Food allergy in cats


  • Just like us, cats can develop allergies to certain ingredients in their food.
  • Food allergies in cats tend to cause skin reactions and/or gastrointestinal (tummy) problems.
  • A food allergy can develop at any point in a cat’s life, even if they have been eating the food with no issues for years.
  • Fortunately, symptoms can be improved and sometimes even eliminated if you feed your cat a diet that suits them.

What is a food allergy?

Just like humans and dogs, it’s possible for cats to develop food allergies — often to things they have eaten for years with no problem. Food allergies occur if the immune system mistakes a food for something dangerous, and reacts inappropriately, causing skin and/or stomach issues. They can occur at any age, but usually start between four to five years of age.


Food allergies normally cause skin issues (most common) and/or tummy problems in cats. Often cats are allergic to more than one thing — each causing different symptoms. Anaphylaxis (a severe allergic reaction) can happen, but is extremely rare.  Symptoms include:

Skin symptoms

Gastrointestinal (tummy) symptoms


It can be very difficult to diagnose a food allergy in cats. Your vet will want to rule out other causes of itchy skin and/or tummy issues first. Your vet will also want to treat any skin infections caused by your cat scratching and get rid of any parasites such as fleas first.

If your cat is still showing symptoms, your vet may recommend a food trial. This will last at least six weeks for skin issues, or two weeks for tummy issues and involves feeding only a specific low-allergy food with none of your cat’s normal food or treats. Your vet will help you choose the food that is best for you and your cat. If you have multiple cats you may want to consider a microchip cat feeder or feeding them in separate rooms during the food trial. Check out our video below for more information.

If your cat’s symptoms improve during the trial it confirms they were reacting to something in their food. If your cat’s symptoms don’t improve, and you’re sure they didn’t eat anything else during their food trial, speak to your vet. Your cat may be allergic to something in their environment.


If the food trial confirms that your cat has a food allergy, your vet will probably recommend keeping your cat on their new food for life, as long as it’s a complete food that contains all the necessary nutrients. Your cat shouldn’t have any other food at all. If any friends or neighbours feed your cat, they will also need some of their special food to give them. Keep all human food and other pet food safely out of reach.

Once your cat’s symptoms have cleared up, if necessary you can try reintroducing one ingredient at a time to see if your cat reacts. However, this isn’t necessary if you and your cat are happy with their new diet. If you want to do this, you should follow your vet’s advice.


  • Cats with food allergies can live a normal life without symptoms if they eat a diet that suits them.
  • However, identifying problem foods and keeping your cat away from them can be tricky.
  • If your cat has a flare-up of their symptoms, your vet might prescribe them medication such as steroids.
  • If you are struggling to control your cat’s food allergy, you can ask your vet to refer you to a veterinary dermatologist (a skin issue specialist).

When to contact your vet

Contact your vet if your cat is showing any of the symptoms above, especially if they are itchy all the time with no obvious explanation (such as fleas). Skin problems left without treatment often get worse quickly.

You know your cat best, always contact your vet if you’re concerned.


Diagnosing and managing a skin allergy can become very expensive, especially if they need lifelong treatment. It’s important to speak openly to your vet about your finances, the cost of treatment, as well as what you think is right for your cat.

Consider insuring your cat as soon as you get them, before any signs of illness start. This will ensure you have all the support you need to care for them.


Can I diagnose a food allergy with a blood test?

No, blood tests for food allergies in cats are not accurate. The only way to diagnose a food allergy in your cat is with a food trial. 

Can I treat my cat with antihistamines?

You should never give a human drug to your cat unless your vet has told you to. Antihistamines can be used to help reduce symptoms of a food allergy at the beginning of a food trial, but are unlikely to work alone.

Published: June 2023

Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.