H1 receptor antagonist, any of a large number of agents that block the action of histamine by competitive binding to the H1 receptor. Such agents also have sedative, anticholinergic, and antiemetic effects, the exact effect varying from drug to drug, and are used for the relief of allergic symptoms and as antiemetics, antivertigo agents, sedatives, and antidyskinetics in parkinsonism. This group is traditionally called the antihistamines. See also antihistamine.
