*Prescription Required: Vetsource®, our pharmacy provider, may need to contact your veterinary hospital for prescription verification. Learn More
Diphenhydramine is an antihistamine used to prevent allergy symptoms or relieve insect bites, stings and other causes of itching. Diphenhydramine may also be used for its sedative effect to calm an animal. This medication may be used for other conditions as determined by your veterinarian.
Side effects may include drowsiness, dry mouth, urinary retention, diarrhea, vomiting and lack of appetite. Drowsiness may diminish over time. Notify your veterinarian if these effects are troublesome and continue.
Other side effects may occur. If you notice anything unusual, contact your veterinarian.
Dogs and Cats
Diphenhydramine is used to stop allergy itching, prevent motion sickness, as a mild sedative and treat muscle tremors due to certain toxins or medications.
Diphenhydramine should be given orally as directed by your veterinarian.
This medication does not have an FDA approved indication for use in animals, but it is a common and acceptable practice for veterinarians to prescribe this human medication for use in animals.
This medication should not be used in pregnant or nursing animals.
Make sure to tell your veterinarian what other medication you are giving to your pet. Quite often your veterinarian may prescribe two different medications, and a drug interaction may be anticipated. In this case, your veterinarian may vary the dose and/or monitor your pet more closely. The following drugs can potentially interact with diphenhydramine: other CNS depressants, heparin, warfarin, and epinephrine. Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together.
Allergic reactions to medications may occur. Be sure to inform VetSource and your veterinarian if your pet has any known drug sensitivities or allergies. If your pet displays symptoms of an allergic reaction, call your veterinarian immediately or go to a veterinary emergency clinic. Symptoms may include but are not limited to: swollen lips, tongue, face, airways; difficulty breathing; agitation; profuse salivation; vomiting; widespread hives and itching.