Does My Cat Have an Allergy?

Cat ScratchingEnvironmental Allergies in Cats

Like people, cats may develop allergies to weeds, mold spores, pollen, grasses, feathers, or house dust. Environmental allergies are more common in dogs, but cats may also be afflicted. Symptoms include:

    • Itchy skin, which is indicated by excessive scratching, chewing, or licking
    • Hair loss
    • Patchy red spots on the skin

Diagnosis of environmental allergies is made through a process of elimination. A veterinarian will confirm that the itching and other symptoms are not caused by fleas, lice, mites, yeast or bacterial infections, or food allergies. Once other potential problems have been eliminated, serum testing may be performed to identify the environmental culprit.

Treatment for allergies varies depending on the specific allergy. In addition to removing or reducing the allergen in the home, it may involve:

    • Medicated shampoos
    • Antihistamines (these must be prescribed by a veterinarian – do not give your cat medications meant for humans)
    • Hyposensitization (allergy shots), whereby the pet receives a series of injections of the allergen in small doses to cause the production of antibodies
    • Having the pet wear an Elizabethan collar to prevent scratching and biting

Food Allergies in Cats

Many cats become allergic to certain foods, particularly dairy products, beef, corn, wheat, soya, eggs, and chicken. A cat may develop allergies to foods that she previously tolerated, so lack of prior reaction to certain foods does not rule them out as the cause of new allergy symptoms. Food allergy symptoms in cats may include:

    • Itchy skin and scratching, chewing, or excessive grooming, possibly even to the point of fur loss
    • Red, crusty skin, especially around the face (this symptom can also be caused by an allergy to plastic food dishes, which is easily remedied by switching to metal or ceramic dishes)
    • In some cases, gastrointestinal upsets such as diarrhea or vomiting

Treatment usually involves implementing a hypoallergenic diet to determine which ingredient is causing the problem and to prevent future allergic symptoms. Hypoallergenic diets contain nutritious ingredients such as duck, venison, or certain types of fish that are not commonly found in regular cat foods.

Flea Allergies in Cats

Many cats develop an allergy to flea saliva so severe that a single bite can cause them to engage in frenzied scratching, licking, and biting. Flea saliva allergy symptoms include:

    • Excessive scratching, over-grooming, or even biting out chunks of fur
    • Localized infections that cause patchy red spots and/or hair loss
    • Crusty, scabby sores

It may be difficult to find actual fleas on cats that suffer from flea allergy dermatitis (also known as flea bite hypersensitivity) because they tend to groom aggressively in order to remove them. Also, other external parasites, such as lice or mites as well as other allergies or infections can cause severe itching, so consulting a veterinarian to diagnose the problem is recommended.

Treatment for flea allergies may include medication dispensed by a veterinarian (essential fatty acids, steroids, or antihistamines) to treat the itching and other skin problems and preventative measures to ensure that both the cat and the home are free of fleas and flea eggs.

Other Causes of Allergy Symptoms in Cats

Before assuming that symptoms are caused by allergies, cats should receive a full veterinary check-up to rule out other possibilities, such as bacterial or fungal infections (i.e., ringworm) and other medical and/or psychological problems.

For more cat articles, see the main Cats page.


    • Davis, Karen Leigh. (1999). American Shorthair Cats. New York: Barron’s Educational Series, Inc.
    • Stonewall Veterinary Clinic. (n.d.). “Feline Allergies.”

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