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.
Vitamin C has a brief, pronounced laxative effect when taken in large amounts, typically in the range of 5-20 grams per day in divided doses for a person in normal "good health," although seriously ill people, may take 100-200 grams without inducing vitamin poisoning.
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.
Death by vitamin poisoning appears to be quite uncommon in the US, typically none in a given year. Before 1998, several deaths per year were 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 of iron have since reduced deaths to 0 or 1 per year. These statistics compare with 59 deaths due to aspirin poisoning in 2003 and 147 deaths associated with acetaminophen-containing products in 2003.