Antihistamine Treatment for Hives in Dogs

Hives in dogs can occur as a reaction to different agents including drugs, foods or different particles that are airborne. The classic treatment for hives includes the administration of antihistamines. When the dog's body encounters the allergen, the immune system recognizes the allergen as a menace for the dog and will produce histamines and inflammatory cells. The antihistamines are effective in counteracting with the histamines.

Antihistamines for Hives in Dogs

Antihistamines have given good results in controlling allergic reactions in dogs. The antihistamines act as a stopper agent when the histamines are produced in the dog's body. The histamines are a reaction of the immune system. The effectiveness of antihistamines for hives in dogs is between 25% and 60%, and most vets will combine this type of treatment with a change in diet or supplementation of omega 3 fatty acids.

The main downside of antihistamines is the fact that if they are administered for more than three months, the dog's body can become immune and no longer respond to the medication. It is essential to change the type of antihistamines used every three months to prevent this from happening.

Antihistamines Used in Dogs

The antihistamines that may be used in dogs with hives include:

  • Benadryl is the most common antihistamine designed for use in humans, but may also be applied to dogs. When the dog has received Benadryl for three months he should get Diphenhydramine, which is very similar to Benadryl
  • Chlorpheniramine
  • Tavist or Clemastine, which have comparable effects
  • Cyproheptadine
  • Seldane
  • Atarax, giving effective results in a great number of dogs with hives

These antihistamines can be alternated and the vet may try several drugs before deciding which is best for your dog.

Antihistamine Side Effects

Typically, the antihistamines will not cause major side effects in canines, but there may be a few side effects that can occur including:

  • Nausea and vomiting
  • Dry mouth or mucous membranes
  • Constipation or diarrhea
  • Ataxia
  • Confusion
  • Behavioral changes
  • Upset stomach
  • Urinary tract infections
  • Lethargy

If the antihistamines are given over a long period of time, these can cause kidney problems and may also affect the dog's vision.


The antihistamines shouldn't be administered to dogs that are allergic to any of the compounds of the drug. If the dog develops severe side effects, the administration of antihistamines should be discontinued.

Alternative Treatment Options

Hives occur in dogs that have a reduced immunity, so immune system supplements are always recommended for dogs that develop hives. However, the best treatment is avoiding the agents that cause hives. This can be possible if the irritants are ingredients in the dog's food or drugs. Pollens, dust or grasses that cause hives cannot be avoided. Alternative treatments for hives include: