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Vitamin C (ascorbic acid)
DRUGS AND SUPPLEMENTS

Vitamin C (ascorbic acid)

March 22, 2017

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Vitamin C (ascorbic acid)

Natural Standard Bottom Line Monograph, Copyright © 2013 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.

Related Terms

  • Acide ascorbique (French), acide cévitamique (French), acide iso-ascorbique (French), acide L-ascorbique (French), ácido ascórbico (Spanish), antiscorbutic vitamin, ascorbate, ascorbate de calcium, ascorbate de sodium, ascorbic acid (AA), ascorbyl palmitate, calcium ascorbate, cevitamic acid, iso-ascorbic acid, L-ascorbic acid, magnesium ascorbate, palmitate d'ascorbyl (French), selenium ascorbate, sodium ascorbate, vitamina C (Spanish), vitamine antiscorbutique (French), vitamine C (French).

Background

  • Vitamin C (ascorbic acid) is a water-soluble vitamin, which is needed by the body to form collagen in bones, cartilage, muscle, and blood vessels, and which aids in the absorption of iron. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges.

  • Severe deficiency of vitamin C causes scurvy. Although rare, scurvy includes potentially severe consequences and can cause sudden death. Patients with scurvy are treated with vitamin C and should be under medical supervision.

  • Many uses for vitamin C have been proposed, but few have been found to be beneficial in scientific studies. In particular, research on asthma, cancer, and diabetes remains inconclusive, and no benefits have been found for the prevention of cataracts or heart disease.

  • The use of vitamin C in the prevention or treatment of the common cold and respiratory infections remains controversial, with research ongoing. For cold prevention, more than 30 clinical trials including over 10,000 participants have examined the effects of taking daily vitamin C. Overall, no significant reduction in the risk of developing colds has been observed. In people who developed colds while taking vitamin C, no difference in the severity of symptoms has been seen overall, although a small, significant reduction in the duration of colds has been reported (approximately 10% in adults and 15% in children). Notably, some studies of people living in extreme circumstances, including soldiers in subarctic exercises, skiers, and marathon runners, have found a significant reduction in the risk of developing a cold, by approximately 50%. This area merits additional research and may be of particular interest to elite athletes or military personnel. For cold treatment, numerous studies have examined the effects of starting vitamin C after the onset of cold symptoms. So far, significant benefits have not been observed.

Scientific Evidence

Uses

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Grade*

Vitamin C deficiency (scurvy)

Scurvy is caused by a dietary deficiency of vitamin C. Although scurvy is uncommon, it may occur in malnourished individuals, those with increased vitamin C requirements (such as pregnant or breastfeeding women), or infants whose only source of nourishment is breast milk. Vitamin C administered by mouth or injection is effective for curing scurvy. If vitamin C is not available, orange juice can be used for infantile scurvy. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision.

A

Common cold prevention (extreme environments)

Scientific studies generally suggest that vitamin C does not prevent the onset of cold symptoms. However, in a subset of studies of people living in extreme climates or under extraordinary conditions, including soldiers in subarctic exercises, skiers, and marathon runners, vitamin C significantly reduced the risk of developing colds, by approximately 50%. This area merits more research and may be of particular interest to elite athletes or military personnel.

B

Iron absorption enhancement

Based on scientific research, vitamin C appears to improve oral absorption of iron. Concurrent vitamin C may aid in the absorption of iron dietary supplements.

B

Urinary tract infection (during pregnancy)

Vitamin C may decrease the risk of developing urinary tract infections during pregnancy. Further research is needed to confirm this finding.

B

Age-related macular degeneration (AMD)

There is a lack of evidence showing the beneficial effects of vitamin C alone in the treatment of AMD. Further research is needed in this area.

C

Alzheimer's disease

There is limited research on the effects of vitamin C alone on the progression of Alzheimer's disease. Further research is needed before a conclusion can be made.

C

Anemia

Vitamin C may enhance the absorption of dietary iron, but additional research is needed before a conclusion can be made.

C

Arthritis (osteoarthritis and rheumatoid arthritis)

Consumption of vitamin C may reduce the risk of cartilage loss and disease progression in individuals with osteoarthritis. However, more well-designed clinical trials are needed to determine if vitamin C is beneficial for osteoarthritis or rheumatoid arthritis.

