According to the Hartel Veterinary Hospital, animal antihistamines are safe for dogs, but human antihistamines can contain ingredients that are harmful to dogs. Hartel Veterinary hospital recommends that dog owners double check the ingredients of prescribed or over-the-counter antihistamines to ensure the medications only contain one active ingredient.
Chyenne Animal Hospital warns dog owners against purchasing combination antihistamine products such as cold and flu medicines or medicines that contain decongestants, as these medications often contain high levels of stimulants that can be toxic to animals. Benadryl is an over-the-counter allergy medication that contains the single ingredient of diphenhydramine, an antihistamine that is suitable for dogs.
According to Long Veterinary Clinic, approximately 70 percent of dogs experience seasonal allergies and atopy, an allergic reaction that effects the skin. Allergies in dogs are often treated with antihistamines. Antihistamines are most effective when used in conjunction with other therapies, as only one in five dogs shows symptom improvement with antihistamines alone. Allergies in dogs are similar to allergies in humans. Certain dogs develop sensitivities to dust mites, seasonal pollens, grass and dander. Animals typically experience allergic symptoms that affect the skin as opposed to respiratory distress, however, occasional sneezing and respiratory symptoms are possible. Atopy and allergic reactions to fleas are the most common skin diseases in dogs.