbation of neuropathy related to vitamin B12 deficiency (6241,6242,6245). However, there is contradictory evidence suggesting that higher doses may not be harmful. There is some evidence that doses of 5 mg per day orally for up to 4 months can be used safely if vitamin B12 levels are routinely measured (7725). Also, other clinical research suggests that folic acid supplementation at doses up to 5 mg, usually in combination with vitamin B12, does not increase the risk of cancer when taken for 2-7 years (91312). Very high doses of 15 mg per day can cause significant central nervous system (CNS) and gastrointestinal side effects (505).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Folic acid has been safely used in children in amounts below the tolerable upper intake level (UL). The ULs for folic acid are based only on supplemental folic acid and are expressed in mcg folic acid. Dietary folate is not included in UL calculations, as dietary folate consumption has not been associated with adverse effects. The UL for children is: 1-3 years of age, 300 mcg; 4-8 years of age, 400 mcg; 9-13 years of age, 600 mcg; 14-18 years of age, 800 mcg (6241).
CHILDREN: POSSIBLY SAFE
when L-5-methyltetrahydrofolate (L-5-MTHF), the reduced form of folate, is used orally and appropriately.
One clinical study in infants aged 27 days and younger shows that consuming a formula containing L-5-MTHF (Metafolin, Merck & Cie) 10.4 mcg/100 mL daily has been used with apparent safety for up to 12 weeks (104918).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately.
Folic acid 300-400 mcg is commonly used during pregnancy for prevention of neural tube defects (8739). Miscarriage rates and negative impacts on fetal growth have not been shown to increase with peri-conception supplemental folic acid intakes of 4 mg per day (91320,91322). However, other research shows that taking more than 5 mg per day during pregnancy may reduce development of cognitive, emotional, and motor skills in infants (91318). Also, the tolerable upper intake level (UL) of folic acid for pregnant or lactating women is 800 mcg daily for those 14-18 years of age and 1000 mcg daily for those 19 years and older (6241).
PREGNANCY AND LACTATION: POSSIBLY SAFE
when L-5-methyltetrahydrofolate (L-5-MTHF), the reduced form of folate, is used orally and appropriately, short-term.
L-5-MTHF has been used with apparent safety at a dose of 416 mcg daily for 16 weeks during lactation. Compared to folic acid, this form seems to further increase the folate concentration of red blood cells, but not breast milk (104913,104914).
LIKELY SAFE ...when prescription products are used orally and appropriately (12033). ...when niacinamide supplements are taken orally in doses below the tolerable upper intake level (UL) set by the Institute of Medicine (IOM). The UL of niacinamide is 30 mg daily for adults 18 years of age and 35 mg daily for adults 19 years and older (6243).
POSSIBLY SAFE ...when used orally in doses greater than 30 mg but less than 900 mg daily. The European Food Safety Authority has set the tolerable upper intake level (UL) of niacinamide at 900 mg daily (104937). However, oral niacinamide has been safely used in doses up to 1500 mg daily for 12 weeks in some clinical trials (25561,94188,98940,107709,110502) and up to 1000 mg daily for 12 months in other trials (93362,113559,113560). ...when used topically and appropriately for up to 16 weeks (5940,93360,110497,110498,110501,113681,113683,113684).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Niacinamide has been safely used in children for up to 7 years in doses below the tolerable upper intake level (UL) (4874,9957). The UL of niacinamide for children by age is: 1-3 years, 10 mg daily; 4-8 years, 15 mg daily; 9-13 years, 20 mg daily; 14-18 years, 30 mg daily (6243).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in amounts that do not exceed the tolerable upper intake level (UL) for niacinamide.
The UL of niacinamide during pregnancy and lactation is 30 mg daily for those 14-18 years of age and 35 mg daily for those 19 years and older (6243). There is insufficient reliable information available about the safety of larger oral doses of niacinamide or topical niacinamide; avoid using.
LIKELY SAFE ...when used orally and appropriately. The pantothenic acid derivative calcium pantothenate has a generally recognized as safe (GRAS) status for use in food products (111258). While a tolerable upper intake level (UL) has not been established, pantothenic has been used in doses of 10-20 grams daily with apparent safety (15,6243,111258) ...when applied topically and appropriately, short-term. The Cosmetic Ingredient Review Expert Panel has concluded that pantothenic acid and its derivatives are safe for use in cosmetic products in concentrations up to 5.3% (111258). Gels or ointments containing a derivative of pantothenic acid, dexpanthenol, at concentrations of up to 5%, have been used safely for up to 30 days (67802,67806,67817).
