Chlorpheniramine is an antihistamine medication used as an active ingredient in many different non-prescription products (such as Chlor-Trimeton®) and prescription drugs (such as Tussionex®). It is used to treat allergies, hives, and the common cold. The medicine is available in several different forms, including liquid, capsules, and tablets. Chlorpheniramine tablets come in both immediate-release and extended-release forms. The medication is taken by mouth every 4 to 12 hours, depending on the particular product.
Chlorpheniramine is part of a class of drugs called antihistamines. Specifically, it is an H1 receptor antagonist. This means that it blocks a specific type of histamine receptor in the body known as H1 receptors. Since allergic reactions are partly caused by the release of histamine from certain cells in the body, chlorpheniramine can help relieve or prevent allergy symptoms.
Chlorpheniramine also blocks acetylcholine receptors, an action that produces some of the unpleasant side effects of the medication, such as dry mouth or difficulty urinating, but also helps to relieve a runny nose.
(Click Chlorpheniramine for more information on when and how to take chlorpheniramine tablets, what side effects may occur with this medication, and warnings and precautions to discuss with your healthcare provider.)