Allergies in Cats: What to Know About Food, Fleas, and Environmental Triggers

If you’ve noticed your cat just can’t stop scratching, licking or sneezing, they might be dealing with allergies. Many of the most common skin and respiratory issues seen by vets are caused by allergies.

Allergies are an over-reaction of the immune system to specific triggers, and can cause a range of symptoms. These include itchy skin, weepy or irritated eyes, sneezing, and excessive licking. So what can be causing your cat’s allergies and how can you help your pet deal with them? Let’s explore some of the most common allergy triggers, how to tell what’s causing your cat’s allergies, and what you can do about them.

Quick Facts About Allergies in Cats

• Allergies in cats can cause skin irritation or itchiness, and respiratory issues.
• Common triggers include food, environmental triggers, and fleas.
• Symptoms include redness, hair loss, over-grooming, sneezing, irritated eyes, and frequent scratching.
• With veterinary care and monitoring most allergic cats can live comfortable lives.

Understanding Allergies in Cats

Allergies are caused by the immune system over-reacting to normally harmless substances. An allergic response can affect the skin, ears, eyes, and the respiratory system. Where allergic dogs tend to scratch, allergies in cats often present as grooming changes like excessive licking. The three most common causes of allergies in cats are fleas, food, and environmental triggers.

Flea Allergies (Flea Allergy Dermatitis)

How It Happens: The number 1 cause of allergies in cats is fleas. Flea allergy dermatitis (FAD) is an intensely itchy hypersensitivity reaction to flea saliva that can appear after even a single bite.

Signs of Flea Allergies: Cats suffering from FAD will have scabby, intensely itchy skin around their neck, face, belly and the base of their tail. Tiny raised crusts (miliary dermatitis) can appear on the skin. The intense itchiness may cause your cat to be restless or need to pause frequently for a fierce scratching session.

Treatment and Prevention: Flea prevention is one of the most overlooked treatments for allergies in cats, and one of the simplest ways to help. Because even a single flea bite can trigger a strong reaction, it’s important to keep your cat on a year-round, vet-approved flea preventative.

Make sure to treat any other pets in the household, too. Treating your house and washing bedding regularly help prevent recurrence. Your vet may prescribe antibiotics for secondary infections or anti-itch medications to keep cats comfortable.

Environmental Allergies (Atopy)

How It Happens: Environmental allergies are also called atopic dermatitis or atopy. Atopy is similar to hay-fever in humans, but often presents primarily as itchy skin rather than sneezing. Your cat may react seasonally or all year round. Pollen, mold, dust mites, and household chemicals like cleaners can all trigger allergies in cats.

Signs of Environmental Allergies: Cats with atopy will likely over-groom, licking and scratching excessively at their face, ears, paws, and belly. You may see hair loss or patches of red skin. Frequent head-shaking can point to itchy ears or secondary ear infections. Less common signs include sneezing or watery eyes.

Treatment and Prevention: Wiping your cat’s coat after adventures outdoors removes pollen and other irritants. Vacuum and wash bedding regularly, and consider HEPA air filters to reduce indoor dust levels.

Your vet may prescribe anti-histamines, corticosteroids, or topical treatments like medicated shampoos or creams to calm itchiness and inflammation. Omega-3 supplements may improve the skin barrier. In some cases your vet may prescribe immunotherapy shots or oral drops to keep your cat comfortable.

Food Allergies and Sensitivities

How It Happens: Food allergies happen when the immune system over-reacts to specific proteins in your cat’s food. Chicken, beef, dairy, and fish are all common triggers. While intolerances tend to cause tummy upsets, true allergies tend to cause skin issues.

Signs of Food Allergies: Food allergies in cats cause year-round symptoms including itchy skin around the face, neck, and ears. Cats may get frequent ear infections. More rarely cats may also have frequent episodes of vomiting or diarrhea. If left untreated, cats with food allergies often lose weight and have poor coats.

Treatment and Prevention: The gold standard treatment for suspected food allergies in cats is a strict diet trial using novel proteins like duck or venison, or a prescribed hydrolyzed diet. Hydrolyzed diets are diets in which proteins have been broken down into pieces tiny enough that your cat’s immune system cannot recognize and react to them. Diet trials can take 8 to 16 weeks to complete and must be strictly followed.

While over-the-counter “limited ingredient” or “hypoallergenic” foods may be tempting, they are often cross contaminated, sending you and your cat back to square one. Once your cat’s skin starts to improve, reintroducing ingredients one at a time can identify the culprits. Once you know the triggers, you can easily avoid them for your cat’s long-term comfort.

Other Causes and Contributing Factors

While fleas, food, and environmental allergies are the most common causes for allergies in cats, it’s important to remember that there may be other factors at play. Contact dermatitis can develop from contact with irritating chemicals or perfumes, while bug bites can trigger allergic reactions similar to those in humans. If left untreated, your cat’s allergies may lead to bacterial or fungal infections as bacteria and yeasts take advantage of irritated, broken skin. Stress and anxiety can worsen an allergic reaction.

How Vets Diagnose Allergies In Cats

Allergies are a common complaint, and vets often follow a step-by-step plan to identify and treat your cat’s allergies. Your visit may include:

• A complete physical exam and coat health evaluation
• Flea combing and parasite check
• Skin cytology to rule out infections
• Blood or intradermal (skin) testing to identify environmental allergies
• Food elimination or diet trials to identify food allergies

It’s important to remember that allergies often overlap, and identifying all of your cat’s triggers may take time and patience.

Treatment and Relief Options

Flea Allergies:

• Strict year-round flea prevention as prescribed by your vet.
• Treat all pets and the household environment.
• Medicated shampoos or anti-itch sprays can improve comfort.

Environmental Allergies:

• Avoid or reduce exposure whenever possible.
• Immunotherapy shots or oral medications as prescribed by your vet.
• Antihistamines, corticosteroids, or immunosuppressants like Apoquel as prescribed by your vet
• Supportive care can include omega-3 supplements or hypoallergenic diets. 

Food Allergies:

• Permanent elimination of triggering proteins.
• Use prescription hydrolyzed or novel-protein diets only.
• Monitor for secondary infections or flare-ups.

Preventing Allergy Flare-ups

Once you know the cause of your cat’s allergies, you can take some simple measures to avoid future allergy flares. Steps you can take to help:

• Regularly clean your cat’s bedding and environment.
• Employ HEPA filters, regular vacuuming, and dusting to keep dust levels low.
• Use year-round vet-approved flea preventative.
• Feed a high-quality, balanced food to keep your cat’s skin healthy.
• Schedule regular check-ups with your vet to track progress and catch any changes early. 

Final Thoughts

Allergies in cats are common and treatable with the right veterinary intervention. There are many steps you can take at home to help, and partnering with your vet early to track symptoms and responses to treatment will set your cat up for a lifetime of long-term relief.

FAQs

Author Bio

Caitlin Merrill MRCVS, BVMS, BS ASci, MLitt

Caitlin is a primary care clinician based at the University of Glasgow. She currently splits her time between clinical work, teaching, and writing. When not working she can be found hiking the moors with her mildly dramatic terrier or cuddling on the sofa with her wildly naughty cat.

Feature image: istockphoto