POSSIBLY SAFE ...when applied intranasally and appropriately, short-term. A dexpanthenol nasal spray has been used with apparent safety up to four times daily for 4 weeks (67826). ...when applied in the eyes appropriately, short-term. Dexpanthenol 5% eyedrops have been used with apparent safety for up to 28 days (67783). ...when injected intramuscularly and appropriately, short-term. Intramuscular injections of dexpanthenol 500 mg daily for up to 5 days or 250 mg weekly for up to 6 weeks have been used with apparent safety (67822,111366).
CHILDREN: LIKELY SAFE
when used orally and appropriately (15,6243).
Calcium pantothenate is generally recognized as safe (GRAS) when used as a food additive and in infant formula (111258). However, a tolerable upper intake level (UL) has not been established (15,6243). ...when applied topically and appropriately (67795,105190,111262). Infant products containing pantothenic acid and its derivatives have been used safely in concentrations of up to 5% for infant shampoos and 2.5% for infant lotions and oils. The Cosmetic Ingredient Review Expert Panel has concluded that pantothenic acid and derivatives are safe for use in topical infant products. (111258).
PREGNANCY: LIKELY SAFE
when used orally and appropriately.
The daily adequate intake (AI) during pregnancy is 6 mg (3094).
LACTATION: LIKELY SAFE
when used orally and appropriately.
The daily adequate intake (AI) during lactation is 7 mg (3094).
LIKELY SAFE ...when used orally and appropriately. Riboflavin 400 mg daily has been taken for up to 3 months, and 10 mg daily has been taken safely for up to 6 months (4912,91752,105480). A tolerable upper intake level (UL) has not been established (3094,91752,94089).
CHILDREN: LIKELY SAFE
when used orally and appropriately in dietary amounts.
A tolerable upper intake level (UL) has not been established (3094,94089). ...when used orally in higher doses for up to 1 year. Doses of 100-200 mg daily have been used safely for 4-12 months in children ages 9-13 years (71483,105484).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately in dietary amounts.
A tolerable upper intake level (UL) has not been established (3094,94089).
LIKELY SAFE ...when used orally and appropriately. A tolerable upper intake level (UL) has not been established for thiamine, and doses up to 50 mg daily have been used without adverse effects (15,6243). ...when used intravenously or intramuscularly and appropriately. Injectable thiamine is an FDA-approved prescription product (15,105445).
CHILDREN: LIKELY SAFE
when used orally and appropriately in dietary amounts.
A tolerable upper intake level (UL) has not been established for healthy individuals (6243).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in dietary amounts of 1.
4 mg daily. A tolerable upper intake level (UL) has not been established for healthy individuals (3094,6243).
LIKELY SAFE ...when used orally, topically, intravenously, intramuscularly, or intranasally and appropriately. Vitamin B12 is generally considered safe, even in large doses (15,1344,1345,1346,1347,1348,2909,6243,7289,7881)(9414,9416,10126,14392,15765,82832,82949,82860,82864,90386)(111334,111551).
PREGNANCY: LIKELY SAFE
when used orally in amounts that do not exceed the recommended dietary allowance (RDA).
The RDA for vitamin B12 during pregnancy is 2.6 mcg daily (6243). There is insufficient reliable information available about the safety of larger amounts of vitamin B12 during pregnancy.
LACTATION: LIKELY SAFE
when used orally in amounts that do not exceed the recommended dietary allowance (RDA).
The RDA of vitamin B12 during lactation is 2.8 mcg daily (6243). There is insufficient reliable information available about the safety of larger amounts of vitamin B12 while breastfeeding.
LIKELY SAFE ...when used orally and appropriately in doses that do not exceed the tolerable upper intake level (UL) of 100 mg daily in the form of pyridoxine for adults (15,6243). ...when used parenterally and appropriately. Injectable vitamin B6 (pyridoxine) is an FDA-approved prescription product (15).
POSSIBLY SAFE ...when used orally and appropriately in doses of 101-200 mg daily (6243,8558).
POSSIBLY UNSAFE ...when used orally in doses at or above 500 mg daily. High doses, especially those exceeding 1000 mg daily or total doses of 1000 grams or more, pose the most risk. However, neuropathy can occur with lower daily or total doses (6243,8195). ...when used intramuscularly in high doses and frequency due to potential for rhabdomyolysis (90795).
