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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
Patients should avoid vitamin C products if they are sensitive or allergic to any of their ingredients.
Side Effects and Warnings
Vitamin C is generally regarded as safe in amounts obtained from foods. Vitamin C supplements are also generally regarded as safe in most individuals in recommended amounts, although there are rarely reported side effects 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. Large doses may precipitate hemolysis (red blood cell destruction) in patients with glucose 6-phosphate dehydrogenase deficiency. High doses of vitamin C should be avoided in people with conditions aggravated by acid loading, such as cirrhosis, gout, renal tubular acidosis, or paroxysmal nocturnal hemoglobinuria. Parenteral (injected) vitamin C may cause dizziness, faintness, injection site discomfort, and in high doses may lead to renal insufficiency (kidney function problems). In cases of toxicity due to massive ingestions of vitamin C, forced fluids and diuresis may be beneficial.
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.
Pregnancy and Breastfeeding
Vitamin C intake from food is generally considered safe during pregnancy. However, it is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial. There are rare reports of scurvy due to tolerance/resistance in infants born to mothers taking extra vitamin C throughout their 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 the development of childhood allergies. It is not clear if vitamin C supplementation in amounts exceeding Dietary Reference Intake recommendations is safe or beneficial.
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Portions of this document last updated:Sept. 1, 2009
THE NATURAL STANDARD RESEARCH COLLABORATION
(www.naturalstandard.com)
