The Effects of Benadryl on Dogs

By Ellie Williams

Benadryl is the brand name for diphenhydramine, a human medication recommended by veterinarians to treat a wide variety of symptoms in dogs, including allergies. Consult with your veterinarian before administering to determine the appropriate dosage.

How It Works

Benadryl only treats symptoms, not the conditions that cause them. It eases allergies and allergic reactions by blocking histamine, a chemical that can cause inflammation and restrict breathing. When used to treat motion sickness, something it helps only in dogs, it works on the part of the brain responsible for vomiting. Benadryl is also used to treat loss of appetite, to lessen the symptoms associated with insect bites, to relieve coughing and to ease anxiety in pets who have difficulty traveling.

Potential Adverse Effects

Benadryl can cause dry mouth, decreased urination, diarrhea, vomiting, decreased appetite and drowsiness or sedation. It should not be used in animals who are pregnant or nursing. In addition, it should not be administered to animals who suffer from glaucoma, high blood pressure, urinary obstruction or prostate conditions. Caution also must be used when given to dogs who have hyperthyroidism, bladder problems or heart disease. Some medications, such as sinus or cold medicines, could interact badly with Benadryl.