Antihistamine

antihistamine /an·ti·his·ta·mine/ (-his´tah-men) an agent that counteracts the action of histamine; usually used for agents blocking H1 receptors (H) and used to treat allergic reactions and as components of cough and cold preparations. Agents blocking H2 receptors, used to inhibit gastric secretion in peptic ulcer, are usually called H.

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an·ti·his·ta·mine (nt-hst-mn, -mn)

n.

Any of several drugs used to counteract the physiological effects of histamine.

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anti·hista·mine adj.

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Antihistamine

A drug that inhibits the actions of histamine. Histamine causes dilatation of capillaries, contraction of smooth muscle, and stimulation of gastric acid secretion.

Mentioned in: Anti-Itch Drugs, Antinausea Drugs, Lichen Simplex Chronicus, Physical Allergy, Serum Sickness

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antihistamine (an´tīhis´tmin),

n a drug that counteracts the release of histamine such as occurs in allergic reactions; also has topical anesthetic and sedative effects, as well as a drying effect on the nasal mucosa.

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antihistamine

a drug that counteracts the effects of histamine by acting on histamine receptors without activating them but preventing their accessibility to histamine. A competitive and reversible reaction. There are two types:

Those that block H₁ receptors are commonly referred to as the antihistamines and are widely used to relieve the symptoms of allergic reactions, especially urticaria. Some have an antinauseant action that is useful in the prevention of motion sickness and others have a sedative and hypnotic action.

H₂ receptor blocking agents inhibit the stimulation of gastric secretions.

See also histamine antagonists, H₂-receptor blocker.