C

Asthma

It has been suggested that low levels of vitamin C (or other antioxidants) may increase the risk of developing asthma. The use of vitamin C for the treatment of asthma (particularly exercise-induced asthma) has been studied since the 1980s, although the evidence in this area remains inconclusive. More research is needed before a clear conclusion can be drawn.

C

Autism

Ascorbic acid may decrease the severity of symptoms in children with autism. More trials are needed before a conclusion can be made.

C

Bleeding stomach ulcers caused by aspirin

Early evidence suggests that vitamin C may help aspirin-induced gastric damage. More research is needed before a clear conclusion can be drawn.

C

Breast cancer (prevention)

Some studies have examined a link between the consumption of fruits and vegetables and the prevention of breast cancer. However, the exact role of vitamin C is unclear. Additional studies are needed.

C

Burns

Ascorbic acid administration to patients with severe burns significantly reduced resuscitation fluid volume requirements, body weight gain, and wound edema. Additional studies are needed before a conclusion can be made.

C

Cancer prevention

Dietary intake of fruits and vegetables high in vitamin C has been associated with a reduced risk of various types of cancer in population studies (particularly cancers of the mouth, esophagus, stomach, colon, or lung). However, it is not clear that the benefit came specifically from the vitamin C in these foods, and vitamin C supplements have not been found to be associated with this protective effect. Experts have recommended increasing dietary consumption of fruits and vegetables high in vitamin C, such as asparagus; berries; broccoli; cabbage; melon (cantaloupe; honeydew; watermelon); cauliflower; citrus fruits (lemons; oranges); fortified breads, grains, and cereal; kale; kiwi; potatoes; spinach; and tomatoes.

C

Cancer treatment

Vitamin C has a long history of use as an adjunct in cancer therapy, and although there has not been any definite evidence of a benefit from injected or oral vitamin C, there is evidence that there is benefit in some cases. More well-designed studies are needed before a firm recommendation can be made.

C

Chemotherapy (adjunct)

Vitamin C did not demonstrate a significant advantage over placebo as an adjunct to chemotherapy, as measured by an increase in survival or by tumor response. Additional studies are needed in this area.

C

Chronic diseases (mortality prevention)

Vitamin C in high doses may have beneficial effects on acute inflammation and blood vessel functioning. However, the exact role of vitamin C in chronic diseases is unclear, and more high-quality human studies are needed.

C

Chronic venous insufficiency

The role of vitamin C alone in chronic venous insufficiency cannot be determined with the available evidence. Additional studies are needed.

C

Colorectal cancer

Vitamin C has not been shown to decrease total cancer incidence or cancer mortality. Additional studies are needed before a conclusion can be made.

C

Complex regional pain syndrome

Clinical research suggests that vitamin C may prevent complex regional pain syndrome among elderly female patients with wrist fracture. Additional studies suggest that vitamin C may help to reduce pain associated with this syndrome.

C

Cystic fibrosis

The role of vitamin C in patients with cystic fibrosis is currently unclear. Additional research is needed in this area.

C

Diabetic retinopathy

A review included four studies of the relationship between vitamin C alone and diabetic neuropathy. However, there was a lack of studies that administered vitamin C to determine if it had any effects on symptoms associated with this condition. Well-designed trials are needed.

C

Endometrial cancer (prevention)

Based on studies included in a review, the effects of vitamin C supplementation on the prevention of endometrial cancer are mixed. Further research is needed before a conclusion can be made.

C

Erythropoietic protoporphyria (EPP)

Erythropoietic protoporphyria (EPP) is a rare inherited disease characterized by dermal photosensitivity due to the accumulation of photosensitizer protoporphyrin IX. More research is needed to determine if vitamin C is beneficial for this condition.

C

Exercise recovery

Vitamin C may prevent endurance exercise-induced oxidative damage to fat and muscle tissue in healthy people. More research is needed before a conclusion can be made.

C

Gallbladder disease

Vitamin C supplementation and increased vitamin C serum levels may decrease the risk of developing gallbladder disease in women. Well-designed trials are needed.

C

Heart conditions (heart protection during chemotherapy)

There is currently a lack of studies that have examined the effects of vitamin C alone for heart-protective effects in patients receiving chemotherapy. Additional studies are needed.