CHILDREN: LIKELY SAFE
when used orally and appropriately in doses that do not exceed the tolerable upper intake level (UL) of vitamin B6 in the form of pyridoxine 30 mg daily for children aged 1-3 years, 40 mg daily for 4-8 years, 60 mg daily for 9-13 years, and 80 mg daily for 14-18 years (6243).
CHILDREN: POSSIBLY SAFE
when used orally and appropriately in amounts exceeding the recommended dietary allowance (5049,8579,107124,107125,107135).
CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses, long-term (6243).
PREGNANCY: LIKELY SAFE
when used orally and appropriately.
A special sustained-release product providing vitamin B6 (pyridoxine) 75 mg daily is FDA-approved for use in pregnancy. Vitamin B6 (pyridoxine) is also considered a first-line treatment for nausea and vomiting in pregnancy by the American College of Obstetrics and Gynecology (111601). However, it should not be used long-term or without medical supervision and close monitoring. The tolerable upper intake level (UL) refers to vitamin B6 in the form of pyridoxine and is 80 mg daily for those aged 14-18 years and 100 mg daily for 19 years and older (6243).
PREGNANCY: POSSIBLY UNSAFE
when used orally in excessive doses.
There is some concern that high-dose maternal vitamin B6 (pyridoxine) can cause neonatal seizures (4609,6397,8197).
LACTATION: LIKELY SAFE
when used orally in doses not exceeding the tolerable upper intake level (UL) of vitamin B6 in the form of pyridoxine 80 mg daily for those aged 14-18 years and 100 mg daily for those 19 years and older.
The recommended dietary allowance (RDA) in lactating women is 2 mg daily (6243). There is insufficient reliable information available about the safety of vitamin B6 when used in higher doses in breast-feeding women.
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) and has been used with apparent safety in clinical trials up to 150 mg/kg daily for up to 4 days (114489) and up to 200 mg/kg daily for up to 2 days (114492).
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 B-Complex w/Vitamin C. 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, high doses of folic acid might increase the toxicity of 5-fluorouracil.
 Details
Increases in gastrointestinal side effects of 5-fluorouracil, such as stomatitis and diarrhea, have been described in two clinical studies when leucovorin, a form of folic acid, was administered with 5-fluorouracil (16845).
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Use of high-dose folic acid might contribute to capecitabine toxicity.
Details
Clinical research suggests that higher serum folate levels are associated with an increased risk for moderate or severe toxicity during capecitabine-based treatment for colorectal cancer (105402). Additionally, in one case report, taking folic acid 15 mg daily might have contributed to increased toxicity, including severe diarrhea, vomiting, edema, hand-foot syndrome, and eventually death, in a patient prescribed capecitabine (16837).
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Folic acid might reduce the efficacy of methotrexate as a cancer treatment when given concurrently.
Details
Methotrexate exerts its cytotoxic effects by preventing conversion of folic acid to the active form needed by cells. There is some evidence that folic acid supplements reduce the efficacy of methotrexate in the treatment of acute lymphoblastic leukemia, and theoretically they could reduce its efficacy in the treatment of other cancers (9420). Advise cancer patients to consult their oncologist before using folic acid supplements. In patients treated with long-term, low-dose methotrexate for rheumatoid arthritis (RA) or psoriasis, folic acid supplements can reduce the incidence of side effects, without reducing efficacy (768,2162,4492,4493,4494,4546,9369).
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Folic acid might have antagonistic effects on phenobarbital and increase the risk for seizures.
Details
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Folic acid might reduce serum levels of phenytoin in some patients.
Details
Folic acid may be a cofactor in phenytoin metabolism (4471). Folic acid, in doses of 1 mg daily or more, can reduce serum levels of phenytoin in some patients (4471,4477,4531,4536). Increases in seizure frequency have been reported. If folic acid supplements are added to established phenytoin therapy, monitor serum phenytoin levels closely. If phenytoin and folic acid are started at the same time and continued together, adverse changes in phenytoin pharmacokinetics are avoided (4471,4472,4473,4531). Note that phenytoin also reduces serum folate levels.
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Folic acid might have antagonistic effects on primidone and increase the risk for seizures.
Details
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Folic acid might antagonize the effects of pyrimethamine.
Details
Folic acid can antagonize the antiparasitic effects of pyrimethamine against toxoplasmosis and Pneumocystis carinii pneumonia. Folic acid doesn't antagonize the effects of pyrimethamine in the treatment of malaria, because malarial parasites cannot use exogenous folic acid. Use folinic acid as an alternative to folic acid when indicated (9380).
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Theoretically, niacinamide may have additive effects when used with anticoagulant or antiplatelet drugs, especially in patients on hemodialysis.
