Allergies in Cats: Common Allergens & Allergy Treatments

If your kitty has allergies, they may be scratching and licking all day and night, even to the point of developing bald patches or rashes on their skin. Or, maybe you’ve noticed digestive upset or “hay fever” type symptoms.

Either way, you’re probably asking yourself how you can help your furry friend feel better. Here’s what you should know when it comes to your cat’s allergies.

What Do Cat Allergy Symptoms Look Like?

To understand allergy symptoms, it’s important to know what allergies are.

Allergies are an overreaction of your cat’s immune system. For example, if the immune system detects pollen or dust or an ingredient in your cat’s food, those substances get treated like a foreign invader — as if they were a virus or bacteria.

Part of the immune system’s response is to release histamine, which results in a lot of inflammation. This may show as symptoms in the upper respiratory system, digestive system, or (most commonly) the skin.

Inflammation causes redness and itchiness, and it disrupts the normal protective skin barrier. Between inflammation and trauma from your cat’s licking and scratching, wounds and secondary skin infections with bacteria or yeast are common.

Here are some of the most common allergy symptoms in cats:

Itchy or red skin, especially on the head, face, ears, neck, paws, belly, and limbs.
Hives, bumps, scabs, rashes, or swellings on the skin.
Skin wounds or infections.
Ear infections.
Fur or hair loss. You might also notice hairballs due to increased hair ingestion.
Red, itchy, or watery eyes.
Sneezing or a runny nose.
Coughing or wheezing (common in kitties who have asthma).
Lip or mouth ulcers (less common).
Diarrhea or vomiting, or other digestive symptoms (less common).
Anaphylactic reaction, which may include facial swelling, sudden vomiting or diarrhea, difficulty breathing, collapse, and even death. Fortunately, this is not common — you’re very unlikely to see an anaphylactic reaction due to seasonal, flea, or food allergies. But if you ever notice these symptoms in your pet (especially after something like a bee sting, vaccine, or new medication), bring your cat to a vet immediately.

Your pet may display several of the symptoms above, or just one or two. Any of these symptoms, especially if they happen frequently, are enough to consider allergies as a possible cause. And, it's best to visit your vet to properly diagnose and treat your furry friend.

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What Are Cats Allergic To?

Not all felines with allergies have the same condition. Symptoms can range from mild to severe, and they may affect several different areas of the body.

There are many different types of allergens your pet can be sensitive to. Some cats may have just one type of allergy, while others may suffer from more than one.

Below are common types of cat allergies.

Cat Environmental & Seasonal Allergies

Environmental allergies mean your cat is allergic to pollen (from trees, grasses, or weeds), molds, dust, mildew, dander, dust mites, or other inhaled allergens. The list of potential allergens is very long, and varies depending on which plants are found in your climate.

Usually, symptoms occur due to inhaling these allergens, but direct skin contact with allergens can also cause symptoms. Just like environmental allergies in humans, symptoms tend to be seasonal. But symptoms may worsen and become year-round over time.

Commonly environmental or seasonal allergies are inherited, in which case it’s known as “atopy.”

Cat Flea Allergies

Flea allergy is so common in cats that the resulting skin condition has its own name: Flea Allergy Dermatitis (FAD).

Technically, though, your cat isn’t allergic to fleas — they’re allergic to flea saliva. This is different from normal itchiness in response to a bug bite. Instead, cats with flea allergies will compulsively lick and scratch, often chewing their skin raw and causing an infection. In addition to the site of the flea bite, the entire body might be affected. This can happen after as little as 1-2 flea bites, and the itchiness may last for more than a week!

Diagnosing a flea saliva allergy can be tricky because you might not see the flea(s). Cats are excellent groomers, so they may clear away the “evidence.”

Cat Food Allergies

Food allergies are not nearly as common in cats as most pet parents think they are — in fact, food allergies only account for 10% of allergy-afflicted pets!

However, it’s still important to consider food allergies when figuring out what’s causing your feline friend's symptoms. Your pet may be allergic to just one ingredient, or several — and new food allergies can develop over time. Cats may even develop an allergy to a food they’ve eaten their entire life.

The most common cat food allergies include proteins found in beef, chicken, dairy, wheat, eggs, or fish. There’s nothing inherently wrong with these foods (just as there’s nothing wrong with peanuts or shellfish or other common allergens for people), but your cat must avoid foods containing any ingredient they are allergic to.

Cat food allergy symptoms usually show up in the skin as redness, itchiness, fur loss, and scabs or wounds secondary to your cat scratching and licking.

About 10-15% of cats with food allergies will have digestive symptoms, such as vomiting and diarrhea. If digestion is impaired, this may also affect your kitty’s weight or their ability to absorb and process all the nutrients they need.

