The best food for cats with allergies

An allergy is when a cat’s immune system overreacts to something in their environment. Cats can be allergic to many substances (known as allergens) in the environment and in their food. While it’s understandable to blame a cat’s food for symptoms like itchiness and hair loss, food allergies are uncommon compared to other causes of itchy skin, rashes, and hair loss in cats, so it’s best to talk to a veterinarian if you suspect your cat has an allergy rather than simply changing their food.

There is no single “best” diet for cats with allergies. The best diet depends on what your cat is allergic to and on any other underlying health issues they may have. If you think your cat may have food allergies, it’s important to know:

• Common ingredients that cats can be allergic to
• What food is best for a cat with allergies
• How vets diagnose and treat food allergies in cats

If your cat has a food allergy, your vet may recommend a special therapeutic diet with novel or hydrolyzed proteins, a carefully chosen commercial food available at a grocery or pet store, or a home-prepared diet formulated under the guidance of a veterinary nutritionist.

Diagnosing food allergies typically involves a very controlled, limited-ingredient elimination diet carried out over an extended period of time. Working with an online veterinarian can make the process easier by helping you track and interpret your cat’s symptoms between in-clinic visits, offering guidance on next steps, and keeping your care plan on track during what can be a long and sometimes complicated process.

A food allergy is an immune system response to specific proteins within the diet. The most common ingredients that trigger food allergies in cats are animal proteins, such as beef, pork, chicken, fish, or dairy products. Less commonly, food allergies may be triggered by eggs, lamb, pork, or rabbit. While grains are sometimes blamed for allergies, true grain allergies in cats are rare. Since allergies are triggered by a specific ingredient in the food, changing the brand or flavour of the food won’t be effective unless the new diet is free of the problematic ingredient.

Similar to inhaled or contact allergies, food allergies primarily cause skin symptoms, such as:

• Itchy skin and excessive scratching
• Hair loss, especially around the face and neck
• Skin inflammation, redness, or rash
• Small fluid-filled bumps on the skin
• Crusty or scabbed skin
• Chronic skin or ear infections

Less commonly, some cats with food allergies may also develop stomach upset, causing clinical signs like:

• Vomiting
• Diarrhea
• Excessive flatulence

Food allergies are uncommon in cats. Poor skin health is more often caused by other types of allergies, bacterial or fungal infections, external parasites, or thyroid disease. Food allergies are also not a likely explanation for stomach upset, since there are other conditions with similar symptoms that are far more common.

There is no single “best” cat food for cats with food allergies, since different cats are allergic to different ingredients. If your cat has food allergies, the best food is a well-balanced diet that doesn’t contain the ingredient they’re allergic to.

During the diagnostic process, ingredients that trigger a cat’s food allergies are identified, making it possible to eventually select a diet that avoids those ingredients while still meeting all nutritional needs. These diets are generally available as both canned and dry and can take several forms:

• Regular commercial diets that avoid the allergen: Some pets improve simply by switching to a commercial food that doesn’t contain the specific ingredient triggering the allergy (for example, changing from a chicken- to a fish-based diet).
• Limited-ingredient diets: These contain only one protein and one carbohydrate source that the cat hasn’t been exposed to before (such as duck and potato, or venison and pea) to reduce the number of potential allergens.
• Hydrolyzed protein diets: In these therapeutic diets, proteins are broken down into very small fragments so the immune system no longer recognizes them as allergens. Hydrolyzed diets are considered the most reliable option for diagnosing and managing food allergies, especially when the trigger is unknown.

In some cases, an owner may wish to try a home-prepared diet, and the best way to develop one that’s complete and balanced is to work with a board-certified veterinary nutritionist. Improperly formulated homemade diets can lead to nutritional deficiencies or worsen the pet’s health over time.

Can diet help other types of allergies in cats?

Diet changes are primarily useful for cats whose allergies are triggered by food ingredients. If your cat has more common allergies, such as flea or environmental allergies, changing food alone will not resolve the problem. In those cases, other targeted treatments are needed to help your cat feel better.

However, diet and dietary supplements can play a role when used with other treatment methods. For example, diets and supplements that contain omega-3 fatty acids may help support skin as it heals from the damage caused by overscratching and infections.

Use of the term hypoallergenic on pet food labels isn’t strictly regulated, so food found at a pet or grocery store may not be effective for diagnosing or managing a true food allergy. Many over-the-counter diets marketed as hypoallergenic still contain common ingredients that can trigger allergies or are produced on equipment that allows for cross-contamination.

Veterinary prescription hypoallergenic diets are manufactured under controlled conditions and use precisely defined ingredients that are unlikely to trigger an allergic response. For cats with suspected food allergies, it’s best to get guidance from a veterinarian for diagnostic food trials or long-term feeding plans.

When a cat develops itchy skin or a rash, many pet owners think, “It can’t be allergies because nothing has changed.” In reality, allergies don’t develop from something new; they happen after repeated exposure to a particular allergen over time.

