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Antihistamines treat symptoms of allergic reactions such as stuffy or runny nose, sneezing, itching, and hives. Antihistamines are available Category:OTC Drugs over the counter]] as well as by prescription. They may be taken orally or sprayed into the nostrils. Some patients may use antihistamines on a daily basis to stop allergy symptoms from appearing. Other patients may take antihistamines on an as-needed basis when they begin to exhibit signs of an allergic reaction.[1]

Antihistamines work by blocking substances called histamines in the body. Histamines are responsible for symptoms of allergies. Taking antihistamines does not cure allergies, but only relieves symptoms.[2]


Flickr: °Florian
Uses Treat allergy symptoms[1]
Symptoms treated Runny nose, sneezing, swelling, itching, hives[2]
Prescription needed? Some products are OTC, others prescription[2]
Brand names Benadryl®, Allegra®, Zyrtec®[2]
Active ingredients Diphenhydramine, fexofenadine, cetirizine[2]
Disclaimer The information provided by is not a substitute for professional medical advice, diagnosis, or treatment. Do not take any action based on the information on this page without consulting a physician.
Author Selena Robinson


About Antihistamines

Brand names of OTC antihistamines include Benadryl®, Zyrtec®, Allegra®, Claritin®, Clarinex®, and Astelin®. Zyrtec®, Allegra®, Astelin®, and Claritin® are among the newest classes of antihistamines. It is not safe to mix any antihistamines with alcoholic beverages. In addition, patients with certain medical conditions may experience problems with antihistamines. These conditions include glaucoma, enlarged prostate or problems urinating, overactive thyroid, high blood pressure, heart disease, diabetes, or epilepsy.[1]

Antihistamines may cause side effects in some users. Common adverse reactions include anxiousness or nervousness, dryness in the mouth, dizziness, reduced desire for food, and changes in vision. Nosebleeds or symptoms that do not improve may be signs of a more serious condition.[1]


Other Antihistamine Uses

The antihistamine diphenhydramine, which is the active ingredient of Benadryl®, is used in some sleeping pills sold over the counter. Sleepiness is noted as a side effect of this antihistamine; however, newer antihistamines do not cause as much drowsiness. In addition to treating insomnia, diphenhydramine may also be prescribed to treat motion sickness, as well as to treat unusual movements in sufferers of Parkinson's disease. In some cases, this antihistamine is also prescribed to treat side effects caused by other medications.[3]

Drug Side Effects

Drug Side Effects


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