| Ingredients | Amount Per Serving |
|---|---|
| 540 mg | |
|
Ester C
(Calcium Ascorbate)
|
675 mg |
|
(Ca)
|
75 mg |
|
(Pine bark)
(dried extract)
(Pycnogenol (Alt. Name: Pine bark) Note: dried extract )
|
3 mg |
|
Rutin N.F.
|
50 mg |
|
Bioflavonoids
|
50 mg |
|
Proprietary Blend {Combination}
|
6 mg |
|
(root)
|
|
Cellulose, Gelatin Note: capsule, Vegetable Stearate
Below is general information about the effectiveness of the known ingredients contained in the product Ester C Plus. 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
Below is general information about the safety of the known ingredients contained in the product Ester C Plus. 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. Beta-carotene supplements are appropriate for certain specific conditions; however, beta-carotene supplementation is not recommended for the general population (4844,6393). There is no tolerable upper intake level (UL) set for beta-carotene. However, doses as low as 20 mg/day have been associated with increased risk of lung and prostate cancer in people who smoke (1371,3359,3937,3959,6393,11786). There is also concern that taking high doses of antioxidants such as beta-carotene might do more harm than good. In several analyses of clinical studies involving smokers and healthy non-smokers, taking beta-carotene supplements alone or in combination with other antioxidants is associated with an increased risk of mortality from all causes (15305,34514,90775).
POSSIBLY UNSAFE ...when used orally in high doses or in people who smoke or have a history of asbestos exposure. Supplemental beta-carotene 20 mg daily for 5-8 years seems to increase the risk of lung cancer, prostate cancer, intracerebral hemorrhage, and cardiovascular and total mortality in people who smoke cigarettes or have a history of high-level exposure to asbestos (1371,3359,3937,3959,6393,11786,34591). There is also concern that taking high doses of antioxidants such as beta-carotene might do more harm than good in the general population. In several analyses of clinical studies involving smokers and healthy non-smokers, taking beta-carotene supplements alone or in combination with other antioxidants is associated with an increased risk of mortality from all causes (15305,34514,90775). Beta-carotene from foods does not seem to have this effect.
CHILDREN: LIKELY SAFE
when used orally and appropriately (4844).
High doses (greater than 60 mg per day) have been used with apparent safety for specific conditions such as erythropoietic protoporphyria (11793).
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (4844,6393).
There is insufficient reliable information available about the safety of large doses of beta-carotene in pregnancy and lactation.
LIKELY SAFE ...when used orally or intravenously and appropriately. Calcium is safe when used in appropriate doses (7555,12928,12946,95817). However, excessive doses should be avoided. The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: Age 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg; 19-50 years, 2500 mg; 51+ years, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stone, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Other clinical studies suggest that, when combined with vitamin D supplementation, calcium supplementation is not associated with an increased risk of CVD, CHD, or MI (93533,107231). Other analyses report conflicting results and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients not to consume more than the recommended daily intake of 1000-1200 mg per day, to consider total calcium intake from both dietary and supplemental sources (17484), and to combine calcium supplementation with vitamin D supplementation (93533).
POSSIBLY UNSAFE ...when used orally in excessive doses. The National Academy of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 19-50 years, 2500 mg; 51 years and older, 2000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome. There has also been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these studies, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Other clinical studies suggest that, when combined with vitamin D supplementation, calcium supplementation is not associated with an increased risk of CVD, CHD, or MI (93533,107231). Other analyses report conflicting results and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Advise patients to not consume more than the recommended daily intake of 1000-1200 mg per day, to consider total calcium intake from both dietary and supplemental sources (17484), and to combine calcium supplementation with vitamin D supplementation (93533).
CHILDREN: LIKELY SAFE
when used orally and appropriately.
Calcium is safe when used in appropriate doses (17506).
CHILDREN: POSSIBLY UNSAFE
when used orally in excessive doses.
The Institute of Medicine sets the daily tolerable upper intake level (UL) for calcium according to age as follows: 0-6 months, 1000 mg; 6-12 months, 1500 mg; 1-8 years, 2500 mg; 9-18 years, 3000 mg (17506). Doses over these levels can increase the risk of side effects such as kidney stones, hypercalciuria, hypercalcemia, and milk-alkali syndrome.
PREGNANCY AND LACTATION: LIKELY SAFE
when used orally and appropriately (945,1586,3263,3264,17506).
The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia (97347).
PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally in excessive doses.
The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg (17506). Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures (97345).
LIKELY SAFE ...when used orally and appropriately, short-term. Various liquid extracts of Echinacea purpurea have been used safely for up to 10 days, including EchinaGuard (Madaus AG) 20 drops every 2 hours for 1 day, then three times daily (10320), or Echinilin (Inovobiologic Inc.) 40 mL in divided doses for 1 day, then 15 mL in divided doses daily thereafter (12355,20062). Other liquid extracts have been used safely for relatively longer periods, including Echinaforce (A. Vogel Bioforce AG) 2.4 grams daily for 4 months or 1.6 grams daily for 6 months (7087,18225), and Echinacin (Madaus AG) 5 mL twice daily for 10 days, or 4 mL twice daily for 8 weeks (3282,10802). Specific solid dosage forms of echinacea that have been used safely for up to 10 days include Echinacea purpurea above-ground parts (EchinaFresh, Enzymatic Therapy) 300 mg daily (11970), and mixtures of Echinacea purpurea and Echinacea angustifolia herb in divided doses of 6 grams to 10.5 grams for 1 day then 3 grams to 5.1 grams daily (10800,17519,20059). A specific Echinacea angustifolia extract (ExtractumPharma ZRT) has also been used with apparent safety at a dose of 40 mg once or twice daily for up to 7 days (20064,103233). An Echinacea purpurea product (Natures Resource) has been used safely at a dose of 1.8 grams daily for 8 weeks (17521), and echinacea (Puritan's Pride) has been used safely at 8 grams daily for 28 days (20066).
