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Food Allergies in Cats

Food allergies in cats can occur at any point. A food allergy is an immune system response and is usually caused by a certain ingredient, typically a protein source, that the body mistakenly identifies as a foreign body.

The body creates an inflammatory response to fight what it believes is a foreign body, and this results in an allergic reaction.
Illustrations of a cat with a red cat food bowl

Food Allergies

Food allergies are caused by an adverse reaction to an ingredient in your cat's diet.

Environmental Allergies

Environmental allergies, also known as atopic allergies, are an inflammatory response to allergens in your cat's environment, such as dust.

Brown cat standing up and eating from a silver cat food bowl

Speak to Your Veterinarian


As it can be tricky to differentiate between the signs of food and environmental allergies, it's important to speak to your veterinarian to get a proper diagnosis.

Learn more about the differences between the two types of allergies in our article, food allergies vs atopic dermatitis in cats.


Illustration of two cats sitting down

What Is likely To Cause a Food Allergy?

Cats can develop a food allergy to any ingredient, at any time in their life.

An allergic reaction will arise when their immune system mistakenly believes an ingredient, such as a protein, is something foreign and therefore harmful.

How Might a Food Allergy Affect Your Cat?

A dermatologic reaction to a food allergy is common; meaning issues relating to the skin and coat may arise from a food allergy.

Common signs of food allergies in cats include:

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Recurring skin infections

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Redness of the skin

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Gastrointestinal upset

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Ear inflammation

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Hair loss

Keep reading to understand more about the signs you should look out for and where these signs are likely to occur on your cat's body.

Signs of a food allergy
Illustration of a vet and cat

Supporting Your Cat if They're Suffering From a Food Allergy

If you believe your cat is showing signs of a food allergy, always speak to your veterinarian before taking action.

Once your veterinarian has confirmed it is a food allergy (most likely through an elimination diet trial) they will advise the most suitable management options for your cat.

Although a food allergy is a serious condition, if the signs are noticed early it can be properly managed so your cat can continue to live a healthy life.

Veterinarian holding a cat

Tailored Diets


If a change in diet is recommended, there are two different options your veterinarian may suggest; a hydrolyzed protein diet or a novel protein diet.

Learn more about tailored diets for food allergies in cats below. 

Nutrition and food allergies


Understand Cat Food Allergies

Short on time? Boost your knowledge of food allergies in cats with these short frequently asked questions.

A food allergy occurs when a cat’s immune system mistakes something in food for a hostile invader. Food intolerance is a bodily response to certain foods but it doesn’t involve the immune system. Your vet can perform tests to identify these conditions.

Dermatology diets are designed to support adult cats with skin conditions. They contain a blend of nutrients to aid healthy skin cell generation, and may help ease the signs of skin inflammation caused by an allergy or a health condition. Your vet can recommend a dermatology diet that’s right for your cat.

A cat’s immune system is more likely to react to large intact proteins. This is why the protein molecules in hydrolyzed diets are cut into many tiny pieces to lessen the chances of an allergic response. Novel or select protein diets aim to limit the chances of a reaction by using sources of protein that may be less familiar to a cat’s immune system, such as duck or venison.

The most common cat food allergies are beef, fish, and chicken1 so a diet containing a different source of protein may be beneficial. However, allergies are caused by a variety of substances and can cause serious health issues, so you should always speak to your vet if you think your cat has an allergy. Your vet will help you identify the allergen and recommend appropriate nutrition for your cat – such as a hydrolyzed or novel protein diet.

Signs of cat food allergies are similar to other health conditions and allergies caused by pollen, dust, and fleas. A vet will usually conduct a physical exam first to see if the signs are a result of fleas or other topical skin conditions. If they suspect food allergies, then they will likely recommend an elimination diet trial. The trial involves feeding a cat a hydrolyzed protein diet for 8-12 weeks, after which, the vet will slowly reintroduce suspected allergens to see if they trigger a response.

Cats with food allergies often have itchy and inflamed skin and they may develop gastrointestinal issues, such as vomiting and diarrhea. Other possible signs include skin infections, rashes, and hair loss. Because these signs are indistinguishable from other allergies and share similarities with other health issues, we’d always recommend scheduling an appointment with your vet if you suspect your cat has an allergy.

There are several reasons your cat may have itchy skin, including allergies and parasites. Your vet will help determine the cause and may recommend an appropriate diet as part of their treatment plan. For example, if your cat has a food allergy, they may suggest a hydrolyzed or novel protein diet to promote healthy skin.

Cats with skin issues may need special nutritional support, so your vet is the best person to speak to for guidance about their diet. They’ll suggest the best food for your cat, based on their breed, age, health condition, and medical needs. Some of the options they recommend may include a hydrolyzed or novel protein diet.

If your vet rules out a food allergy as the cause of your cat’s signs, they’ll need to investigate other causes, such as an environmental allergy. The skin irritation patterns associated with allergies are common to other health issues, so these will need to be investigated too.

Ask Your Veterinarian About These Products for Cats

Ask your veterinarian if any of the following products from the Royal Canin Dermatology range are suitable.

Hydrolyzed Protein HP Dry Cat Food

Available through veterinarians, our Hydrolyzed Protein HP Dry helps support skin health and healthy digestion in pets who may have sensitivities to common proteins found in pet foods. This diet contains essential nutrients to support the skin barrier.

Hydrolyzed Protein Feline Treats

Hydrolyzed Protein Feline Treats are made with hydrolyzed soy proteins for occasional use as a treat for cats who may have food sensitivities.