Details
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Niacinamide might increase the levels and adverse effects of carbamazepine.
Details
Plasma levels of carbamazepine were increased in two children given high-dose niacinamide, 60-80 mg/kg/day. This might be due to inhibition of the cytochrome P450 enzymes involved in carbamazepine metabolism (14506). There is not enough data to determine the clinical significance of this interaction.
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Niacinamide might increase the levels and adverse effects of primidone.
Details
Case reports in children suggest niacinamide 60-100 mg/kg/day reduces hepatic metabolism of primidone to phenobarbital, and reduces the overall clearance rate of primidone (14506); however, there is not enough data to determine the clinical significance of this potential interaction.
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Theoretically, taking riboflavin with tetracycline antibiotics may decrease the potency of these antibiotics.
Details
In vitro research suggests that riboflavin may inhibit the potency of tetracycline antibiotics (23372). It is not clear if this effect is clinically significant, as this interaction has not been reported in humans.
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Trimethoprim might increase blood levels of thiamine.
Details
In vitro, animal, and clinical research suggest that trimethoprim inhibits intestinal thiamine transporter ThTR-2, hepatic transporter OCT1, and renal transporters OCT2, MATE1, and MATE2, resulting in paradoxically increased thiamine plasma concentrations (111678).
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Theoretically, vitamin B6 might increase the photosensitivity caused by amiodarone.
Details
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Theoretically, vitamin B6 may have additive effects when used with antihypertensive drugs.
Details
Research in hypertensive rats shows that vitamin B6 can decrease systolic blood pressure (30859,82959,83093). Similarly, clinical research in patients with hypertension shows that taking high doses of vitamin B6 may reduce systolic and diastolic blood pressure, possibly by reducing plasma levels of epinephrine and norepinephrine (83091).
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Vitamin B6 may increase the metabolism of levodopa when taken alone, but not when taken in conjunction with carbidopa.
Details
Vitamin B6 (pyridoxine) enhances the metabolism of levodopa, reducing its clinical effects. However, this interaction does not occur when carbidopa is used concurrently with levodopa (Sinemet). Therefore, it is not likely to be a problem in most people (3046).
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High doses of vitamin B6 may reduce the levels and clinical effects of phenobarbital.
Details
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High doses of vitamin B6 may reduce the levels and clinical effects of phenytoin.
Details
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High-dose vitamin C might slightly prolong the clearance of acetaminophen.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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.
Details
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 B-Complex w/Vitamin C. 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 and topically, biotin is generally well tolerated.
Most Common Adverse Effects: None.
Gastrointestinal ...Orally, high-dose biotin has been rarely associated with mild diarrhea. Transient mild diarrhea was reported by 2 patients taking biotin 300 mg daily (95662).
Pulmonary/Respiratory ...In one case report in France, a 76-year-old female frequent traveler developed eosinophilic pleuropericarditis after taking biotin 10 mg and pantothenic acid 300 mg daily for 2 months. She had also been taking trimetazidine for 6 years (3914). Whether eosinophilia in this case was related to biotin, pantothenic acid, other substances, or patient-specific conditions is unknown. There have been no other similar reports.
General
...Orally, folic acid is generally well-tolerated in amounts found in fortified foods, as well as in supplemental doses of less than 1 mg daily.
Most Common Adverse Effects:
Orally: At doses of 5 mg daily - abdominal cramps, diarrhea, and rash. At doses of 15 mg daily - bitter taste, confusion, hyperactivity, impaired judgment, irritability, nausea, sleep disturbances.
Serious Adverse Effects (Rare):
Orally: Cancer (long-term use), cardiovascular complications, liver injury, seizures.
All ROAs: Allergic reactions such as bronchospasm and anaphylactic shock.
Cardiovascular ...There is some concern that high oral doses of folic acid might increase the risk of adverse cardiovascular outcomes. Clinical research shows that taking doses of 800 mcg to 1.2 mg/day might increase the risk of adverse cardiovascular events in patients with cardiovascular disease (12150,13482). High doses of folic acid might promote cell growth by providing large amounts of the biochemical precursors needed for cell replication. Overgrowth of cells in the vascular wall might increase the risk of occlusion (12150). Although some research suggests that use of folic acid might increase the need for coronary revascularization, analysis of multiple studies suggests that taking folic acid up to 5 mg/day for up to 24 months does not appear to affect coronary revascularization risk (90798).
Dermatologic ...Orally, folic acid 1-5 mg daily can cause rash (7225,90375,91319). Folic acid 15 mg daily can sometimes cause allergic skin reactions (15).