POSSIBLY SAFE ...when used topically, short-term. A specific cream (Linola Plus Cream, Dr. August Wolff GmbH & Co.) containing echinacea extract (WO 3260) has been applied to the skin safely 2-3 times daily for up to 12 weeks (97499). There is insufficient reliable evidence about the safety of echinacea when used parenterally.
CHILDREN: POSSIBLY SAFE
when used orally, short-term.
Some clinical research shows that an extract of the above-ground parts of Echinacea purpurea (EC31J2, Echinacin Saft, Madaus AG) in a dose of 3.75 mL twice daily (for ages 2 years to 5 years) or 7.5 mL twice daily (for ages 6 years to 11 years) is safe when used for up to 10 days (4989). However, about 7% of children experienced a rash after taking echinacea, which might have been caused by an allergic reaction (4989). There is concern that allergic reactions could be severe in some children. The Medicines and Healthcare Products Regulatory Agency in the United Kingdom recommends against the use of oral echinacea products in children under 12 years of age due to this risk of allergic reaction (18207). In contrast, another clinical study in children 4-12 years old shows that a specific Echinacea purpurea product (Echinaforce Junior, A. Vogel) does not cause allergic or urticarial reactions more frequently than vitamin C (105719).
PREGNANCY: POSSIBLY SAFE
when used orally, short-term.
There is preliminary evidence that mothers can safely use echinacea in the form of E. purpurea or E. angustifolia solid dosage forms, 250-1000 mg daily, or tinctures, up to 30 drops daily, for 5 days to 7 days during the first trimester without adversely affecting the fetus (7056,13418,15123). There is insufficient reliable information available about the safety of echinacea when used for longer than 7 days.
LACTATION:
Insufficient reliable information available; avoid using.
POSSIBLY SAFE ...when used orally and appropriately. A standardized extract of maritime pine bark (Pycnogenol, Horphag Research) has been safely used in doses of 50-450 mg daily for up to one year (2435,2451,2462,2554,2556,7693,10214,10416,12012,14899) (15424,15521,15522,15523,15524,100359,105782). The same extract has also been used with apparent safety in a dose of 800 mg daily for 16 days (103617). A different standardized extract of maritime pine bark (Oligopin, DRT Group) has been used with apparent safety in doses of up to 150 mg daily for up to 12 weeks (105781,105783). ...when applied topically as a cream or powder. A standardized extract of maritime pine bark (Pycnogenol, Horphag Research) 0.5% cream has been used for up to 7 days (50912). Powder from a standardized extract of maritime pine bark (Pycnogenol, Horphag Research) 100 mg has been applied to the skin daily for up to 6 weeks (50887,50896).
CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term.
A standardized extract of maritime pine bark (Pycnogenol, Horphag Research), administered in a dose of 1 mg/lb body weight daily, has been safely used in a clinical study of children aged 6-18 years for up to 3 months (13120).
PREGNANCY: POSSIBLY SAFE
when used orally during the third trimester of pregnancy.
In one small clinical study, a standardized extract of maritime pine bark (Pycnogenol, Horphag Research) has been used at a dose of 30 mg daily with apparent safety during the third trimester of pregnancy (15423). However, more evidence is needed; use cautiously or avoid using.
LACTATION:
There is insufficient reliable information available regarding the safety of maritime pine when used during lactation; avoid using.
POSSIBLY SAFE ...when used orally and appropriately, short-term. Quercetin has been used with apparent safety in doses up to 1 gram daily for up to 12 weeks (481,1998,1999,16418,16429,16430,16431,96774,96775,96782)(99237,102539,102540,102541,104229,104679,106498,106499,107450,109620)(109621). ...when used intravenously and appropriately. Quercetin has been used with apparent safety in doses less than 945 mg/m2. Higher doses have been reported to cause nephrotoxicity (9564,16418). There is insufficient reliable information available about the safety of quercetin when used topically.
POSSIBLY UNSAFE ...when used intravenously in large amounts. Doses greater than 945 mg/m2 have been reported to cause nephrotoxicity (9564,16418).
PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.
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 Ester C Plus. Some ingredients may not be listed. This information does NOT represent a recommendation for or a test of this specific product as a whole.
Beta-carotene might decrease the beneficial effects of niacin on high-density lipoprotein (HDL) cholesterol levels.
 Details
A combination of niacin and simvastatin (Zocor) effectively raises high-density lipoprotein (HDL) cholesterol levels in patients with coronary disease and low HDL levels. Clinical research shows that taking a combination of antioxidants (beta-carotene, vitamin C, vitamin E, and selenium) along with niacin and simvastatin 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 beta-carotene, or to the combination. It also is not known whether it will occur in other patient populations.
