Can Cats Have Allergies?

Medical articles
cat sneezing

Believe it or not, cats can have allergies just like people. They can experience seasonal allergies; allergies to food; allergies to dust, mold, and dander; insect bite hypersensitivities; and allergic reactions. Cat allergy symptoms are usually a little bit different than what is seen in people, so it isn’t always obvious a pet is dealing with an allergic disorder. Read on for additional insights into allergies in the cat.

What Are Cats Allergic To?

Common cat allergies are food, pollen, insect bites, mold, and dust. According to several studies by veterinary scientists, the most common foods that cats are allergic to are beef, chicken, and fish. Flea bite hypersensitivity is the most frequent insect allergy that cats experience, but bites from mosquitoes are also a common cause. Pollens, mold, and dust (i.e. including litter dust) are allergy culprits in many cats as well. It is important to understand that cats can be allergic to more than one allergen, making diagnosis and treatment a bit difficult for many pets.

Cat Allergy Symptoms

Allergies in cats often cause itching and skin infections, even food allergies. Cats will often scratch their head, neck, and sides. The skin may look red; develop sores and crusts; or ooze and bleed.

Some types of allergies cause tummy troubles - vomiting or throwing up and diarrhea or loose stools may be noted. The most common allergy to cause this type of gastrointestinal (GI) upset is a food allergy, which may occur with or without skin problems.

Watery eyes and sneezing, as seen with seasonal allergies in people, can also be a sign of allergies in certain cats. Sometimes these upper respiratory symptoms are the result of a secondary bacterial infection that developed because of the allergies. If this happens, the symptoms may worsen and can lead to fever, laying around more, and poor appetite.

Asthma, also known as feline allergic bronchitis, is also a common symptom of allergies in cats, especially with dust, pollen, and mold. Wheezing, trouble breathing, coughing, and breathing with the mouth open are notable symptoms is cats with asthma.

Diagnosing Allergies in Cats

In some cases, a veterinarian may become suspicious of allergies in a cat based on the history, symptoms, and physical examination. For example, if a cat has a skin infection whenever he has fleas, he may have a flea bite hypersensitivity type of allergy. If he develops skin infections or sneezing/watery eyes at certain times of the year, the veterinarian may suspect a seasonal pollen allergy.

To diagnose most types of allergies, blood tests (sometimes known as radioallergosorbent test/RAST test or allergen-specific IgE serology/ASIS serum test) or intradermal skin testing can be done. For the blood test, a blood sample is drawn from the pet and sent to a lab. The skin test involves injecting small amounts of allergens in liquid form under the skin. Intradermal skin testing is usually performed by a veterinary dermatologist because it is more difficult to do. Pets often need to be off any allergy medications for at least 2 weeks before these tests can be performed.

Other tests include bronchoalveolar lavage, a technique that involves washing small amounts of fluid through the lower respiratory tract under anesthesia, then drawing it back out to examine cells/debris and to perform microbe/parasite cultures. X-rays may be performed in cats that have asthma symptoms to help diagnose allergic bronchitis. 

Food allergies are more difficult to diagnose because blood and skin tests cannot identify them well. Because of this, if a food allergy is suspected, a food trial will often be tried. This consists of either a novel protein and/or carbohydrate diet (protein and grain/starch the pet has never had before), hypoallergenic diet, or a hydrolyzed protein diet for at least 6-8 weeks. No other foods can be given during the trial, including treats and table scraps.

Hydrolyzed protein is a type of protein whose structure has been broken down to a point where it cannot be recognized as an allergen by the body. This type of diet is most common for a diet trial because it is the least likely food to cause an allergy. If the pet’s symptoms improve after 8 weeks, a food allergy is likely the culprit. The veterinarian may then start adding back foods to determine what the pet is allergic to; however, some pet owners choose to remain on the special diet to avoid any further discomfort to the pet, rather than worry about testing new foods and dealing with the return of symptoms.


In some cases, eliminating the allergy cause will solve the problem. Preventing flea infestations and avoiding foods a pet is allergic to (usually by staying on a special diet) are common examples. In other situations, such as mold, dust, dander, and pollen allergies, cat allergy medicine to control the symptoms can be tried. Antihistamines; medicated sprays and shampoos; and steroids are common first options. Steroids are not ideal long-term and are usually only used to control the initial itching or breathing discomfort. If medications are needed long-term, allergy-specific immunotherapy injections, certain types of antidepressants, or cyclosporine may be prescribed.

Any infections will need to be dealt with, so antibiotics and/or anti-yeast medications may be prescribed as well. Medications to clear up diarrhea or a persistent cough may also be needed (depending on the pet’s symptoms). If asthma is diagnosed, medications such as an albuterol inhaler may be prescribed to help improve breathing. Steroids or cyclosporine may be used long term if the cat’s symptoms are severe.

Know that as with many people’s allergies, cat allergies can be very frustrating to treat. Many different medications and/or foods may be tried before the most effective combination for the pet is found. Further, even if all the right medications, shampoos, foods, and treatments are given correctly, outbreaks of skin infections, upper respiratory symptoms, and/or asthma attacks can still happen. It is important to follow all veterinary recommendations, go to all scheduled rechecks, and discuss any issues or lack of improvement as soon as they occur. This will prevent any prolonged discomfort for the pet and help him improve quickly.