Antihistamine Drugs and Dosages
Note: The following information is provided as a reference and is not intended to replace veterinary care. Your veterinarian will make specific recommendations based upon the particular needs of your pet.
In general, antihistamines are intended for maintenance of allergic conditions. They are typically effective only in the face of mild itchiness and will appear to have little or no effect if the patient is already extremely itchy. If the itchiness is severe, or if the pet has secondary skin infections, your veterinarian will likely prescribe additional medications.
Antihistamine trials are best performed once the pet’s allergic condition is under reasonable control. The idea is to find the antihistamine drug that best suits the pet for maintenance and prevention of future allergic flair-ups. Any antihistamine drug that is used should be given for at least one to two weeks to assess its effectiveness and should not be given concurrently with any other antihistamine. In general, we recommend trying 3-4 different products before giving up on antihistamines.
Brand names may vary – generic products are typically available and effective. Side effects are typically minimal but can occur. The most common side effect is drowsiness. Stop the medication and contact your veterinarian if side effects occur. Be sure to check the product label and make sure it does not contain any other active ingredients, such as pseudophedrine or a nasal decongestant, which is often indicated by a “D” after the product name.