antihistamine


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Related to antihistamine: decongestant

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 ?
Their research found that more than half (58%) of motorists suffering from hay fever had driven after taking antihistamines - and about 10% of those had felt the effects of the medication while driving.
When push comes to shove, experts say antihistamines are still the best and most effective way to tackle the worst of your hay fever symptoms.
She said drivers should aim to take non-drowsy antihistamines like loratadine, cetirizine, and fexofenadine if they are planning on driving this Easter break.
Keywords: Charge transfer complexes, Antihistamines, Curcumin, Benesi-Hildebrand plot
The most annoying side effect that antihistamines produce is drowsiness.
Effective medications that can be prescribed by a physician include antihistamines, topical nasal steroids, and cromolyn sodium--any of which can be used alone or in combination.
"You're allergic," he told her, and prescribed a steroidal nose spray and a prescription antihistamine. The sinus infections disappeared.
Antihistamines are used widely by the general population, including women of child-bearing age, 20%-30% of whom have allergic conditions, primarily rhinitis and sinusitis (8).
Since many children with acute ear infections have cold symptoms caused by a virus, these same doctors recommend an antihistamine and/or a decongestant to relieve symptoms.
For those really bad days, when your sinuses are feeling the pressure, use an antihistamine that also features a decongestant for sinus control.
Data from the National Ambulatory Medical Care Survey from 2003 to 2012 were used to assess antihistamine use in patients with AD.
Additionally, few studies focus on patterns of antihistamine use among older adults with dementia in Japan.