Hesperian Health Guides

Antihistamines: Medicines for Allergy

Itching, sneezing, and rashes caused by allergy can usually be treated with antihistamines. Any antihistamine works about as well as any other. So you if you do not have chlorpheniramine (described below), use diphenhydramine or another antihistamine in the right dose (this will vary for each drug). All antihistamines make people drowsy, but some more than others.

     These drugs are not helpful for the common cold.

     For a severe allergic reaction where there is difficulty breathing, epinephrine (adrenaline) is needed as well as antihistamines.

Chlorpheniramine, chlorphenamine


Chlorpheniramine is an antihistamine that reduces itching, sneezing, rashes, and other problems caused by allergies. It can be used after an insect bite, a mild food or drug allergy, or for “hay fever” (sneezing and itchy eyes from pollen in the air).

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Sleepiness (but this is less likely than with other antihistamines).

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1 to 2 years: give 1 mg, 2 times a day until the person feels better.
3 to 5 years: give 1 mg, every 4 to 6 hours until the person feels better.
6 to 12 years: give 2 mg, every 4 to 6 hours until the person feels better.
Over 12 years: give 4 mg, every 4 to 6 hours until the person feels better.


For severe allergic reaction, first inject epinephrine. Following with an injection of chlorpheniramine will help prevent the reaction from coming back when the epinephrine wears off. (If you do not have injectable chlorpheniramine, give tablets by mouth in the doses listed above.)
1 to 5 years: inject 2.5 to 5 mg, every 4 to 6 hours until the signs of allergic reaction are gone.
6 to 12 years: inject 5 to 10 mg, every 4 to 6 hours until the signs of allergic reaction are gone.
Over 12 years: inject 10 to 20 mg (no more than 40 mg in 24 hours), every 4 to 6 hours until the signs of allergic reaction are gone.


This page was updated:25 Nov 2019