Food allergies in dogs


  • Just like people, dogs can be allergic to certain ingredients in their food.
  • This can cause skin and/or gastrointestinal (tummy) problems.
  • Food allergies can develop at any stage in a dog’s life, even if they have been eating the food with no issues for years.
  • A food allergy can’t be cured but, by changing your dog’s diet, the symptoms can be managed.

What is a food allergy?

Just like humans and cats, dogs can develop allergies to the ingredients in their food. A food allergy is when a dog’s immune system reacts inappropriately to one or more of the ingredients in their diet, causing skin and/or tummy issues.  

Dogs can develop allergies to any ingredients they have eaten before. They tend to be allergic to proteins (meat or dairy) — most commonly to ingredients used regularly in dog food such as beef, chicken, or lamb. Another ingredient dogs can be allergic to is wheat. Allergies in dogs can occur at any age but most commonly start when they are less than a year old.


Skin problems and gastrointestinal (tummy) problems are the most common symptoms of a food allergy in dogs. Symptoms include:

Skin symptoms

Gastrointestinal (tummy) symptoms


Your vet will want to rule out other causes of itchy skin and/or tummy issues first, and get rid of any parasites such as fleas.  

If your dog is still showing symptoms, your vet may suggest a food trial. This involves feeding a veterinary diet with special ingredients or made in a specific way so your dog does not react to it. Your vet will recommend which diet to feed.

  • You will need to feed the special diet and nothing else (other than water) for 6–12 weeks (your vet will advise you how long your dog should stay on the trial).
  • Your dog must not have any other food (including treats and dental sticks) during the trial, because if they react to it, you won’t know if the special diet has been working or not.
  • If your dog’s symptoms get better during the trial, it confirms they were reacting to something in their food.
  • If there is no improvement in your dog’s symptoms at the end of the trial, your vet may suggest other tests and treatments.

Check out our page how to conduct a food trial for more information.


If the food trial confirms that your dog has a food allergy, your vet might recommend feeding your dog their new diet for life, as long as it’s a complete food that contains all the necessary nutrients. Your dog shouldn’t have any other food or treats at all. Keep all human food and other pet food safely out of reach.

Once your dog is settled without symptoms on their special diet, you can try adding ingredients back into their food (one at a time) to try and find out what they are allergic to. If your dog doesn’t show any symptoms, this is a ‘safe’ food. Alternatively, if your dog’s symptoms come back after eating a certain food, it’s likely they are allergic to it. This will help you select a dog food that only contains safe foods. If you want to do this you should follow your vet’s advice.

Some dogs with a food allergy will also have allergies to things in the environment, this may cause atopic dermatitis (allergic skin disease). In this case, they might improve a bit on a special diet but they may need other treatments as well to help keep their skin symptoms controlled.


  • If a food allergy is well managed, your dog can live a perfectly normal life. Left untreated, food allergies can have a serious effect on your dog’s health and quality of life.
  • If your dog has a flare-up of their symptoms your vet might prescribe medication such as steroids.
  • It’s common for dogs to have more than one condition causing their symptoms, so your dog may need a combination of tests and treatments to keep them happy.
  • If you’re struggling to control your dog’s food allergy you can ask your vet to refer you to a veterinary dermatologist (a skin specialist).

When to contact your vet

You know your dog best, always contact your vet if you notice any of the symptoms above or if you think your dog may have a food allergy. There are many other conditions that can cause these symptoms as well as a food allergy and these problems can be very uncomfortable for your pet, even if they only happen some of the time.


Treatment for skin allergies can become expensive as it often involves lifelong management, so it’s important to speak openly with your vet about the cost of treatment, your finances, and what you think is right for your dog. There is sometimes more than one treatment option, so if one doesn’t work for you/your pet then your vet may be able to offer another.

Consider insuring your dog as soon as you get them, before any signs of illness start to ensure you have financial support to care for them.


Can I diagnose a food allergy with a blood test?

No, blood tests for food allergies in dogs are not accurate. The best way to diagnose a food allergy in your dog is with a food trial. 

Can I treat my dog with antihistamines?

You should never give a human drug to your dog 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

Will you give now to help people and pets in need?

As the cost of living continues to rise, vet care could be out of reach for many.

Donate to our emergency appeal now to provide vital vet care to pets in need and keep families together during this crisis.

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