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Calcium citrate might increase aluminum absorption and toxicity. Other types of calcium do not increase aluminum absorption.
Details
Calcium citrate can increase the absorption of aluminum when taken with aluminum hydroxide. The increase in aluminum levels may become toxic, particularly in individuals with kidney disease (21631). However, the effect of calcium citrate on aluminum absorption is due to the citrate anion rather than calcium cation. Calcium acetate does not appear to increase aluminum absorption (93006).
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Calcium reduces the absorption of bisphosphonates.
Details
Advise patients to take bisphosphonates at least 30 minutes before calcium, but preferably at a different time of day. Calcium supplements decrease absorption of bisphosphonates (12937).
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Taking calcipotriene with calcium might increase the risk for hypercalcemia.
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Calcipotriene is a vitamin D analog used topically for psoriasis. It can be absorbed in sufficient amounts to cause systemic effects, including hypercalcemia (12938). Theoretically, combining calcipotriene with calcium supplements might increase the risk of hypercalcemia.
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Intravenous calcium may decrease the effects of calcium channel blockers; oral calcium is unlikely to have this effect.
Details
Intravenous calcium is used to decrease the effects of calcium channel blockers in the management of overdose. Intravenous calcium gluconate has been used before intravenous verapamil (Isoptin) to prevent or reduce the hypotensive effects without affecting the antiarrhythmic effects (6124). But there is no evidence that dietary or supplemental calcium when taken orally interacts with calcium channel blockers (12939,12947).
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Co-administration of intravenous calcium and ceftriaxone can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys.
Details
Avoid administering intravenous calcium in any form, such as parenteral nutrition or Lactated Ringers, within 48 hours of intravenous ceftriaxone. Case reports in neonates show that administering intravenous ceftriaxone and calcium can result in precipitation of a ceftriaxone-calcium salt in the lungs and kidneys. In several cases, neonates have died as a result of this interaction (15794,21632). So far there are no reports in adults; however, there is still concern that this interaction might occur in adults.
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Using intravenous calcium with digoxin might increase the risk of fatal cardiac arrhythmias.
Details
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Theoretically, calcium may reduce the therapeutic effects of diltiazem.
Details
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, calcium might increase this risk of hypercalcemia and reduce the effectiveness of diltiazem.
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Calcium seems to reduce levels of dolutegravir.
Details
Advise patients to take dolutegravir either 2 hours before or 6 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium carbonate 1200 mg concomitantly with dolutegravir 50 mg reduces plasma levels of dolutegravir by almost 40%. Calcium appears to decrease levels of dolutegravir through chelation (93578).
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Calcium seems to reduce levels of elvitegravir.
Details
Advise patients to take elvitegravir either 2 hours before or 2 hours after taking calcium supplements. Pharmacokinetic research suggests that taking calcium along with elvitegravir can reduce blood levels of elvitegravir through chelation (94166).
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Calcium seems to reduce the absorption and effectiveness of levothyroxine.
Details
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Theoretically, concomitant use of calcium and lithium may increase this risk of hypercalcemia.
Details
Clinical research suggests that long-term use of lithium may cause hypercalcemia in 10% to 60% of patients (38953). Theoretically, concomitant use of lithium and calcium supplements may further increase this risk.
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Calcium seems to reduce the absorption of quinolone antibiotics.
Details
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Calcium may reduce levels of raltegravir.
Details
Pharmacokinetic research shows that taking a single dose of calcium carbonate 3000 mg along with raltegravir 400 mg twice daily modestly decreases the mean area under the curve of raltegravir, but the decrease does not necessitate a dose adjustment of raltegravir (94164). However, a case of elevated HIV-1 RNA levels and documented resistance to raltegravir has been reported for a patient taking calcium carbonate 1 gram three times daily plus vitamin D3 (cholecalciferol) 400 IU three times daily in combination with raltegravir 400 mg twice daily for 11 months. It is thought that calcium reduced raltegravir levels by chelation, leading to treatment failure (94165).
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Calcium seems to reduce the absorption of sotalol.
Details
Advise patients to separate doses by at least 2 hours before or 4-6 hours after calcium. Calcium appears to reduce the absorption of sotalol, probably by forming insoluble complexes (10018).
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Calcium seems to reduce the absorption of tetracycline antibiotics.
Details
Advise patients to take oral tetracyclines at least 2 hours before, or 4-6 hours after calcium supplements. Taking calcium at the same time as oral tetracyclines can reduce tetracycline absorption. Calcium binds to tetracyclines in the gut (1843).
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Taking calcium along with thiazides might increase the risk of hypercalcemia and renal failure.
Details
Thiazides reduce calcium excretion by the kidneys (1902). Using thiazides along with moderately large amounts of calcium carbonate increases the risk of milk-alkali syndrome (hypercalcemia, metabolic alkalosis, renal failure). Patients may need to have their serum calcium levels and/or parathyroid function monitored regularly.
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Theoretically, calcium may reduce the therapeutic effects of verapamil.
