Major Uses

Chlorpheniramine is an antihistamine that is most commonly used to treat symptoms of allergies and allergic reactions in both dogs and cats. Chlorpheniramine is one of the more commonly used antihistamines used in treating pruritus in cats. In some cases, Chlorpheniramine is used as a tranquilizer to calm excited animals.

Common Precautions

Side effects most commonly associated with Chlorpheniramine are lethargy, sedation, vomiting, diarrhea, and loss of appetite. Animals with glaucoma, lung disease, high blood pressure, asthma, heart disease, or prostate gland enlargement should not be treated with Chlorpheniramine.

Chlorpheniramine should not be administered in animals with a known allergy or hypersensitivity to the drug. Chlorpheniramine may interact with other medications including barbiturates, tranquilizers, and heparin. This should be discussed with a veterinarian. Emergency veterinary care should be sought if an animal experiences any unusual symptoms.


Chlorpheniramine should be stored in a tight, light resistant container. All forms of Chlorpheniramine should be stored at room temperature.


Chlorpheniramine is available in 2mg, 4mg, 8mg, and 12 mg tablets, 2mg/5ml oral syrup, and 10mg/ml or 100mg/ml liquid injectable.

A typical dose range for Chlorpheniramine in dogs is 4-8 mg/kg (maximum of 0.5mh/kg) PO q8-12h PO. Dose may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose is missed, it should be administered as soon as possible. If it is almost time for the subsequent dose, the missed dose should be skipped and the regular administration schedule resumed. Two doses of Chlorpheniramine should not be administered at the same time.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.