Vitamin poisoning

Overview
Vitamin poisoning, or hypervitaminosis, refers to a condition of high storage levels of vitamins, which can lead to toxic symptoms. The medical names of the different conditions are derived from the vitamin involved: an excess of vitamin A, for example, is called "hypervitaminosis A".

High dosage vitamin A; high dosage, slow release vitamin B3; and very high dosage vitamin B6 alone (i.e. without vitamin B complex) are sometimes associated with vitamin side effects that usually rapidly cease with supplement reduction or cessation. Conversely, certain vitamins do not produce toxicity in excess levels. Vitamin C has been used in dosages over 100,000 mg for serious illness — over 1000 times the daily recommended intake — without ill effects. However, Vitamin C does have a pronounced laxative effect, typically when intake of vitamin C is in the range of 5-20 grams per day for a person in normal "good health".

High doses of mineral supplements can also lead to side effects and toxicity. Mineral-supplement poisoning does occur occasionally due to excessive and unusual intake of iron-containing supplements, including some multivitamins, but is not common.

The Dietary Reference Intake recommendations from the United States Department of Agriculture define a "tolerable upper intake level" for most vitamins.

Comparative safety statistics
Death by vitamin poisoning appears to be quite rare in the US, typically none in a given year. However before 1998, several deaths per year were typically associated with pharmaceutical iron-containing supplements, especially brightly-colored, sugar-coated, high-potency iron supplements, and most deaths were children. Unit packaging restrictions on supplements with more than 30 mg iron have since reduced deaths to 0 or 1 per year. These statistics compare with 59 deaths due to aspirin poisoning in 2003, 147 deaths associated with acetaminophen-containing products in 2003, and an average of 54 deaths per year due to lightning for 1990-2003.