Food allergy in dogs – signs and what to do

Updated 2026-09-30 · 1 sources

Based on: PDSA

Book a vet visit

Book a vet appointment if you think your dog has this – a vet needs to confirm it and plan the treatment. A food allergy is a reaction to certain ingredients in your dog’s food that can cause skin or tummy problems.

What to do now

What you can do now

Contact your vet.
Note when it started, how often it happens and what else you see.
Take a photo or short video to show the vet.
Keep fresh water available.
Let your dog rest somewhere calm.

Don't

Do not give any human medicine.
Do not wait if it gets worse.

What it is

Dogs can be allergic to certain ingredients in their food, which can cause skin and/or gastrointestinal problems.^[1] Food allergies can develop at any stage in a dog’s life, even after years of eating the food without problems.^[1]

Signs

Itchy skin, including itchy ears
A rash or red, sore skin, especially on the feet, ears, face, chin, tummy and groin
Pink or brown saliva staining on the coat
Vomiting
Diarrhoea
A sore tummy
Excessive wind
Itchiness, especially on the head or neck, lasting all year round
Fur loss because of overgrooming
A bumpy skin rash

Causes and risk factors

Certain ingredients in food

How vets treat it

A vet may recommend a diet change.
If a food trial confirms the allergy, a vet might recommend feeding a complete new diet for life, with no other food or treats.

What the experts say

“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.”
— PDSA [1]

If your pet is struggling to breathe, has collapsed, is having a seizure or can't stand up: go to the nearest vet now.

Not sure how serious it is?

OkPaw asks a few quick questions about your pet and tells you in 30 seconds whether it can wait. Free on Google Play for Android.

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Common questions

What signs can a food allergy cause in dogs?

Signs can include itchy skin, a rash or sore skin, saliva staining, vomiting, diarrhoea, a sore tummy and excessive wind.^[1]

Can a dog develop a food allergy after eating the same food for years?

Yes. Food allergies can develop at any stage in a dog’s life, even if they have eaten the food without problems for years.^[1]

How might a vet treat a food allergy?

A vet may recommend a diet change; if a food trial confirms the allergy, they might recommend a complete new diet for life with no other food or treats.^[1]

Sources

PDSA

How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages

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