Food allergies are a type of adverse food reaction involving the immune system. They most commonly cause skin problems such as itching, but some cats may also develop digestive signs such as vomiting or diarrhoea.
Food allergies can develop at any age, even if your cat has eaten the same food for years. They cannot currently be cured, but they can usually be managed successfully by identifying and avoiding the food ingredients that trigger your cat's symptoms. Some cats may also need medication to control severe flare-ups or treat secondary skin infections.
What are food allergies in cats?
A food allergy occurs when the immune system reacts abnormally to a food ingredient.
Any food ingredient can cause a reaction, but commonly reported food allergens in cats include beef, fish and chicken.
Cats can react to one or more ingredients in their diet.
A food allergy involves the immune system, whereas a food intolerance does not.
Food allergies can develop at any age, including in cats that have eaten the same food for a long time.
An elimination diet followed by reintroducing the previous diet is the most reliable way to diagnose a food allergy.
Once a food allergy has developed, it cannot currently be cured, but the symptoms can usually be controlled by avoiding the food that causes the reaction.
If you think your cat may have a food allergy, speak to a vet. Other conditions can cause similar signs, so your vet can help investigate the underlying cause and recommend an appropriate treatment plan.
Speak to our online vets if you have any questions.
Symptoms of food allergies in cats
It can be difficult to tell if your cat has a food allergy because the signs can be similar to those caused by other allergies and skin conditions. The signs may also vary in severity over time.
Food allergies most commonly cause itchy skin. You may notice:
Itching, excessive grooming, licking or chewing
Hair loss or bald patches caused by overgrooming
Red, inflamed or irritated skin
Scabs, crusts or sores caused by scratching or overgrooming
Raised skin lesions or plaques
Sores or ulcers around the head, face or neck
Swelling or inflammation around the lips or chin
Itchy ears or recurrent ear infections
Food allergies can also cause digestive signs, such as:
These signs are not specific to food allergies and can have many other causes. If your cat develops persistent itching, skin problems or digestive signs, speak to your vet for advice.
Are some cats more at risk of food allergies than others?
Food allergies can develop in cats of any age, breed or sex.
Age: Food allergies can develop at any age, including in cats that have eaten the same food for a long time.
Breed: Some studies have reported food allergies more frequently in Siamese cats and Siamese crosses, but there is not enough evidence to say that these cats are definitely at higher risk.
How are food allergies diagnosed in cats?
The diagnosis of food allergies can be challenging, and it is often a process of elimination. The signs of food allergies can be similar to those caused by other conditions, including environmental allergies (atopy) and flea allergies.
Your vet will usually start by taking a detailed history and examining your cat before recommending tests to investigate other possible causes.
Depending on your cat's signs, these may include:
A thorough physical examination
Skin scrapes, hair plucks or other skin tests to look for parasites
Skin cytology or swabs to check for bacterial or yeast infections
Blood and urine tests if an underlying health problem is suspected
Stool tests if digestive signs need further investigation
Imaging, such as X-rays or an ultrasound, if another underlying problem is suspected
Elimination diet trial
The most reliable way to diagnose a food allergy is with an elimination diet trial followed by a dietary challenge.
Your vet may recommend a hydrolysed or selected novel-protein diet for a set period. This is usually 8–12 weeks for cats with skin signs.
Your cat must eat only the recommended diet during the trial. Treats, chews and other foods must be avoided.
If your cat's signs improve, your vet may recommend reintroducing their previous diet or individual ingredients. If the signs return, this helps confirm a food allergy.
If your cat only improves partially, they may have a food allergy alongside another condition, such as an environmental or flea allergy.
For more information, see our guide to elimination diet trials in cats.
Vet treatment for food allergies in cats
Treatment may involve a combination of approaches to control your cat's symptoms and manage any related problems.
Your vet may recommend:
A suitable diet: if a food allergy has been confirmed, avoiding the ingredients that trigger your cat's symptoms is the main treatment. Your vet can help you choose a suitable long-term diet.
Anti-itch medication: may be prescribed to control severe itching or flare-ups while the underlying problem is being managed.
Parasite control: appropriate treatment may be recommended for parasites, like fleas, if they are part of your cat's skin problems.
Treatment for other allergies: if your cat also has an environmental or flea allergy, your vet may recommend additional treatment to control these triggers.
Once a food allergy is confirmed and the trigger is avoided, many cats can be managed successfully with an appropriate diet. Some cats may still need medication to control flare-ups or treat secondary skin or ear infections.
If your cat's symptoms are severe, difficult to control or do not respond to treatment, your vet may refer you to a veterinary dermatologist for further investigation and management.
How to look after a cat with food allergies at home
The most important part of managing a food allergy at home is avoiding the ingredients that trigger your cat's symptoms.
Diet
Feed a complete and balanced diet: Your vet can recommend a suitable long-term diet that avoids your cat's known food triggers. This may be a hydrolysed-protein diet or an appropriate novel-protein diet.
Be careful with treats and extras: Check treats, chews, supplements and flavoured medications with your vet, as they may contain ingredients that could trigger your cat's symptoms.
Home-prepared diets: These can sometimes be used, but should be formulated with advice from a veterinary nutritionist to make sure they provide all the nutrients your cat needs.
Skin and ears
Ear cleaners: Some cats may benefit from regular ear cleaning, but the appropriate product and frequency will depend on their individual needs. Over-cleaning can irritate the ears.
Skin products: Your vet may recommend medicated shampoos, mousses or other topical treatments to help manage irritated skin or secondary infections.
Skin supplements: Supplements containing omega-3 fatty acids may be recommended to support skin health.
Digestive signs
If your cat has soft stools, diarrhoea or other digestive problems, speak to your vet. They may recommend dietary changes or other treatment. Probiotics may be appropriate for some cats.
Speak to your vet before introducing new supplements, ear cleaners or other treatments, as these may not be appropriate for every cat.
Our Joii vets are available 24 hours a day for advice.
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Tips on how to prevent food allergies in cats
Unfortunately, there is no currently proven way to prevent food allergies in cats.
If your cat suffers from persistent itchy skin, recurrent ear problems, or digestive issues, speak to a vet as soon as possible to investigate and treat the underlying problem.
Is my family at risk of catching food allergies?
Food allergies are not contagious. Your cat cannot pass a food allergy to another animal or to people in your household.
When you should be worried about food allergies in cats
Seek urgent veterinary care if:
Your cat is severely itchy, particularly if they are causing damage to their skin.
Your cat is losing weight or has a reduced appetite.
Your cat has severe or repeated vomiting or diarrhoea, particularly if there is blood.
Your cat has persistent skin or digestive problems that are not improving.
Speak to a Joii vet if:
You think your cat may have a food allergy and would like advice on the next steps.
You would like advice about starting an elimination diet trial.
Your cat has mild itching, ear problems or digestive signs and is otherwise well.
You have questions about your cat's diet or nutritional needs.
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