Details
Hypercalcemia can reduce the effectiveness of verapamil in atrial fibrillation (10574). Theoretically, use of calcium supplements may increase this risk of hypercalcemia and reduce the effectiveness of verapamil.
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Echinacea can increase plasma levels of caffeine by inhibiting its metabolism.
Details
Echinacea seems to increase plasma concentrations of caffeine by around 30% (12155). This is likely due to inhibition of cytochrome P450 1A2 (CYP1A2) by echinacea.
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Echinacea might inhibit the metabolism of CYP1A2 and increase plasma levels of some drugs.
Details
Echinacea appears to inhibit CYP1A2 enzymes in humans. Additionally, echinacea seems to increase plasma concentrations of caffeine, a CYP1A2 substrate, by around 30% (12155). Theoretically, echinacea might increase levels of other drugs metabolized by CYP1A2.
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Echinacea may induce hepatic CYP3A4 and inhibit intestinal CYP3A4. This may increase or decrease levels of drugs metabolized by CYP3A4.
Details
Several clinical trials have shown that taking echinacea for up to one month does not significantly affect the metabolism of various CYP3A4 substrates, including midazolam, docetaxel, etravirine, lopinavir-ritonavir, and darunavir-ritonavir (13712,48618,88164,88165). However, other clinical research shows that echinacea may increase the clearance of midazolam, suggesting that echinacea might induce CYP3A4 (48618). The discrepancy is thought to be due to differing effects of echinacea on intestinal versus hepatic CYP3A4 enzymes. Echinacea appears to induce hepatic CYP3A4 but inhibit intestinal CYP3A4 (12155). In some cases, these effects might cancel each other out, but in others, drug levels may be increased or decreased depending on the level of effect at hepatic and intestinal sites. The effect of echinacea on CYP3A4 activity may differ depending on the CYP3A4 substrate (6450,11026,88162,88167).
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Theoretically, echinacea may interfere with the metabolism of darunavir; however, a small clinical study found no effect.
Details
Darunavir is metabolized by cytochrome P450 3A4 (CYP3A4) and is administered with the CYP3A4 inhibitor ritonavir to increase its plasma concentrations. Echinacea has variable effects on CYP3A4, but administration of an E. purpurea root extract (Arkocapsulas Echinacea, Arkopharma) 500 mg four times daily for 14 days did not affect darunavir/ritonavir pharmacokinetics in 15 HIV-infected patients (88163,93578).
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Theoretically, echinacea may interfere with the metabolism of docetaxel; however, a small clinical study found no effect.
Details
Docetaxel is metabolized by cytochrome P450 3A4 (CYP3A4). Echinacea has variable effects on CYP3A4, but taking E. purpurea whole plant extract (Echinaforce, A. Vogel Biopharma AG) 20 drops three times daily for 2 weeks did not alter the pharmacokinetics of docetaxel in one clinical study (88164).
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Echinacea may increase levels of etoposide.
Details
In one report, concomitant use of etoposide and echinacea was associated with more severe thrombocytopenia than the use of etoposide alone, suggesting inhibition of etoposide metabolism (20082). Etoposide is a cytochrome P450 3A4 (CYP3A4) substrate. Echinacea has variable effects on CYP3A4, but some studies have reported inhibition of the enzyme (6450,11026,12155,88162,88167).
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Theoretically, echinacea may interfere with the metabolism of etravirine; however, a small clinical study found no effect.
Details
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Echinacea has immunostimulant activity which may interfere with immunosuppressant therapy.
Details
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Theoretically, echinacea may interfere with the metabolism of lopinavir; however, a small clinical study found no effect.
Details
Lopinavir is metabolized by cytochrome P450 3A4 (CYP3A4) and is administered with the CYP3A4 inhibitor ritonavir to increase its plasma concentrations. Echinacea has variable effects on CYP3A4, but taking E. purpurea (Echinamide, Natural Factors Nutritional Products, Inc.) 500 mg three times daily for 14 days did not alter the pharmacokinetics of lopinavir/ritonavir in healthy volunteers (48618,93578).
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Theoretically, echinacea may increase the metabolism of intravenous midazolam.
Details
Echinacea induces hepatic CYP3A4 and might decrease plasma levels of midazolam by about 20%, reducing the effectiveness of intravenous midazolam (12155). Echinacea also appears to inhibit intestinal CYP3A4, which could theoretically increase the bioavailability of oral midazolam. This may cancel out the decrease in availability caused by induction of hepatic CYP3A4, such that overall plasma levels after oral administration of midazolam are not affected by echinacea.
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Echinacea seems to increase the clearance of warfarin, although the effect may not be clinically significant.
Details
Preliminary clinical research in healthy male volunteers suggests that taking echinacea increases the clearance of the active S-isomer of warfarin after a single dose of warfarin, but there was not a clinically significant effect on the INR (20083).
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Theoretically, maritime pine bark extract might increase the risk of bleeding when used with antiplatelet or anticoagulant drugs.
Details
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Theoretically, maritime pine bark extract might increase the risk of hypoglycemia when used with antidiabetes drugs.
Details
One clinical study shows that maritime pine bark extract decreases blood sugar in patients with diabetes being treated with antidiabetes agents (15522). Monitor blood glucose levels closely. Dose adjustments might be necessary.
