antihistamine

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Related to Chlorphenamine: chlorpheniramine maleate

antihistamine

 [an″te-, an″ti-his´tah-mēn]
a drug that counteracts the effects of histamine, a normal body chemical that among its actions is believed to cause the symptoms of persons who are hypersensitive to various allergens. While the term antihistamine can broadly include any agent that blocks any histamine receptor, in practice it is usually used to denote those blocking the H1 type of receptors (H1 receptor antagonists), those involved in allergic reactions. Agents blocking the H2 type of receptors are usually called histamine H2 receptor antagonists, and include the agents used to inhibit gastric secretion in peptic ulcer.

Antihistamines are used to relieve the symptoms of allergic reactions, especially hay fever and other allergic disorders of the nasal passages. Some antihistamines have an antinauseant action that is useful in the relief of motion sickness. Others have a sedative and hypnotic action and may be used as tranquilizers. Many are ingredients of compound preparations used to treat coughs or the common cold.

Patients for whom an antihistamine has been prescribed should be instructed about the side effects of these drugs, including drowsiness, dizziness, and muscular weakness. These side effects present a special hazard in driving an automobile or operating heavy machinery. Other side effects include dryness of the mouth and throat and insomnia.

antihistamine

(ăn′tē-hĭs′tə-mēn′, -mĭn, ăn′tī-)
n.
A drug used to counteract the physiological effects of histamine production in allergic reactions and colds.

an′ti·his′ta·min′ic (-mĭn′ĭk) adj.

antihistamine

An agent that counteracts the effects of histamine released during allergic reactions by blocking histamine (H1) receptors.
 
Adverse effects
Dry mouth, drowsiness, urine retention in men, tachycardia.

antihistamine

Antihistaminic Pharmacology An agent that counteracts the effects of histamine released during allergic reactions by blocking histamine–H1 receptors Adverse effects Dry mouth, drowsiness, urine retention in ♂, tachycardia. See Histamine receptor.

antihistamine

One of a group of drugs which act against histamine-a powerful and highly irritant agent released in the body by MAST CELLS, after contact with certain ALLERGENS. Antihistamine drugs fall into two groups-those that block H1 receptors and act mainly on blood vessels, and those that block H2 receptors and act mainly on the secretion of acid in the stomach. H1 receptor blockers include diphenhydramine, chlorpheniramine (chlorphenamine) (Piriton), terfenadine (Triludan), promethazine (Phenergan), cyproheptadine (Periactin), mequitazine (Primalan) and phenindamine (Thephorin). H2 receptor blockers are not usually referred to as antihistamines, although this is what they are. They include CIMETIDINE (Tagamet), and RANITIDINE (Zantac).

antihistamine

see ALLERGY.

Antihistamine

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

antihistamine 

Any substance that reduces the effect of histamine or blocks histamine receptors, usually the histamine 1 (H1) receptor. It is used in the treatment of allergic conjunctivitis and also in the temporary relief of minor allergic symptoms of the eye. Common agents include antazoline sulfate, azelastine hydrochloride, cetirizine, chlorphenamine, emedastine, epinastine hydrochloride, ketotifen, levocabastine, loratadine and olopatadine. See hypersensitivity; mast cell stabilizers.
References in periodicals archive ?
Further adrenaline 100mcg IV, hydrocortisone 200mg IV and chlorphenamine 10mg IV were given.
They're unsightly but don't do any harm." You Could Try: An oral antihistamine called chlorphenamine if the lumps itch, though it can cause drowsiness.
a) Acrivastine b) Cetirizine c) Chlorphenamine d) Loratadine
Some of the most dangerous (score three) drugs are commonly available and include the antihistamines chlorphenamine (used in the brand Piriton) and promethazine (used in Phenergan), anti-depressants amitriptyline (used in several brands) and paroxetine (used in Seroxat) and the incontinence drug oxybutynin (used in Ditropan).
Associate director of pharmacy Anne Joshua said: "Antihistamines such as chlorphenamine and promethazine have been used for many years to treat adults, including pregnant women, and children.
Suitable oral antihistamine-containing products include chlorphenamine, clemstine, acrivastine, azelastine, loratidine and cetirizine.
He had tried different across-the-counter treatments and usually used Piriton - the brand name for Chlorphenamine (which is also marketed under the name Boots Allergy Relief Antihistamine Tablets).
Chlorphenamine, an ingredient in Tixylix Cough and Cold, was mentioned in reports of 11 deaths.