It's best to talk to a vet before choosing an antihistamine for dogs, but for acute allergic reactions, experts often recommend...
Dog Care

How Do I Choose the Best Antihistamine for Dogs?

Susana Bradford
2 minute read
September 6, 2021

Antihistamines are often used to treat dog allergies. Common antihistamines used as canine medication include diphenhydramine, chlorpheniramine, clemastine fumarate and hydroxyzine. Each individual dog will react differently to a given medicine. For guidance, take your dog to be examined by a veterinarian.

Diphenhydramine can be an effective antihistamine for dogs when used for acute reactions, such as those that occur in response to a vaccination, blood transfusion or dog bee sting. It is also used to treat itchiness and swelling in dogs. The effects of airborne allergens on dogs can also be mitigated through treatment with diphenhydramine. Veterinarians usually recommend 1 mg of diphenhydramine per pound of the dog's weight.

Another commonly used antihistamine for dogs is chlorpheniramine. Like diphenhydramine, its efficacy is highest when used to treat acute allergic responses to things like snake and insect bites and reactions to vaccinations and blood transfusions. Chlorpheniramine can help in the treatment of mast cell tumors, which are growths comprised of histamine, the substance that provokes allergic reactions. Dosage advised by veterinarians is usually three tablets per day.

Also recommended as an antihistamine for dogs is clemastine fumarate. It is one of the most effective antihistamines for dogs that suffer from itchy skin. Clemastine fumarate is a comparatively expensive antihistamine, but many dog owners choose it not only for its efficacy but also because it is usually given only twice a day, less often than most other canine antihistamines.

Hydroxyzine is an antihistamine that tends to be effective for treating itchy skin. It's also useful in the treatment of acute allergic reactions to bites, stings and vaccinations. Dosing depends on the individual dog and must be recommended by a veterinarian. Dog owners often like to treat their pets with hydroxyzine because of its availability in small tablets that are easy to administer to canine patients.

The effectiveness of antihistamine for dogs is thought to be heightened when it is supplemented with omega-3 fatty acids. These substances help reduce the inflammation involved in allergic reactions. Omega-3 fatty acids combined with antihistamine are particularly effective for the treatment of itchy skin.

Side effects of antihistamines include sedation and the reduction of nausea. Veterinarians sometimes recommend antihistamine for dogs that suffer from motion sickness or require tranquilizing. Other side effects of antihistamines can include seizures, diarrhea and liver damage. Since antihistamines are strong medicines, it is best to consult a veterinarian before administering them to dogs.

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Meet the author:

Susana Bradford

Susana is an avid animal lover and has been around animals her entire life, and has volunteered at several different animal shelters in Southern California. She has a loving family at home that consists of her husband, son, two dogs, and one cat. She enjoys trying new Italian recipes, playing piano, making pottery, and outdoor hiking with her family and dogs in her spare time.