Astemizole (brand name Hismanal; Janssen Pharmaceutica, Titusville, New Jersey, USA) is an anti-allergy medication that acts by suppressing the production of histamine, which is the chemical that is immediately produced by the body after exposure to an allergy-inducing agent, or allergen. Although astemizole was initially accepted as an effective antihistamine, its production and distribution was discontinued due to the overwhelming number of reports of severe adverse events involving the cardiovascular system, particularly when higher doses of the drug were administered.

Allergies are hypersensitive reactions of the body that involve histamine production, which in turn triggers inflammation of the sinuses as well as production of mucous in the nose and tears in the eyes. Histamine secretion can also result in an itchy skin rash, often known as ...