C

Helicobacter pylori infection

Adding vitamin C to triple therapy with omeprazole, amoxicillin, and clarithromycin for Helicobacter pylori gastric ulcer treatment may allow the dose of clarithromycin to be lower. Further research is needed to confirm this result.

C

High blood pressure

Dietary restriction of vitamin C may be associated with increases in both diastolic and systolic blood pressure. Vitamin C supplementation has been shown to decrease systolic and diastolic blood pressure. Further research is needed in this area.

C

High cholesterol

According to studies in humans, vitamin C supplementation may have beneficial effects in patients with high cholesterol. More research is needed in this area.

C

HIV (transmission)

According to secondary sources, supplementation of mothers with HIV disease with vitamin B, vitamin C, and vitamin E may reduce child mortality and HIV transmission through breast milk. Well-designed studies are needed.

C

Ischemic heart disease

Due to its antioxidant properties, vitamin C has been used in patients with ischemic heart disease. Early data suggest that vitamin C may have a benefit on blood flow in the heart, but more research is needed to confirm this finding.

C

Kidney disease (contrast-induced nephropathy prevention)

Vitamin C before and after coronary angiography may reduce the risk of developing contrast-mediated kidney disease. According to a trial included in a systematic review, a significant reduction in contrast-mediated kidney disease was observed. Additional trials are needed before a conclusion can be made.

C

Lead toxicity

Consuming vitamin C from dietary sources may lower blood concentrations of lead. Additional studies are needed.

C

Liver disease

Administration of vitamin C in individuals with cirrhosis may have some benefit. However, in patients with chronic hepatitis C, vitamin C was not effective. Additional studies are needed before a conclusion can be made.

C

Lung disease

An oxidant-antioxidant balance may play a role in maintaining proper lung function. Limited studies have examined the role of vitamin C alone for lung diseases. Additional well-designed trials are needed before a conclusion can be made.

C

Metabolic abnormalities

Alkaptonuria is a disorder characterized by the absence of the enzyme homogentisic acid oxidase, which causes homogentisic acid to collect in the blood and urine. Limited research reports that daily high-dose vitamin C may provide relief of symptoms and slow progression of complications of this disorder. More research is merited in this area. Oral or intramuscular vitamin C may improve tyrosinemia (genetic tyrosine metabolism disorder resulting in liver, kidney, and brain disorders) in premature infants on high-protein diets. Well-designed trials are needed in this area before a conclusion can be made.

C

Nitrate tolerance

Oral vitamin C may prevent the development of nitrate tolerance in patients taking sublingual (under the tongue) nitroglycerin. Furthermore, short-term vitamin C may prevent attenuation of tolerance to the blood vessel widening effects of nitrate. Well-designed trials are needed in this area before a conclusion can be made.

C

Nutritional support (premature infants)

Benefits or harmful effects of ascorbic acid supplementation throughout the first 28 days of life were not found in one study. Additional studies are needed before a conclusion can be made.

C

Parkinson's disease

Intake of vitamin E, vitamin C, and carotenoids may not be beneficial for symptoms associated with Parkinson's disease. The effects of vitamin C alone cannot be determined from these studies. More studies are needed.

C

Physical work capacity

Population-based research suggests that higher dietary intake of vitamin C may be associated with improved physical performance and muscle strength in the elderly. Well-designed trials are needed before a conclusion can be made.

C

Plaque/ calculus on teeth

In early studies, reduced amounts of calculus, visible plaque, and bleeding gum sites were observed after the use of vitamin C chewing gum. Further research is needed to confirm these results.

C

Pneumonia (prevention)

Vitamin C may play a role in the prevention of pneumonia. However, further research is needed to confirm available study results.

C

Pregnancy

There is not enough evidence to conclude if vitamin C supplementation alone or combined with other supplements is beneficial during pregnancy. Preterm birth may increase with vitamin C supplementation. Some study results show that daily supplementation can effectively lessen the incidence of premature rupture of chorioamniotic membranes (PROM). A gynecologist and pharmacist should be consulted before taking any herbs or supplements during pregnancy.

C

Pressure ulcers

Vitamin C supplementation may be effective for reducing pressure sore areas. However, the results of the available studies in humans are conflicting.

C

Prostate cancer

Vitamin C has been used in prostate cancer treatment. The current evidence is mixed, and it is unclear whether vitamin C is beneficial for individuals with prostate cancer.