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Theoretically, maritime pine bark extract might decrease the effectiveness of immunosuppressant therapy.
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Theoretically, concomitant use of quercetin and antidiabetes drugs might increase the risk of hypoglycemia.
Details
Clinical research suggests that a combination of quercetin, myricetin, and chlorogenic acid reduce levels of fasting glucose in patients with type 2 diabetes, including those already taking antidiabetes agents (96779). The effect of quercetin alone is unknown. |
Theoretically, taking quercetin with antihypertensive drugs might increase the risk of hypotension.
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Theoretically, concomitant use might increase the levels and adverse effects of cyclosporine.
Details
A small study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine, possibly due to inhibition of p-glycoprotein or cytochrome P450 3A4 (CYP3A4), which metabolizes cyclosporin (16434). |
Theoretically, concomitant use might increase the levels and adverse effects of CYP2C8 substrates.
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Theoretically, concomitant use might increase the levels and adverse effects of CYP2C9 substrates.
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A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac, a CYP2C9 substrate, increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5% (97931). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar), a substrate of CYP2C9 (100968). Furthermore, laboratory research shows that quercetin inhibits CYP2C9 (15549,16433). |
Theoretically, concomitant use might increase the levels and adverse effects of CYP2D6 substrates.
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Theoretically, concomitant use might alter the effects and adverse effects of CYP3A4 substrates.
Details
A small clinical study in healthy volunteers shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of a single dose of cyclosporine (Neoral, Sandimmune), a substrate of CYP3A4 (16434). Animal research also shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) and quetiapine (Seroquel), substrates of CYP3A4 (100968,104228). Other laboratory research also shows that quercetin inhibits CYP3A4 (15549,16433,16435). However, one clinical study shows that quercetin can increase the metabolism of midazolam, a substrate of CYP3A4, and decrease serum concentrations of midazolam by about 24% in some healthy individuals, suggesting possible induction of CYP3A4 (91573).
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Theoretically, concomitant use might increase the levels and adverse effects of diclofenac.
Details
A small clinical study in healthy volunteers shows that taking quercetin 500 mg twice daily for 10 days prior to taking diclofenac increases diclofenac plasma levels by 75% and prolongs the half-life by 32.5%. This is thought to be due to inhibition of CYP2C9 by quercetin (97931). |
Theoretically, concomitant use might increase the effects and adverse effects of losartan and decrease the effects of its active metabolite.
Details
Animal research shows that pretreatment with quercetin increases plasma levels and prolongs the half-life of losartan (Cozaar) while decreasing plasma levels of losartan's active metabolite. This metabolite, which is around 10-fold more potent than losartan, is the result of cytochrome P450 (CYP) 2C9- and CYP3A4-mediated transformation of losartan. Additionally, in vitro research shows that quercetin may inhibit P-glycoprotein-mediated efflux of losartan from the intestines, resulting in increased absorption of losartan (100968). These results suggest that concomitant use of quercetin and losartan might increase systemic exposure to losartan while also decreasing plasma concentrations of losartan's active and more potent metabolite. |
Theoretically, concomitant use might decrease the levels and effects of midazolam.
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A small clinical study in healthy volunteers shows that quercetin can increase the metabolism of midazolam, with a decrease in AUC of about 24% (91573). |
Theoretically, quercetin might increase the effects and adverse effects of mitoxantrone.
Details
In vitro research shows that quercetin increases the intracellular accumulation and cytotoxicity of mitoxantrone, possibly through inhibition of breast cancer resistance protein (BCRP), of which mitoxantrone is a substrate (107897). So far, this interaction has not been reported in humans.
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Theoretically, concomitant use might increase the effects and adverse effects of OAT1 substrates.
Details
In vitro research shows that quercetin is a strong non-competitive inhibitor of OAT1, with half-maximal inhibitory concentration (IC50) values less than 10 mcM (104454). So far, this interaction has not been reported in humans. |
Theoretically, concomitant use might increase the effects and adverse effects of OAT3 substrates.
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Theoretically, concomitant use might increase the effects and adverse effects of OATP substrates.
Details
In vitro evidence shows that quercetin can inhibit organic anion-transporting peptide (OATP) 1B1-mediated uptake of estrone-3-sulfate and pravastatin (91581). Furthermore, clinical research in healthy males shows that intake of quercetin along with pravastatin increases the AUC of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581). |
Theoretically, concomitant use might alter the effects and adverse effects of P-glycoprotein substrates.
Details
There is preliminary evidence that quercetin inhibits the gastrointestinal P-glycoprotein efflux pump, which might increase the bioavailability and serum levels of drugs transported by the pump (16433,16434,16435,100968,104228). A small study in healthy volunteers reported that pretreatment with quercetin increased bioavailability and plasma levels after a single dose of cyclosporine (Neoral, Sandimmune) (16434). Also, two small studies have shown that quercetin might decrease the absorption of talinolol, a substrate transported by the gastrointestinal P-glycoprotein efflux pump (91579,91580). However, in another small study, several days of quercetin treatment did not significantly affect the pharmacokinetics of saquinavir (Invirase) (16433). The reason for these discrepancies is not entirely clear (91580). Until more is known, use quercetin cautiously in combination with P-glycoprotein substrates. |
Theoretically, concomitant use might increase the effects and adverse effects of pravastatin.
