Seasonal Allergies in Cats

Michael Kearley, DVM
By Michael Kearley, DVM on Apr. 21, 2023
Ginger cat outside

iStock/Christopher Freeman

In This Article


What Are Seasonal Allergies in Cats?

Seasonal allergies are also called “atopic dermatitis,” or “atopy,” in cats and are often a result of a genetic defect in the skin barrier system, which allows more allergens to penetrate and cause effects such as itching and scratching, along with secondary skin and ear infections. Allergies are extremely frustrating both for cat and pet parent, as there is no quick cure.

Environmental allergies are often distinguished from other allergies due to their seasonality (causing symptoms in spring and summer), their predictability (by monitoring the pollen counts), their consistency in occurring year after year, and their progressive worsening over time.

Types of Seasonal Allergies in Cats

There are different types of seasonal allergies in cats, and each cat may react differently to one allergen than to another. Seasonal allergies and their related symptoms are usually first seen around 1–3 years of age, starting during the spring and summer months but then occurring year-round, progressively worsening as the cat gets older. Some of the most common seasonal allergies include:

  • Dander

  • Dust and storage mites

  • Flea saliva, seen more often in warmer months

  • Molds/spores

  • Pollens

    • Grasses—orchard, Bermuda, Bahia

    • Trees—pine, oak, ash, palm

    • Weeds—ragweed, cocklebur, sorrel

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Symptoms of Seasonal Allergies in Cats

Unlike people, cats generally don’t get a watery nose or puffy eyes from seasonal allergies. The most common symptom is itching, which leads to scratching and excessive grooming, and for cats this is usually accompanied by:

  • Hair loss—often by the neck, base of ears, base of tail, or groin; symmetrical along the back

  • Crusts, scabs, or irritated skin

  • Ear infections—often accompanied by inflamed or thickened ears

  • Eosinophilic plaque—reddish-yellow, ulcerated, itchy, thickened lesion on the groin or thighs

  • Indolent ulcer—inflammatory lesion, often disc-shaped, seen on the lips or skin

  • Eosinophilic granuloma—yellowish-pink, raised, linear lesion seen on the hind limbs

Causes of Seasonal Allergies in Cats

An allergen is a foreign substance or material that causes an immune reaction (an allergy). The symptoms of an allergic reaction range from mild to severe and can even be life-threatening.

Allergens can be inhaled, ingested, or directly come in contact with the skin—the most common cause of allergies. Cats are often allergic due to a genetic defect in their skin’s barrier, which allows the skin to be more permeable and thus prone to absorbing more allergens, which the immune system then reacts to.

How Veterinarians Diagnose Seasonal Allergies in Cats

Not all itching or scratching in cats is due to allergies. Your veterinarian may want to conduct a series of tests aimed at eliminating other causes. It’s important to note that there is no single test to diagnose atopic dermatitis. It is considered a diagnosis of exclusion, meaning it is diagnosed by excluding all other causes of itching first, along with supportive evidence such as the cat’s history and symptoms.

Part of arriving at a diagnosis of seasonal allergies is by ruling out food allergies by conducting a food trial and ensuring your cat is on a strict flea-control regimen. Having a positive response to allergy testing can also be indicative of this condition. 

As your cat may have secondary infections, your veterinarian may also want to conduct ear and skin testing to look for mites, fungus, and bacteria. If infections or lesions are severe enough, cultures or even skin biopsies may also be needed. 

Treatment of Seasonal Allergies in Cats

Bacterial and yeast infections, though secondary to the allergy, can increase your cat’s level of itching. Antibiotics and antifungals are usually required for treatment. Long-term treatment with topicals such as medicated shampoos or conditioners is often needed and can decrease the need for repeated antibiotic usage. Allergic cats typically require more frequent bathing than others. 

Because fleas can exaggerate allergy flare-ups, strict year-round flea control using a product such as Revolution® Plus or Comfortis™ is a must. Taking measures to prevent flea infestations, eradicating fleas in the environment when they occur, and ensuring that all pets in the home are on flea control is essential. 

Medications geared to relieve itching, such as steroids (prednisolone or methylprednisolone), are often prescribed. However, it’s important to note that without addressing the underlying cause, the itching will return, and long-term use of steroids can result in many health complications.

Antihistamines like diphenhydramine or chlorpheniramine are also commonly used to help control the itching, but the response varies depending on the cat. Antihistamines are also better used as a preventive before the allergy season starts. Never give your cat any human drug, including antihistamines, without consulting a veterinarian first.

Fatty acid/omega-3/fish oil supplements may also be recommended. These supplements are often beneficial at improving the skin barrier, decreasing inflammation, and reducing itch. Other immune-modulating drugs, such as cyclosporine (Atopica™), are also available for treating allergies long-term and can be beneficial for many cats.

As with any long-term medication, it is important to follow up with bloodwork every so often to ensure proper dosing and monitoring of side effects. Partner with your veterinarian to determine the need and frequency of future rechecks. 

Allergy Shots for Cats

Allergen-specific immunotherapy (ASIT), commonly referred to as “allergy shots,” is the most effective long-term therapy for seasonal allergies in cats. Though time-consuming and sometimes costly, these shots decrease the immune system’s response to the allergen over time and can dramatically improve your cat’s quality of life. Intradermal skin or serum testing may be done with a veterinary dermatologist to test which specific substance or substances cause a reaction.

The results of this test are then used to create a “vaccine,” which, when administered in increasing doses over time, decreases the cat’s overall sensitivity. Of course, the allergens included in the “vaccine” are chosen based on their severity as well as being endemic to the cat’s environment. 

Recovery and Management of Seasonal Allergies in Cats

Seasonal allergies or, for some parts of the United States, year-round allergies in cats are an extremely common cause of veterinary visits. Skin issues have a financial commitment and a large at-home care requirement. While the goal is to decrease the cat’s period of discomfort and flare-ups, pet parents need to know that even with the best of treatment, allergies will eventually recur, and are often lifelong.

ASIT, still considered the gold standard of treatment, is effective in only about 60-80% of cases, is a lifelong commitment, and requires a 9- to 12-month window to determine success. However, if your cat proves to benefit from ASIT, then keeping up with the injections will be a big investment toward improving your feline friend’s quality of life. 

Other beneficial measures include avoidance of the allergen, when possible, which may mean removing carpeted areas, uprooting plants and weeds, use of HEPA filters, and adhering to a strict flea-control regimen. Recovery cones, t-shirts, or other barrier methods may be useful, as are more frequent bathing and/or leave-on shampoos and conditioners.

Keeping your cat from licking and scratching will prevent future infections, as will monitoring the pollen counts and having the cat examined at the first sign of itching.

Michael Kearley, DVM


Michael Kearley, DVM


Dr. Michael Kearley graduated from the University of Florida College of Veterinary Medicine in 2013. He graduated with a certificate in...

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