It’s also important to note your pet may have symptoms due to a food intolerance. This is different from a true allergy because the immune system is not involved, so some allergy treatments won’t work for food intolerance. Instead, difficulty digesting or processing a certain ingredient is to blame.

Other Allergies That Can Affect Cats

Most allergic pets fall into one of the above categories. But there are other possibilities.

Contact allergies affect some cats. For example, a fairly common condition happens when a cat is allergic to plastic. For these kitties, plastic food bowls lead to “chin acne,” or skin lesions caused by their chin touching the plastic while they eat. Certain fabrics, laundry detergents, cleaning products, etc. can also cause contact allergies.As described above, anaphylactic reactions are also possible.

And some pets may suffer from reactions to other inhaled substances like perfume, scented kitty litter, or smoke.

What Causes Allergies in Cats?

Allergies tend to be genetic or inherited. Unfortunately, this means allergies are difficult to avoid.

Cat allergies can show up at any age, and may get worse over time. Any breed of cat may be affected.

How Are Allergies Diagnosed in Pets?

Allergy testing requires patience. There’s a process to go through to reach an accurate diagnosis — and therefore the best treatment option — for your furry friend.

The first step usually involves ruling out other medical or emotional conditions that could cause similar symptoms. For example, a urinary tract infection may cause a kitty to lick their belly until the skin in that area is bald. A bored or anxious cat may do the same thing. And respiratory infections can mimic hay fever symptoms.

Testing for other conditions usually starts with a gentle skin or ear swab/scrape at your vet visit, to look for bacteria, yeast, mites, or other abnormalities. Bloodwork and other diagnostic tests may be needed, too.

If allergies are suspected, here are some common next steps:

Evaluating for food allergies via an elimination diet. Blood tests are not as accurate for food allergies, so a food trial should be used. This is a strict diet on a type of food that is unlikely to cause allergies in your cat, for 1-3 months. It’s best to do this under your veterinarian’s guidance.
Evaluating for environmental allergies. Blood tests are common, and skin tests may also be performed, usually by a veterinary dermatologist. These tests help pinpoint the offending allergen. Often, these tests are customized to include allergens specific to your climate, state, or city.

How Are Cat Allergies Treated?

Unfortunately, there is no cure for allergies, but treatment is possible.

It’s important to remember that treatment means managing allergies, not curing them. Keeping this goal in mind will help you set realistic expectations, avoid frustration, and plan the most effective long-term management strategy.

Below are some treatment strategies.

Flea allergies: Fleas can stick around even in harsh winters, and it only takes a couple of bites to set off a raging allergic reaction. Talk to your vet about the best flea control for your cat.
Food allergies: Your furry friend must stay on a strict diet with a food that you know does not cause allergy symptoms. Unfortunately, that usually means common treats, table scraps, and even flavored medications are off limits. Your vet can help you find alternative medications and hypoallergenic food that may be better tolerated.
Environmental allergies: Unfortunately, environmental allergens are harder to control, since you can’t change the pollen count. Pets with atopy or seasonal allergies may need treatments and medications long-term — given on a regular basis or just during flare ups, depending how bad their symptoms are. You can also consider desensitization therapy for environmental allergies. This means weekly injections, which are customized for your pet after allergy testing. The injections contain small amounts of the things your pet is allergic to, so your cat slowly builds up a tolerance. The downsides are that it can take many months to work and not all cats will have a significant improvement. But for kitties with severe symptoms, it may be worth trying.
Secondary infections, wounds, and other lesions: No matter which allergies your pet has, all resulting skin conditions must be treated promptly. Otherwise, they tend to get worse.

Other things you can do for your allergic cat, including home remedies, include:

Keep your kitty indoors. Leave windows closed to avoid outdoor allergens, especially if the pollen count is high.
Keep the home clean, change air filters regularly, and use dust-free litter.
Skin and allergy supplements, such as omega fatty acids or probiotics.
Use antihistamines such as Benadryl. Check with your vet for a safe formulation and dose for your individual pet. Never buy products that also contain decongestants or other ingredients.

Bathing and skin ointments may also help soothe your cat's skin, but it’s best to check with your vet first to discuss safe options. In addition to the difficulties of bathing a cat, your kitty’s grooming habits put them at risk of ingesting ointments, creams, or shampoo residue.

Allergies can be frustrating — both for you, and for your cat who can’t seem to find relief from their itchiness.

Fortunately, with patience, vigilance, and the right treatment plan for your individual feline friend, you can really make your cat feel better so they can enjoy all their favorite activities with you — itch free!