Details
In vitro evidence shows that quercetin can inhibit OATP 1B1-mediated uptake of pravastatin (91581). Also, preliminary clinical research in healthy males shows that intake of quercetin along with pravastatin increases the maximum concentration of pravastatin by 24%, prolongs its half-life by 14%, and decreases its apparent clearance by 18%, suggesting that quercetin modestly inhibits the uptake of pravastatin in hepatic cells (91581).
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Theoretically, quercetin might increase the effects and adverse effects of prazosin.
Details
In vitro research shows that quercetin inhibits the transcellular efflux of prazosin, possibly through inhibition of breast cancer resistance protein (BCRP), of which prazosin is a substrate. BCRP is an ATP-binding cassette efflux transporter in the intestines, kidneys, and liver (107897). So far, this interaction has not been reported in humans.
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Theoretically, concomitant use might increase the effects and adverse effects of quetiapine.
Details
Animal research shows that pretreatment with quercetin can increase plasma levels of quetiapine and prolong its clearance, possibly due to inhibition of cytochrome P450 3A4 (CYP3A4) by quercetin. Additionally, the brain-to-plasma ratio of quetiapine concentrations increased, possibly due to inhibition of P-glycoprotein at the blood-brain barrier (104228). This interaction has not been reported in humans.
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Theoretically, concomitant use might inhibit the effects of quinolone antibiotics.
Details
In vitro, quercetin binds to the DNA gyrase site on bacteria (481), which may interfere with the activity of quinolone antibiotics.
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Theoretically, quercetin might increase the effects and adverse effects of sulfasalazine.
Details
Animal research shows that quercetin increases the maximum serum concentration (Cmax) and area under the curve (AUC) of sulfasalazine, possibly through inhibition of breast cancer resistance protein (BCRP), of which sulfasalazine is a substrate (107897). So far, this interaction has not been reported in humans.
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Theoretically, quercetin may increase the risk of bleeding if used with warfarin.
Details
Animal and in vitro studies show that quercetin might increase serum levels of warfarin (17213,109619). Quercetin and warfarin have the same human serum albumin (HSA) binding site, and in vitro research shows that quercetin has stronger affinity for the HSA binding site and can theoretically displace warfarin, causing higher serum levels of warfarin (17213). Animal research shows that taking quercetin for 2 weeks before initiating warfarin increases the maximum serum level of warfarin by 30%, the half-life by 10%, and the overall exposure by 63% when compared with control. Concomitant administration of quercetin and warfarin, without quercetin pre-treatment, also increased these measures, but to a lesser degree. Researchers theorize that inhibition of CYP3A4 by quercetin may explain these effects (109619). So far, this interaction has not been reported in humans.
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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 Ester C Plus. 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, beta-carotene is well-tolerated when used in appropriate amounts.
Most Common Adverse Effects:
Orally: Belching, orange skin (temporary).
Serious Adverse Effects (Rare):
Orally: Increased cardiovascular mortality and cancer risk in smokers and other specific patient populations.
Cardiovascular ...Orally, beta-carotene 20 to 30 mg daily seems to increase cardiovascular mortality by 12% to 26% in people who smoke (2642,3949,108641). Smokers and people with a history of asbestos exposure should not use beta-carotene supplements. In males who smoke and have had a prior myocardial infarction (MI), the risk of fatal coronary heart disease increases by as much as 43% with beta-carotene 20 mg daily (3937). These adverse effects do not seem to occur in people who eat foods high in beta-carotene content (1440,2657).
Dermatologic ...High oral doses of beta-carotene in foods or supplements can cause yellow or orange skin pigmentation called carotenoderma (11786,34572,34594,91382,108641). In clinical trials, the incidence of carotenoderma has been reported to be up to 15.8% (34626).
Gastrointestinal ...Orally, beta-carotene may cause belching (34572,34594).
Ocular/Otic ...In a case report, treatment with a high dose of beta-carotene and canthaxanthin for more than 6 years resulted in the development of glistening bright yellow crystalline deposits around the maculae. This resulted in a slight decrease in visual acuity and adaptation to the dark (34641).
Oncologic ...Smokers and people with a history of asbestos exposure should not use beta-carotene supplements. Beta-carotene in doses of 20 mg per day for 5-8 years has been associated with an increased risk of lung and prostate cancer and increased total mortality in people who smoke cigarettes (21 or more daily), and in people with a history of high-level asbestos exposure (3959,6393,11303,11786,104467,108641). These adverse effects do not seem to occur in people who eat foods high in beta-carotene content (1440,2657). There is also concern that beta-carotene might increase the risk of adverse outcomes in non-smokers. In one large-scale population study, males who took a multivitamin more than 7 times per week and who also took a separate beta-carotene supplement had a significantly increased risk of developing advanced prostate cancer (15607).
Pulmonary/Respiratory ...Clinical research shows that taking beta-carotene 20 mg daily, alone or along with vitamin E 50 mg daily, increases the risk of common colds by 21% to 25% in individuals participating in heavy exercise at leisure. However, it does not appear to affect the risk of common cold in individuals who participate in heavy activity at work (34508).