With food allergies, the immune system becomes sensitized and starts overreacting to a food protein the cat has eaten for months or even years. As a result, wondering about what’s new in your cat’s diet isn’t the pathway to diagnosing a food allergy. Instead, vets use dietary trials to diagnose food allergies.

The overall goal of a dietary trial is to strictly control what a cat eats and watch for improvement. In a dietary trial, it’s important to ensure your cat only consumes a very limited list of ingredients that:

• Your cat hasn’t had before
• Are unrecognizable to your cat's immune system
• Are not common triggers for allergies

Treats, flavored medications, and table scraps can contain ingredients you are trying to avoid, so they must also be strictly controlled.

It usually takes six to 12 weeks for old allergenic proteins to leave the body and for the skin to heal. Some cats start to feel better after a few weeks, but most don’t show clear results until after two months of strict feeding on the limited diet.

If a cat seems to improve right away, it’s often because of other factors, such as starting parasite control, stopping treats, treating infections, giving medications at the same time, or something coincidental like a change in the pollen count rather than the diet change itself.

To confirm a true food allergy, veterinarians recommend a challenge test once the cat improves. This means reintroducing the old diet to see if symptoms return. If they do, it confirms the food allergy diagnosis and guides which ingredients to avoid long-term.

When it’s determined that the cat’s symptoms are caused by a food ingredient, other ingredients can be slowly reintroduced. Ingredients should be introduced one at a time so that if symptoms return, the allergen can be more easily identified and avoided in the future.

Is a food trial the only way to diagnose feline allergies?

“Food trials take a long time and require strict control over what your cat eats, plus interpreting them isn’t always straightforward,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “Other tests diagnosing food allergies in cats do exist, but they are not recommended in standard veterinary guidelines.” Other available tests include:

• Serum allergy tests (blood tests): Measure antibodies (IgE or IgG) thought to be directed at food proteins
• Intradermal skin testing: Reliable for environmental allergy testing and sometimes adapted for foods
• Hair and saliva tests, often marketed directly to pet owners: Not validated in veterinary medicine and considered unreliable

These tests are not recommended for diagnosing food allergy due to poor accuracy and reliability. Multiple studies show blood and saliva tests for food allergy in cats and dogs have low sensitivity and specificity. They may produce false positives (showing reactions where none exist) and false negatives (missing true allergies). These testing methods also lack evidence to support that they work, and research shows that they cannot reliably diagnose food allergies in cats. The elimination diet trial is the gold standard for diagnosing food allergies in pets.

If you believe your cat has food allergies, it’s best to talk to a veterinarian. Itchiness, hair loss, stomach upset, and other symptoms associated with food allergies are more common with other health issues, both allergic and non-allergic. Confirming whether a cat’s symptoms are due to an allergy to their food or another cause requires a structured process, and working with a veterinary professional is the best way to get clear answers. It’s important to closely follow your vet’s instructions regarding food trials to make sure results are as accurate as possible. This means avoiding treats, table scraps, and other foods not pre-approved by your veterinarian during the trial period.

How an online vet can help

Food trials for diagnosing allergies in cats often take months, and adjustments are usually needed along the way. An online veterinarian can make this process easier by providing ongoing support to cat owners without the frequent in-clinic visits. Through virtual check-ins, online vets can review your cat’s progress, help interpret changes in symptoms, and guide you on what steps to take next.

Online vets can also prepare you for what to expect during the diagnostic process, answer questions between in-person visits, and offer practical advice when challenges come up, such as accidental exposures, difficulty with diet acceptance, or unclear responses. This ongoing partnership helps keep the trial on track, reduces stress for both you and your cat, and ensures you have expert input throughout the process.

What can I feed my cat to help with food allergies?

There is no single cat food that’s best for cats with allergies. Cats with food allergies have an inappropriate immune system response to a protein in their food, so the best food will be a nutritionally balanced diet that does not contain the protein source that’s causing the symptoms. Be cautious with over-the-counter foods labeled “hypoallergenic.” This term isn’t regulated and doesn’t guarantee the food is free from common allergens. It’s best to work with a veterinarian to determine what’s causing the symptoms and, if it is a food allergy, which ingredient(s) to avoid.

Can cats get over food allergies?

Allergies are typically a lifelong condition in cats, but they can often be managed well enough to keep the cat comfortable and their skin and coat looking good. Food allergies can be managed by choosing a cat food that doesn’t contain the ingredient(s) a cat is allergic to and avoiding treats, flavored medications, and table scraps that contain the ingredient. When the cat no longer comes into contact with the ingredient, the allergy symptoms will stop.

Which foods do vets recommend for cats with allergies?

There isn’t a single specific food that vets recommend for cats with allergies. The best cat food for an allergic cat is one that is nutritionally balanced, does not contain the animal protein sources that cause the symptoms, and supports any other health issues the cat may have. This may be a special hypoallergenic cat food, a veterinary-recommended commercially available diet, or a home-cooked diet created with the help of a veterinary nutritionist.

Disclaimer: This article, its content, and its related references do not constitute veterinary advice and should not be considered a substitute for veterinary care. If your pet is showing any symptoms that could indicate a medical emergency, please seek immediate emergency care.