antihistamine

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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 ?
The doctor or the nurse is trained to evaluate and decide if the child's condition can be managed by an anti-histamine pill or he requires an Epi Pen jab.
Anti-histamine with Solucortif###9 (23.7%)###6 (16.7%)
If there is any swelling on their face or around the mouth, or strange breathing, call an ambulance and give anti-histamine medicine.
Quercetin, found naturally in onions, apples and black tea, is also noted for its anti-histamine activity.
Joseph Cough Suppressant) or the anti-histamine diphenhydramine (found in products including Allerdyl, Benadryl, and Dytuss).
Typically, these over-the-counter medicines combine some type of analgesic with an anti-histamine; all with the intent of helping us get to and stay asleep.
The HY * TEC BHR [TM] is a competitive assay based on a mouse monoclonal anti-histamine antibody-alkaline phosphatase conjugate.
Medical experts advise that the first line of treatment for hay fever is an oral anti-histamine - most are readily available from a pharmacy without prescription, but it's a good idea to check with the pharmacist whether they're suitable for you.
"Whilst in some cases it may be necessary to see a doctor, many anti-histamine medications can be bought over the counter."
Local skin reaction in one study has led to the recommendation that an anti-histamine be administered prior to infusion.
Use a non-drowsy anti-histamine tablet and a steroid nasal spray.