medical Definition of clemastine
: an antihistamine drug administered orally in the form of its fumarate C21H26ClNO·C4H4O4 to relieve the symptoms of hay fever and the common cold
- … oral antihistamines, such as chlorpheniramine and clemastine, reduce sneezing and, to a lesser extent, rhinorrhea, probably because of their anticholinergic effects, but they are often associated with excess sedation.
- —Frederick G. Hayden, Scientific American Medicine Bulletin, March 1997
