DefinitionDimenhydrinate is a type of medicine called an antihistamine.Dimenhydrinate overdose occurs when someone accidentally or intentionally takes more than the normal or recommended amount of this medication.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.Alternative NamesDramamine; DimetabsPoisonous IngredientDimenhydrinateWhere FoundDimenhydrinate is an ingredient found in some allergy medicines, as well as medicines used to treat nausea, vomiting, and seasickness.It may be found in:Calm-XDimetabsDramamineGravolHydrate bulletMarmineNico-VertTriptoneNote: This list may not be all-inclusive.