Oral syrup and injectable forms should be stored in tightly closed, light resistant containers at room temperature. Not FDA approved for use in dogs and cats but it is a common and accepted practice to use chlorpheniramine in veterinary medicine. Available over the counter and by prescription. Histamine is released by certain cells during an allergic reaction. Symptoms include itching, sneezing, and swelling especially of the face.
Anaphylactic shock is a severe and possibly fatal allergic reaction.
One type of antihistamine may work better than another in some pets so trial periods of 1-2 weeks may be needed using different antihistamines to determine which works best at relieving the symptoms. Duration of treatment depends on the reason for treatment and response to treatment. They are per pet. Do Not use products in which chlorpheniramine is combined with other drugs or compounds such as caffeine or acetaminophen. Contents of slow-release capsules should not be allowed to dissolve on food before ingestion.