C

Proteinuria (albuminuria)

Vitamin C plus vitamin E may reduce the excretion of albumin in patients with type 2 diabetes. Further research is needed in this area.

C

Skin aging (wrinkles)

Topical preparations containing 3-10% vitamin C may improve the appearance of wrinkled skin, as evidenced by improved fine and coarse wrinkling, yellowing and sallowness, roughness, and skin tone. Well-designed trials are needed in this area before a conclusion can be made.

C

Skin conditions (erythema)

A water-based formulation of vitamin C used on the skin may decrease skin irritation following laser treatments for scar and wrinkle removal. Well-designed studies are needed.

C

Skin damage caused by the sun (UVA-induced)

Vitamin C and vitamin E applied to the skin may not prevent UVA-induced skin damage (suntan). Further research is needed to confirm this finding.

C

Skin pigmentation disorders (perifollicular pigmentation)

Limited evidence suggests a role for vitamin C in perifollicular pigmentation, which is increased color pigment near the hair follicle. Additional studies are needed before a conclusion can be made.

C

Stroke prevention

There are variable results of studies that have measured the association of vitamin C intake and the risk of stroke. Some studies have reported no benefits, while others report that daily low-dose vitamin C may reduce the risk of death from stroke. More research is merited in this area. Individuals at risk of having a stroke should speak with their healthcare providers about the role of vitamin C supplements in stroke prevention.

C

Tetanus

Tetanus is a severe infection that may be prevented by vaccination. In developing countries, vaccination coverage is not always high, and in developed countries, cases may still occur, particularly in elderly people, owing to their reduced immune system functioning. It has been estimated that there are about one million cases of tetanus per year globally. Vitamin C may prevent mortality from tetanus infection. However more high-quality human studies are needed.

C

Type 2 diabetes

The effects of vitamin C in patients with diabetes are mixed. Additional studies are needed.

C

Vaginitis

Preliminary human research shows that vitamin C vaginal tablets given once daily may help patients suffering from nonspecific vaginitis. Further research is needed to confirm this finding.

C

Cataracts (prevention/progression)

Although early population research suggested a reduction in cataract formation among individuals taking vitamin C for at least 10 years, subsequent research found no reduction in the seven-year risk of age-related cataract formation or progression with the use of daily vitamin C.

D

Common cold prevention (general)

More than 30 clinical trials including more than 10,000 participants have examined the effects of taking daily vitamin C on cold prevention. Overall, a significant reduction in the risk of developing colds has not been observed. In people who developed colds while taking vitamin C, no difference in the severity of symptoms has been seen overall, although a small, significant reduction in the duration of colds has been reported (approximately 10% in adults and 15% in children). Laboratory experiments in which volunteers were infected with respiratory viruses while taking vitamin C have yielded conflicting results, but overall, they reported small or no significant differences in symptom severity following infection. Notably, some studies in people living in extreme circumstances, including soldiers in subarctic exercises, skiers, and marathon runners, have reported a significant reduction in the risk of developing a cold, by approximately 50%. This area merits additional research and may be of particular interest to elite athletes or military personnel.

D

Common cold treatment

Numerous studies have examined the effects of starting vitamin C after the onset of cold symptoms. Overall, no significant benefits have been observed. Initial evidence from one study reported possible benefits with high doses of vitamin C taken at the onset of symptoms, but without additional evidence, this remains indeterminate. At this time, the scientific evidence does not support this use of vitamin C.

D

Heart disease prevention

Vitamin C does not appear to lower cholesterol levels or reduce the risk of heart attacks. Its effects on cholesterol plaques in heart arteries (atherosclerosis) remain unclear, and some studies have suggested possible beneficial vasodilation (artery-opening) properties. Based on the current scientific evidence, vitamin C is generally not recommended for this use. People at risk of heart attacks should speak with their healthcare providers to consider preventive measures such as aspirin.

D

*Key to grades:A: Strong scientific evidence for this use; B: Good scientific evidence for this use; C: Unclear scientific evidence for this use; D: Fair scientific evidence against this use (it may not work); F: Strong scientific evidence against this use (it likely does not work).