Other ...Analysis of studies in smokers and non-smokers suggests that taking beta-carotene supplements alone or in combination with other antioxidants increases the risk of mortality from all causes (15305).
General
...Orally and intravenously, calcium is well-tolerated when used appropriately.
Most Common Adverse Effects:
Orally: Belching, constipation, diarrhea, flatulence, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Case reports have raised concerns about calciphylaxis and kidney stones.
Cardiovascular
...There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI).
Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI (16118,17482,91350,107233). However, these results, particularly meta-analyses, have been criticized for excluding trials in which calcium was administered with vitamin D (94137). Many of these trials also only included postmenopausal females. Other analyses report conflicting results, and have not shown that calcium intake affects the risk of CVD, CHD, or MI (92994,93533,97308,107231). Reasons for these discrepancies are not entirely clear. It may relate to whether calcium is taken as monotherapy or in combination with vitamin D. When taken with vitamin D, which is commonly recommended, calcium supplementation does not appear to be associated with an increased risk of CVD, CHD, or MI (93533,107231). Also, the association between calcium supplementation and CVD, CHD, or MI risk may be influenced by the amount of calcium consumed as part of the diet. Supplementation with calcium may be associated with an increased risk of MI in people with dietary calcium intake above 805 mg daily, but not in those with dietary calcium intake below 805 mg daily (17482). To minimize the possible risk of CVD, CHD, or MI, advise patients not to consume more than the recommended daily intake of 1000-1200 mg and to consider total calcium intake from both dietary and supplemental sources (17484). While dietary intake of calcium is preferred over supplemental intake, advise patients who require calcium supplements to take calcium along with vitamin D, as this combination does not appear to be associated with an increased risk of MI (93533).
Rarely, calcium intake can increase the risk of calciphylaxis, which usually occurs in patients with kidney failure. Calciphylaxis is the deposition of calcium phosphate in arterioles, which causes skin ulcers and skin necrosis. In a case report, a 64-year-old female with a history of neck fracture, sepsis, and ischemic colitis presented with painful leg ulcers due to calciphylaxis. She discontinued calcium and vitamin D supplementation and was treated with sodium thiosulfate and supportive care (95816).
Gastrointestinal ...Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea (1824,1843,12950,38803). Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect (1824,1843,1844,1845,12950,38978). Calcium carbonate has been reported to cause acid rebound, but this is controversial (12935,12936).
Oncologic ...There is some concern that very high doses of calcium might increase the risk of prostate cancer. Some epidemiological evidence suggests that consuming over 2000 mg/day of dietary calcium might increase the risk for prostate cancer (4825,12949). Additional research suggests that calcium intake over 1500 mg/day might increase the risk of advanced prostate cancer and prostate cancer mortality (14132). Consumption of dairy products has also been weakly linked to a small increase in prostate cancer risk (98894). However, contradictory research suggests no association between dietary intake of calcium and overall prostate cancer risk (14131,14132,104630). More evidence is needed to determine the effect of calcium, if any, on prostate cancer risk.
Renal ...Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years (93943).
General
...Orally, echinacea is well tolerated.
Most Common Adverse Effects:
Orally: Abdominal pain, constipation, diarrhea, heartburn, nausea and vomiting, rashes, and stomach upset.
Serious Adverse Effects (Rare):
Orally: Severe allergic reactions and hepatitis have been reported.
Dermatologic ...Itching, urticaria, tingling, and allergic rashes have been reported with various echinacea preparations (8225,12355,17519,20059,20077,101592,111530,111540). In a study of children aged 2-11 years, rash occurred in about 7% of children treated with an extract of the above-ground parts of E. purpurea (EC31J2, Echinacin Saft, Madaus AG), compared with about 3% of those treated with placebo (4989,95652). There is concern that allergic reactions could be severe in some children. The Medicines and Healthcare Products Regulatory Agency in the United Kingdom (UK) recommends against the use of oral echinacea products in children under 12 years of age due to this risk of allergic reaction (18207). However, another study in children 4-12 years old shows that a specific E. purpurea product (Echinaforce Junior, A. Vogel) did not cause allergic or urticarial reactions more frequently than vitamin C (105719).
Gastrointestinal ...Gastrointestinal adverse effects include nausea and vomiting, abdominal pain, stomach upset, heartburn, diarrhea, and constipation (10802,11970,12355,13419,17519,20059,48680,105719,106626). An unpleasant taste, dry mouth, and burning, tingling or numbness of the tongue also occur (11970,12355,17519,20059,20070,20077).
Hematologic ...A 51-year-old female presented with leukopenia after taking echinacea 450 mg three times daily for 2 months, along with ginkgo biloba, multivitamins, and calcium. Her leukocyte count recovered upon stopping these supplements, but dropped again when she restarted echinacea alone about a year later. The problem resolved when echinacea was stopped permanently (48533). A 32-year-old male presented with severe thrombotic thrombocytopenic purpura (TTP) about 2 weeks after using an extract of E. pallida to treat a cold. He required admission to an intensive care unit and extensive plasmapheresis. The authors speculate that immunostimulant effects of echinacea induced or exacerbated the TTP (48572).
Hepatic
...Although uncommon, cases of echinacea-induced hepatitis have been reported.
