Cat Antihistamine Medications

A cat with a feline allergy produces histamine to help his body cope with the affecting allergen. The histamine, in fact, is what produces the common symptoms of feline allergies. To combat these symptoms, your veterinarian may prescribe a cat antihistamine for allergy relief. Before you can treat your cat's allergies, however, you must first be able to recognize the common symptoms.

Feline Allergy Symptoms

Cats may be allergic to fleas, dust, pollen, mites or food. Each of these agents may produce a range of symptoms in a cat suffering from feline allergies. Your cat's reaction to an allergen may be relatively consistent, or it may become better or worse depending on the time of year. Some of the most frequent symptoms of cat allergies are:

  • Irritation of the face and legs (pawing or chewing)
  • Loss of hair
  • Breathing difficulties
  • Vomiting and diarrhea
  • Itchiness and irritated skin

Your veterinarian can test your cat for allergies by taking a small blood or skin sample, or by a process of trial and error by which a variety of allergens are introduced into your cat's system individually as a veterinarian watches for any allergic reactions.

Some of the Most Common Allergy Medications for Cats

There are a number of popular antihistamines and other medicines used to treat feline allergies. These include:

  • Cat benadryl substitutes (such as diphenhydramine)
  • Chlorpheniramine
  • Cyproheptadine

Corticosteroids (such as dexamethasone, methylprednisolone or prednisone) All of these medications require a veterinary prescription. Some may be available in generic form at a lower cost. Different types and severities of allergy may require unique treatment plans. It is best to consult with your vet to determine which plan will be best for your cat.

Benadryl-type Cat Medicine

Benadryl is an antihistamine used to treat human allergy symptoms. There are several closely related drugs that have been developed for feline allergies. These medicines are typically used to treat symptoms of flea allergies and atopy (dust and pollen allergies).


Chlorpheniramine is a low-cost antihistamine medicine used to treat a variety of allergy symptoms. A typical chlorpheniramine regimen will require that you give your cat several doses daily. Therefore, some people opt for treatment plans that are less time-intensive and easier to manage, or for plans that don't require that you give your cat dose after dose of medicine.


Cyproheptadine is used to treat respiratory problems related to feline allergies. It is usually prescribed in oral form.


Corticosteroids are potent drugs that can dramatically improve your cat's allergy symptoms. Because of their side effects, however, they can also make your cat sick if used improperly or for too long. Some of the common side effects of corticosteroids used to treat feline allergies are:

  • Liver damage
  • Frequent drinking and urinating
  • Hair loss
  • Distended abdomen

Overall, cats are less susceptible to the adverse effects associated with prolonged corticosteroid use than dogs. However, some cats may develop serious health problems. If you are considering a medicine regimen that includes corticosteroids to relieve your cat's allergies, speak with a veterinarian about potential side effects and possible alternative drug treatments.