Tradition/Theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

  • Acne, aging, anti-inflammatory, atherosclerosis (hardening of the arteries), attention-deficit hyperactivity disorder, bedsores, blood disorders (idiopathic methemoglobinemia, hematuria), blood vessel disorders (capillary fragility), bronchitis, bursitis, cervical dysplasia, chronic fatigue syndrome (CFS), cognitive function, connective tissue disorders (collagen disorders), constipation, cystitis, dementia, dental conditions (discoloration of tooth enamel, dental cavities, pyorrhea), depression, dermatitis, detoxification (histamine), drug withdrawal, dysentery, endurance, eye disorders (glaucoma), fatigue, fractures, furunculosis (recurrent boils), gastric ulcer, gout, gum disease, hay fever, hemorrhage (retinal), idiopathic thrombocytopenic purpura, immune disorders (Chediak-Higashi syndrome, immune stimulation), infertility, influenza (swine), jellyfish stings, Lyme disease, melasma, menorrhagia (heavy menstrual bleeding), muscle soreness, pain (back pain, fractures), prostatitis, sickle cell disease, stomach ulcers, stress, thrombosis (vascular), toxicity (levodopa, interferon, aspirin, arsenic, mercury elimination), tuberculosis, urine acidification, viral infections, wound healing.

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

Adults (over 18 years old)

  • The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for men more than 18 years old is 90 milligrams daily; for women more than 18 years old, it is 75 milligrams daily; for pregnant women more than 18 years old, it is 85 milligrams daily; and for breastfeeding women more than 18 years old, it is 120 milligrams daily. Recently, some experts have questioned whether the recommended daily intake should be raised. Others have recommended higher intake in some individuals, such as smokers, in whom an additional 35 milligrams daily has been recommended by some.

  • The upper limit of intake (UL) should not exceed 2,000 milligrams daily in men or women more than 18 years old (including pregnant or breastfeeding women).

  • Vitamin C administered by mouth or injection is effective for curing scurvy. In adults, 100-250 milligrams by mouth four times daily for one week is generally sufficient to improve symptoms and replenish body vitamin C stores. Some experts have recommended 1-2 grams daily for two days, followed by 500 milligrams daily for one week. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision. For asymptomatic vitamin C deficiency, lower daily doses may be used.

  • For treating the common cold, 1-3 grams daily has been used. For preventing the common cold in people under physical stress, 600-1,000 milligrams of vitamin C daily has been used. During acute stress, one gram of vitamin C three times daily, as a sustained-release preparation, has been used for up to 14 days.

  • For preventing contrast-mediated nephropathy, three grams of vitamin C is given before coronary angiography and then two grams is given after the procedure, in the evening and again the following morning. For chronic hemodialysis in adults, 100-200 milligrams daily has been used.

  • For preventing nitrate tolerance, 3-6 grams of vitamin C has been used daily.

  • For treatment of premalignant gastric lesions, one gram of vitamin C has been used twice daily.

  • For infertility associated with luteal phase defect, 750 milligrams of vitamin C has been used daily.

  • For preventing complex regional pain syndrome in patients with wrist fractures, 500 milligrams of vitamin C daily for 50 days has been used.

  • For preventing gout, 500-1,500 milligrams of vitamin C daily from food and/or supplements has been used.

  • For high blood pressure, the median vitamin C dose and study duration has been 500 milligrams daily and six weeks, respectively.

  • Most topical preparations used for aged or wrinkled skin are applied daily and may contain 5-10% vitamin C.

Children (under 18 years old)

  • The recommended daily intake by the U.S. Food and Nutrition Board of the Institute of Medicine for infants 0-12 months old is human milk content (older recommendations specified 30-35 milligrams); for children 1-3 years old, it is 15 milligrams; for children 4-8 years old, it is 25 milligrams; for children 9-13 years old, it is 45 milligrams; and for adolescents 14-18 years old, it is 75 milligrams for boys and 65 milligrams for girls. The tolerable upper intake levels (UL) for vitamin C are 400 milligrams daily for children 1-3 years old; 650 milligrams daily for children 4-8 years old; 1,200 milligrams daily for children 9-13 years old; and 1,800 milligrams daily for adolescents and pregnant and lactating women 14-18 years old.

  • For scurvy or vitamin C deficiency in children, 100-300 milligrams of vitamin C daily by mouth in divided doses for two weeks has been used. Older or larger children may require doses closer to adult recommendations. If vitamin C is not available, orange juice may be used for infantile scurvy. Symptoms should begin to improve within 24-48 hours, with resolution within seven days. Treatment should be under strict medical supervision.

  • For tyrosinemia in premature infants on high-protein diets, 100 milligrams of vitamin C has been used.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Allergies

  • Avoid if sensitive or allergic to any ingredients present in Vitamin C products.

Side Effects and Warnings

  • Vitamin C is generally regarded as safe in amounts normally obtained from foods. Vitamin C supplements are also generally regarded as safe in most individuals in recommended amounts, although side effects are rarely reported, including nausea, vomiting, heartburn, abdominal cramps, and headache. Dental erosion may occur from chronically chewing vitamin C tablets.

  • High doses of vitamin C have been associated with multiple adverse effects. These include kidney stones, severe diarrhea, nausea, and gastritis. Rarely, flushing, faintness, dizziness, and fatigue have been noted. In cases of toxicity due to massive ingestions of vitamin C, forced fluids, and diuresis may be beneficial. In postmenopausal women with diabetes, supplemental vitamin C in doses greater than 300 milligrams daily has been associated with increased risk of heart-related death.

  • Healthy adults who take chronic large doses of vitamin C may experience low blood levels of vitamin C when they stop taking the high doses and resume normal intake. To avoid this potential complication, people who are taking high doses who wish to reduce their intake should do so gradually rather than acutely. There are rare reports of scurvy due to tolerance or resistance following cessation after long-term high-dose use, such as in infants born to mothers taking extra vitamin C throughout their pregnancy.

  • Vitamin C in high doses appears to interfere with the blood-thinning effects of anticoagulants such as warfarin by lowering prothrombin time (PT). Caution is advised in patients with bleeding disorders or those taking drugs that affect bleeding. Dosing adjustments may be necessary.

  • Vitamin C may affect blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

  • Use cautiously in patients with cancer, glucose-6-phosphate dehydrogenase deficiency, anemia and related conditions, kidney stones, or sickle cell disease, or after angioplasty. Use cautiously in patients taking antibiotics, anticancer agents, HIV medications, barbiturates, estrogens, fluphenazine, or iron supplements. Use parenteral (injected) vitamin C cautiously, as it may cause dizziness, faintness, or injection site discomfort, and in high doses, it may lead to renal insufficiency (kidney function problems).

  • Avoid in patients with known allergies or hypersensitivities to any ingredients in Vitamin C products. Avoid high doses of vitamin C in people with conditions aggravated by acid loading, such as cirrhosis, gout, renal tubular acidosis, or paroxysmal nocturnal hemoglobinuria. Avoid high doses of vitamin C in patients with kidney failure or in those taking agents that may damage the kidneys, due to an increased risk of kidney failure.

Pregnancy and Breastfeeding

  • Vitamin C intake from food is generally considered safe during pregnancy. It is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial during pregnancy. There are rare reports of scurvy due to tolerance or resistance in infants born to mothers taking extra vitamin C throughout the pregnancy. The data are too few to say if vitamin C supplementation alone or combined with other supplements is beneficial during pregnancy. Preterm birth may increase with vitamin C supplementation.

  • Vitamin C is present in breast milk. Vitamin C intake from food is generally considered safe in breastfeeding mothers. Limited research suggests that vitamin C in breast milk may reduce the risk of developing childhood allergies. It is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial during breastfeeding.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.

Interactions with Drugs

  • Vitamin C in high doses appears to interfere with the blood-thinning effects of anticoagulants such as warfarin by lowering prothrombin time (PT).

  • Vitamin C may affect blood sugar levels. Caution is advised when using medications that may also affect blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

  • Vitamin C may affect blood pressure. Caution is advised in patients taking agents that affect blood pressure.

  • Vitamin C may also interact with acetaminophen, acidifying agents, antacids, antibiotics, anticancer drugs, aspirin, barbiturates, cholesterol-lowering agents, diuretics, estrogens, fluphenazine, HIV medications, indinavir, kidney-damaging agents, levodopa, nicardipine, nicotine-containing products (such as cigarettes, cigars, chewing tobacco, or nicotine patches), progesterones, proton pump inhibitors (PPIs), and salicylates.

Interactions with Herbs and Dietary Supplements

  • Vitamin C in high doses appears to interfere with the blood-thinning effects of anticoagulants by lowering prothrombin time (PT).

