Food allergy in cats – signs and vet treatment

Updated 2026-09-30 · 1 sources

Based on: PDSA

Book a vet visit

Book a vet appointment if you think your cat has this – a vet needs to confirm it and plan the treatment. A food allergy is an allergy to certain ingredients in your cat’s food.

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 cat rest somewhere calm

Don't

Do not give your cat any human medicine
Do not wait if it gets worse

What it is

Food allergies in cats tend to cause skin reactions and/or gastrointestinal (tummy) problems.^[1] A food trial can confirm whether your cat has a food allergy.^[1]

Signs

Itchiness, especially on the head or neck, lasting all year round
Fur loss because of overgrooming
A bumpy skin rash
A skin infection caused by scratching
Diarrhoea, usually mild
Vomiting
Weight loss

Causes and risk factors

Certain ingredients in food

How a vet finds out

A vet may use a food trial to confirm the food allergy

How vets treat it

If the food trial confirms the allergy, a vet will probably recommend keeping your cat on the new food for life
The new food should be complete and contain all the necessary nutrients
Your cat should not have any other food

What the experts say

“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.”
— 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 food allergy cause in cats?

Signs can include itchiness, fur loss from overgrooming, a bumpy skin rash, a skin infection from scratching, diarrhoea, vomiting and weight loss.^[1]

How can a vet confirm a food allergy?

A food trial can confirm whether your cat has a food allergy.^[1]

What may happen after a food allergy is confirmed?

A vet will probably recommend keeping your cat on the new food for life, as long as it is a complete food containing all the necessary nutrients, and your cat should not have any other food.^[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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