Gastrointestinal ...Orally, folic acid 5 mg daily can cause abdominal cramps and diarrhea (7225). Folic acid 15 mg daily can sometimes cause nausea, abdominal distention, flatulence, and bitter taste in the mouth (15). In children aged 6-30 months at risk of malnourishment, taking a nutritional supplement (Nutriset Ltd) enriched in folic acid 75-150 mcg daily, with or without vitamin B 12 0.9-1.8 mcg daily, for 6 months increases the likelihood of having persistent diarrhea (90391).
Hepatic ...Liver dysfunction, with jaundice and very high liver enzymes, occurred in a 30-year-old pregnant patient with severe nausea and vomiting taking a folic acid supplement (Folic acid, Nature Made) 400 mcg daily. Based on the timing of ingestion, the lack of other etiological factors, a positive drug-induced lymphocyte stimulation test, and liver function normalization once the folic acid had been stopped, the authors suggest the folic acid supplement was the cause. However, the authors did not determine which substance in the folic acid supplement was responsible and therefore it cannot be determined that folic acid itself was the cause (91309).
Neurologic/CNS ...Orally, folic acid 15 mg daily can sometimes cause altered sleep patterns, vivid dreaming, irritability, excitability, hyperactivity, confusion, and impaired judgment (15). Large doses of folic acid can also precipitate or exacerbate neuropathy in people deficient in vitamin B12 (6243). Use of folic acid for undiagnosed anemia has masked the symptoms of pernicious anemia, resulting in lack of treatment and eventual neurological damage (15). Patients should be warned not to self-treat suspected anemia. There is also some concern that consuming high amounts of folic acid from the diet and/or supplements might worsen cognitive decline in older people. A large-scale study suggests that people over 65 years of age, who consume large amounts of folic acid (median of 742 mcg/day), have cognitive decline at a rate twice as fast as those consuming smaller amounts (median of 186 mcg/day). It's not known if this is directly attributable to folic acid. It is theorized that it could be due to folic acid masking a vitamin B12 deficiency. Vitamin B12 deficiency is associated with cognitive decline (13068). More evidence is needed to determine the significance of this finding. For now, suggest that most patients aim for the recommended folic acid intake of 400 mcg/day.
Oncologic
...There is some concern that high dose folic acid might increase the risk of cancer, although research is unclear and conflicting.
A large-scale population study suggests that taking a multivitamin more than 7 times per week with a separate folic acid supplement significantly increased the risk of prostate cancer (15607). Clinical research also shows that taking folic acid 1 mg daily increase the absolute risk of prostate cancer by 6.4% over a 10-year period when compared with placebo. However, those with a higher baseline dietary intake of folic acid had a lower rate of prostate cancer, but this was not statistically significant. Also, folate and folic acid intake in patients with prostate cancer is not associated with the risk of prostate cancer recurrence after radical prostatectomy (91317). However, it is possible that discrepancies are due to dietary folate versus folic acid intake. Large analyses of population studies suggest that while dietary folate/folic acid is not associated with prostate cancer, high blood folate/folic acid increases the risk of prostate cancer (50411,91316).
Additional clinical research shows that taking folic acid 800 mcg daily, in combination with vitamin B12 400 mcg, significantly increases the risk of developing cancer, especially lung cancer, and all-cause mortality in patients with cardiovascular disease (17041). However, this may be due to vitamin B12, as other observational research found that higher vitamin B12 levels are linked with an increased risk for lung cancer (102383). Meta-analyses of large supplementation trials of folic acid at levels between 0.5-2.5 mg daily also suggest an increased risk of cancer (50497,110318). Also, in elderly individuals, taking folic acid 400 mcg daily with vitamin B12 500 mcg daily increased the risk of cancer. The risk was highest in individuals over 80 years of age and in females and mainly involved gastrointestinal and colorectal cancers (90393).
Not all researchers suspect that high intake of folic acid supplements might be harmful. Some research suggests that increased dietary intake of folic acid, along with other nutrients, might be protective against cancer (16822). A meta-analysis of multiple clinical trials suggests that folic acid supplementation studies with folic acid levels between 500 mcg to 50 mg/day does not increase the risk of general or site-specific cancer for up to 7 years (91312,91321). Also, a post-hoc subgroup analysis of results from clinical research in adults with a history of recent stroke or ischemic attack suggests that taking folic acid, vitamin B12, and vitamin B6 does not increase cancer risk overall, although it was associated with an increased risk of cancer in patients who also had diabetes (90378).