One case report describes acute cholestatic autoimmune hepatitis in a 45-year-old male who had been taking an echinacea root extract 1500 mg daily for about 2 weeks. He presented with significantly elevated liver function tests (LFTs), elevated immunoglobulin G (IgG) levels, and a positive test for anti-smooth muscle antibodies, indicating an autoimmune process. Elevated LFTs and IgG levels returned to normal within one month of stopping echinacea (17518). Another case report describes acute cholestatic hepatitis in a 44-year-old male who had taken echinacea root tablets 600 mg daily for 5 days to treat flu-like symptoms. He presented with elevated LFTs, prothrombin time, and international normalized ratio (INR). His condition gradually improved after stopping echinacea, and his LFTs normalized within 3 months (91528).
Seven cases of hepatitis associated with echinacea use were reported to the Australian Adverse Drug Reactions Advisory Committee between 1979 and 2000, but specific details are lacking (8225).
One case report describes acute liver failure in a 2 year-old child who had been given about 100 mg of echinacea daily for 2 weeks. The patient presented with jaundice, diarrhea, lethargy, anorexia, and significantly elevated LFTs. A liver biopsy showed hepatocyte swelling, spotty necrosis, and inflammatory infiltrate with eosinophils. A full recovery was made over a 2-week period (88166).
Immunologic
...Allergic reactions, including urticaria, runny nose, dyspnea, bronchospasm, acute asthma, angioedema, and anaphylaxis, have been reported with various echinacea preparations (638,1358,8225).
Atopic individuals and those sensitive to other members of the Asteraceae family (ragweed, chrysanthemums, marigolds, daisies) seem to be at higher risk for these reactions (1358,8225).
A case report describes a 36-year-old female who presented with muscle weakness, electrolyte abnormalities, renal tubular acidosis, fatigue, and dry mouth and eyes after taking echinacea, kava, and St. John's Wort for 2 weeks., She also had a positive antinuclear antibody (ANA) test, with elevated anti-dsDNA antibodies SSA and SSB. Sjogren syndrome was diagnosed; the authors hypothesize that it may have been triggered by the immunostimulant effects of echinacea (10319). A 55-year-old male with a history of pemphigus vulgaris in remission for about a year experienced a flare of the disease after taking an echinacea supplement for one week. After stopping echinacea, medical treatment resulted in partial control of the disease (12171). Another case report describes a 58-year-old male who presented with marked eosinophilia and elevated immunoglobulin E (IgE) levels while taking an echinacea supplement. He required prednisone therapy until he stopped taking echinacea 3 years later, at which time his eosinophils and IgE normalized (48623). A 41-year-old male experienced four episodes of erythema nodosum, each occurring after he had taken echinacea for early symptoms of influenza. After stopping echinacea, he had no further exacerbations of erythema nodosum, suggesting that it had been triggered by the immunostimulant effects of echinacea (7057).
Musculoskeletal ...Reports of arthralgia and myalgia have been associated with echinacea (13418).
Neurologic/CNS ...Headache has been reported in people taking various echinacea preparations orally (3282,11970,17519,20059,20064). Dizziness has also been reported (3282,8225,11970). In one study using an alcoholic extract of the above-ground parts of E. purpurea (EC31J0, Echinacin, Madaus AG), somnolence and a tendency to aggressiveness were reported (3282).
General
...Orally and topically, maritime pine bark extract seems to be well tolerated.
Most Common Adverse Effects:
Orally: Gastrointestinal complaints, dizziness, and vertigo.
Cardiovascular ...A single case of chest pain has been reported for a patient treated with a standardized extract of maritime pine bark (Pycnogenol, Horphag Research). However, the patient had a history of myocardial infarction (50905). Another patient taking the same maritime pine bark extract experienced acute decompensation of heart failure. The patient previously has stable coronary artery disease (50929). It is not clear if either of these adverse effects were directly related to maritime pine bark extract.
Gastrointestinal ...Orally, a standardized extract of maritime pine bark (Pycnogenol, Horphag Research) may cause gastrointestinal problems (15521,15522,17300,50891,50942). Also, mouth ulcer and bad breath have been reported in a single trial (15521).
Neurologic/CNS ...Orally, a standardized extract of maritime pine bark (Pycnogenol, Horphag Research) may cause dizziness and severe vertigo (15521,15522,17300,50904,50933). Also, headache has been reported in a single trial (15521).
General ...Orally and intravenously, quercetin seems to be well tolerated in appropriate doses. Topically, no adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.
Gastrointestinal ...Intravenous administration of quercetin is associated with nausea and vomiting (9564).
Neurologic/CNS ...Orally, quercetin may cause headache and tingling of the extremities (481,111500). Intravenously, quercetin may cause pain at the injection site. Injection pain can be minimized by premedicating patients with 10 mg of morphine and administering amounts greater than 945 mg/m2 over 5 minutes (9564). In addition, intravenous administration of quercetin is associated with flushing and sweating (9564).
Pulmonary/Respiratory ...Intravenous administration of quercetin at doses as high as 2000 mg/m2 is associated with dyspnea that may persist for up to 5 minutes (9564).
Renal ...Intravenously, nephrotoxicity has been reported with quercetin in amounts greater than 945 mg/m2 (9563,9564,70304).
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).