  • Vitamin C may affect blood sugar levels. Caution is advised when using herbs or supplements that may also affect blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

  • Vitamin C may affect blood pressure. Caution is advised in patients taking herbs or supplements that affect blood pressure.

  • When taken together, vitamin C may increase the absorption of iron in the gastrointestinal tract, although this effect appears to be variable and may not be clinically significant.

  • Large doses of vitamin C may interfere with the absorption and metabolism of vitamin B12.

  • Vitamin C may also interact with acerola, antacids, antibacterials, anticancer agents, antioxidants, antivirals, Cherokee rosehip, cholesterol-lowering agents, chromium, copper, diuretics, grape seed extract, grapefruit, hormonal agents, kidney-damaging agents, lutein, niacin, tobacco, sedatives, urine acidifying agents, and vitamin E.

Author Information

  • This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Bjelakovic G, Gluud LL, Nikolova D, et al. Meta-analysis: antioxidant supplements for liver diseases - the Cochrane Hepato-Biliary Group. Aliment Pharmacol Ther. 2010 Aug;32(3):356-67. View Abstract

  2. Douglas RM, Hemilä H, Chalker E, et al. Vitamin C for preventing and treating the common cold. Cochrane Database Syst Rev 2007 Jul 18;(3):CD000980. View Abstract

  3. Duconge J, Miranda-Massari JR, et al. Vitamin C pharmacokinetics after continuous infusion in a patient with prostate cancer. Ann Pharmacother 2007 Jun;41(6):1082-3. View Abstract

  4. Ehrlich M, Rao J, Pabby A, et al. Improvement in the appearance of wrinkles with topical transforming growth factor beta(1) and l-ascorbic acid. Dermatol Surg 2006 May;32(5):618-25. View Abstract

  5. Hemilä H, Louhiala P. Vitamin C for preventing and treating pneumonia. Cochrane Database Syst Rev 2007 Jan 24;(1):CD005532. View Abstract

  6. Inui S, Itami S. Perifollicular pigmentation is the first target for topical vitamin C derivative ascorbyl 2-phosphate 6-palmitate (APPS): randomized, single-blinded,placebo-controlled study. J Dermatol 2007 Mar;34(3):221-3. View Abstract

  7. Jiang L, Yang KH, Tian JH, et al. Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials. Nutr Cancer. 2010 Aug;62(6):719-27. View Abstract

  8. Konturek PC, Kania J, Hahn EG, et al. Ascorbic acid attenuates aspirin-induced gastric damage: role of inducible nitric oxide synthase. J Physiol Pharmacol 2006 Nov;57 Suppl 5:125-36. View Abstract

  9. Lin J, Cook NR, Albert C, et al. Vitamins C and E and beta carotene supplementation and cancer risk: a randomized controlled trial. J Natl Cancer Inst 2009 Jan 7;101(1):14-23. View Abstract

  10. McNulty PH, Robertson BJ, Tulli MA, et al. Effect of hyperoxia and vitamin C on coronary blood flow in patients with ischemic heart disease. J Appl Physiol 2007 May;102(5):2040-5. View Abstract

  11. Muran PJ. Mercury elimination with oral DMPS, DMSA, vitamin C, and glutathione: an observational clinical review. Altern Ther Health Med 2006 May-Jun;12(3):70-5. View Abstract

  12. Nankivell BJ, Murali KM. Images in clinical medicine. Renal failure from vitamin C after transplantation.N Engl J Med 2008 Jan 24;358(4):e4. View Abstract

  13. Ochoa-Brust GJ, Fernández AR, Villanueva-Ruiz GJ, et al. Daily intake of 100 mg ascorbic acid as urinary tract infection prophylactic agent during pregnancy. Acta Obstet Gynecol Scand 2007;86(7):783-7. View Abstract

  14. Puvabanditsin P, Vongtongsri R. Efficacy of topical vitamin C derivative (VC-PMG) and topical vitamin E in prevention and treatment of UVA suntan skin. J Med Assoc Thai 2006 Sep;89 Suppl 3:S65-8. View Abstract

  15. Zollinger PE, Tuinebreijer WE, Breederveld RS, et al. Can vitamin C prevent complex regional pain syndrome in patients with wrist fractures? A randomized, controlled, multicenter dose-response study. J Bone Joint Surg Am 2007 Jul;89(7):1424-31. View Abstract

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Updated:  

March 22, 2017