Psychiatric ...Orally, folic acid 15 mg daily can sometimes cause exacerbation of seizure frequency and psychotic behavior (15).
Pulmonary/Respiratory ...Folic acid use in late pregnancy has been associated with an increased risk of persistent and childhood asthma at 3. 5 years in population research (50380). When taken pre-pregnancy or early in pregnancy, population research has not found an association with increased risk of asthma or allergies in childhood (90799,103979). Folic acid use in pregnancy has been associated with a slightly increased risk of wheeze and lower respiratory tract infections up to 18 months of age in population research (50328).
General
...Orally, niacinamide is well tolerated in amounts typically found in food.
When used topically and orally in higher doses, niacinamide seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Dizziness, drowsiness, itching, gastrointestinal disturbances, headache, and rash.
Topically: Burning sensation, itching, and mild dermatitis.
Dermatologic ...Orally, large doses of niacinamide are associated with occasional reports of rashes, itching, and acanthosis nigricans (4880,11695,11697,14504,107709), though a meta-analysis of 19 clinical studies suggests that dermatological adverse event rates are similar between niacinamide and control (110497). Topically, application of niacinamide in a cream has been reported to cause a burning sensation, itching and pruritus, crusting, and mild dermatitis (93357,93360,110501,110498).
Endocrine ...Orally, niacinamide in high doses, 50 mg/kg daily, has been associated with modestly higher insulin requirements in patients with type 1 diabetes, when compared with taking niacinamide 25 mg/kg daily. Theoretically, high-dose niacinamide might increase insulin resistance, although to a lesser extent than niacin (4881,14512).
Gastrointestinal ...Orally, large doses of niacinamide can cause gastrointestinal disturbances including nausea, vomiting, heartburn, anorexia, epigastric pain, flatulence, and diarrhea (6243,11694,11695,11696,11697,107709,110497,113682).
Hematologic ...Orally, niacinamide supplementation might increase the risk for thrombocytopenia in patients undergoing hemodialysis (98940,107709). A meta-analysis of small clinical studies shows that taking niacinamide during hemodialysis to reduce phosphate levels is associated with a 2.8-fold increased risk for thrombocytopenia when compared with placebo. In one of the included studies, platelet levels returned to normal within 20 days after niacinamide discontinuation (98940).
Hepatic ...Orally, older reports of elevated liver function tests with high doses of niacinamide (3 grams or more daily) have raised concerns about liver toxicity. However, newer studies have not reported this concern; it is possible that some of these cases were due to contamination with niacin (4880,11694,11695,14503).
Neurologic/CNS ...Orally, large doses of niacinamide can cause dizziness, drowsiness, and headaches (11694,11695,11696,11697,107709).
General
...Orally, pantothenic acid is generally well tolerated.
Topically and intramuscularly, dexpanthenol, a synthetic form of pantothenic acid, seems to be well tolerated.
Most Common Adverse Effects:
Topically: Burning, contact dermatitis, eczema, irritation, and itching related to dexpanthenol.
Cardiovascular ...There is one case of eosinophilic pleuropericardial effusion in a patient taking pantothenic acid 300 mg per day in combination with biotin 10 mg per day for 2 months (3914).
Dermatologic ...Topically, dexpanthenol has been associated with itching, burning, skin irritation, contact dermatitis, and eczema (67779,67781,67788,111258,111262). Three cases of allergic contact dermatitis have been reported (111260,111261).
Gastrointestinal ...Orally, pantothenic acid has been associated with diarrhea (67822,111258).
General
...Orally, riboflavin is generally well tolerated.
Most Common Adverse Effects:
Orally: Dose-related nausea and urine discoloration.
Gastrointestinal ...Orally, riboflavin has been associated with rare diarrhea and dose-related nausea (1398,71483). In one clinical study, one subject out of 28 reported having diarrhea two weeks after starting riboflavin 400 mg daily (1398).
Genitourinary ...Orally, high doses of riboflavin can cause bright yellow urine. Furthermore, in one clinical study, one subject out of 28 reported polyuria two weeks after starting riboflavin 400 mg daily (1398,3094).
General
...Orally and parenterally, thiamine is generally well tolerated.
Serious Adverse Effects (Rare):
Parenterally: Hypersensitivity reactions including angioedema and anaphylaxis.
Immunologic
...Orally, thiamine might rarely cause dermatitis and other allergic reactions.
