DefinitionCalcium carbonate is an ingredient that is commonly found in antacids (for heartburn) and some dietary supplements. Calcium carbonate overdoseoccurs when someone accidentally or intentionally takes more than the normal or recommended amount of a product containing this substance.This is for information only and not for use in the treatment or management of an actual poison exposure. If you have an exposure, you should call your local emergency number (such as 911) or the National Poison Control Center at 1-800-222-1222.See also: Calcium carbonate with magnesium overdoseAlternative NamesTums overdose; Calcium overdosePoisonous IngredientCalciumWhere FoundProducts containing calcium carbonate, includingCertain antacids (Tums, Chooz)Certain mineral supplementsCertain hand lotionsCer