Parenterally, thiamine can cause anaphylactoid and hypersensitivity reactions, but this is also rare (<0.1%). Reported symptoms and events include feelings of warmth, tingling, pruritus, urticaria, tightness of the throat, cyanosis, respiratory distress, gastrointestinal bleeding, pulmonary edema, angioedema, hypotension, and death (15,35585,105445).
In one case report, a 46-year-old female presented with systemic allergic dermatitis after applying a specific product (Inzitan, containing lidocaine, dexamethasone, cyanocobalamin and thiamine) topically by iontophoresis; the allergic reaction was attributed to thiamine (91170).
General
...Orally, intramuscularly, and topically, vitamin B12 is generally well-tolerated.
Most Common Adverse Effects:
Intramuscular: Injection site reactions.
Serious Adverse Effects (Rare):
Intramuscularly: Severe hypokalemia has been rarely linked with correction of megaloblastic anemia with vitamin B12.
Cardiovascular ...In human clinical research, an intravenous loading dose of folic acid, vitamin B6, and vitamin B12, followed by daily oral administration after coronary stenting, increased restenosis rates (12150). Hypertension following intravenous administration of hydroxocobalamin has been reported in human research (82870,82864).
Dermatologic
...Orally or intramuscularly, vitamin B12 can cause allergic reactions such as rash, pruritus, erythema, and urticaria.
Theoretically, allergic reactions might be caused by the cobalt within the vitamin B12 molecule (82864,90373,90381,103974). In one case report, oral methylcobalamin resulted in contact dermatitis in a 59-year-old Japanese female with a cobalt allergy (103974). In another case report, a 69-year-old female developed a symmetrical erythematous-squamous rash for 5 years after oral vitamin B12 supplementation for 10 years. A patch test confirmed that the systemic allergic dermatitis was due to vitamin B12 supplementation, which resolved 3 months after discontinuation (114578).
Vitamin B12 (intramuscular or oral) has also been associated with at least 19 cases of acneiform eruptions which resolved upon discontinuation of vitamin B12 (90365,90369,90388). High-dose vitamin B12 (20 mcg daily) and vitamin B6 (80 mg daily) have been associated with cases of rosacea fulminans characterized by intense erythema with nodules, papules, and pustules. Symptoms may last up to four months after the supplement is stopped and can be treated with systemic corticosteroids and topical therapy (10998,82870,82871).
Gastrointestinal ...Intravenously, vitamin B12 (hydroxocobalamin) 2. 5-10 grams can cause nausea and dysphagia (82864).
Genitourinary ...Intravenously, vitamin B12 (hydroxocobalamin) 5-15 grams has been associated with chromaturia in clinical research (82870,82871,112282,112264).
Hematologic ...According to case report data, the correction of megaloblastic anemia with vitamin B12 may result in fatal hypokalemia (82914).
Musculoskeletal ...According to case report data, correction of megaloblastic anemia with vitamin B12 has precipitated gout in susceptible individuals (82879).
Neurologic/CNS ...Treatment with vitamin B12 has been rarely associated with involuntary movements in infants with vitamin B12 deficiency (90370,90385,90397). In some cases these adverse reactions were misdiagnosed as seizures or infantile tremor syndrome (90370,90385). These adverse reactions presented 2-5 days after treatment with vitamin B12 and resolved once vitamin B12 was discontinued (90370,90385,90397).
Oncologic ...Although some epidemiological research disagrees (9454), most research has found that elevated plasma levels of vitamin B12 are associated with an increased risk of various types of cancer, including lung and prostate cancers and solid tumors (50411,102383,107743). One study found, when compared with blood levels of vitamin B12 less than 1000 ng/mL, plasma vitamin B12 levels of at least 1000 ng/mL was strongly associated with the occurrence of solid cancer (107743). It is unclear if increased intake of vitamin B12, either through the diet or supplementation, directly affects the risk of cancer. It is possible that having cancer increases the risk of vitamin B12 elevation. However, one observational study has found that the highest quintile of dietary intake of vitamin B12 is associated with a 75% increased incidence of developing esophageal cancer when compared with the lowest quintile in never drinkers, but not drinkers (107147).
Renal ...There is a case report of oxalate nephropathy in a 54-year-old male which was determined to be related to the use of intravenous hydroxocobalamin as treatment for cyanide poisoning. Intermittent hemodialysis was started 5 days after admission, along with a low-oxalate diet, oral calcium acetate, and pyridoxine 5 mg/kg daily (107148). A review of the use of intravenous hydroxocobalamin for suspected cyanide poisoning in 21 intensive care units in France between 2011 and 2017 resulted in a 60% increased odds of acute kidney injury and a 77% increased odds of severe acute kidney injury in the first week. However, biopsies were not conducted and a direct link with use of hydroxocobalamin could not be made (107139).
Other ...Several studies have found that higher vitamin B12 levels may be associated with increased mortality or decreased survival rates in hospitalized elderly patients (82889,82812,82857,82895). Human research has also found a positive correlation between vitamin B12 status and all-cause mortality in Pima Indians with diabetes (82863).
General
...Orally or by injection, vitamin B6 is well tolerated in doses less than 100 mg daily.
Most Common Adverse Effects:
Orally or by injection: Abdominal pain, allergic reactions, headache, heartburn, loss of appetite, nausea, somnolence, vomiting.
Serious Adverse Effects (Rare):
Orally or by injection: Sensory neuropathy (high doses).
Dermatologic ...Orally, vitamin B6 (pyridoxine) has been linked to reports of skin and other allergic reactions and photosensitivity (8195,9479,90375). High-dose vitamin B6 (80 mg daily as pyridoxine) and vitamin B12 (20 mcg daily) have been associated with cases of rosacea fulminans characterized by intense erythema with nodules, papules, and pustules. Symptoms may persist for up to 4 months after the supplement is stopped, and may require treatment with systemic corticosteroids and topical therapy (10998).
Gastrointestinal ...Orally or by injection, vitamin B6 (pyridoxine) can cause nausea, vomiting, heartburn, abdominal pain, mild diarrhea, and loss of appetite (8195,9479,16306,83064,83103,107124,107127,107135). In a clinical trial, one patient experienced infectious gastroenteritis that was deemed possibly related to taking vitamin B6 (pyridoxine) orally up to 20 mg/kg daily (90796). One small case-control study has raised concern that long-term dietary vitamin B6 intake in amounts ranging from 3.56-6.59 mg daily can increase the risk of ulcerative colitis (3350).
Hematologic ...Orally or by injection, vitamin B6 (pyridoxine) can cause decreased serum folic acid concentrations (8195,9479). One case of persistent bleeding of unknown origin has been reported in a clinical trial for a patient who used vitamin B6 (pyridoxine) 100 mg twice daily on days 16 to 35 of the menstrual cycle (83103). It is unclear if this effect was due to vitamin B6 intake.
Musculoskeletal ...Orally or by injection, vitamin B6 (pyridoxine) can cause breast soreness or enlargement (8195).
Neurologic/CNS ...Orally or by injection, vitamin B6 (pyridoxine) can cause headache, paresthesia, and somnolence (8195,9479,16306). Vitamin B6 (pyridoxine) can also cause sensory neuropathy, which is related to daily dose and duration of intake. Doses exceeding 1000 mg daily or total doses of 1000 grams or more pose the most risk, although neuropathy can occur with lower daily or total doses as well (8195). The mechanism of the neurotoxicity is unknown, but is thought to occur when the liver's capacity to phosphorylate pyridoxine via the active coenzyme pyridoxal phosphate is exceeded (8204). Some researchers recommend taking vitamin B6 as pyridoxal phosphate to avoid pyridoxine neuropathy, but its safety is unknown (8204). Vitamin B6 (pyridoxine) neuropathy is characterized by numbness and impairment of the sense of position and vibration of the distal limbs, and a gradual progressive sensory ataxia (8196,10439). The syndrome is usually reversible with discontinuation of pyridoxine at the first appearance of neurologic symptoms. Residual symptoms have been reported in patients taking more than 2 grams daily for extended periods (8195,8196). Daily doses of 100 mg or less are unlikely to cause these problems (3094).
Oncologic ...In females, population research has found that a median intake of vitamin B6 1. 63 mg daily is associated with a 3.6-fold increased risk of rectal cancer when compared with a median intake of 1.05 mg daily (83024). A post-hoc subgroup analysis of results from clinical research in adults with a history of recent stroke or ischemic attack suggests that taking folic acid, vitamin B12, and vitamin B6 does not increase cancer risk overall, although it was associated with an increased risk of cancer in patients who also had diabetes (90378). Also, in patients with nasopharyngeal carcinoma, population research has found that consuming at least 8.6 mg daily of supplemental vitamin B6 during treatment was associated with a lower overall survival rate over 5 years, as well as a reduced progression-free survival, when compared with non-users and those with intakes of up to 8.6 mg daily (107134).
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). Three cases of transient hypotension and tachycardia during intravenous administration of vitamin C have also been reported (114490).
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 (3042,4844,96707,104450,114493,114490). 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).
