There are actually many things cats can be allergic to, including fleas, foods and pollen. When an allergic cat comes into contact with the thing it is allergic to, its immune system overreacts and can cause things like persistent itching or skin sores.

In this guide, we focus on allergies in cats, how to spot an allergic reaction, common allergens, and what you should do if your cat is having a reaction.

What Are Cats Allergic To?

An allergy is an overreaction of the immune system to a substance that might be harmless to most cats. Cats can be allergic to several things, including:

• Fleas
• Certain foods
• Pollen
• Mould
• Dust mites
• Some medications
• Household chemicals
• Cat litter dust or fragrances

This is a guide that is specifically focused on allergies in cats — not humans being allergic to cats. We talk about signs of an allergic reaction like persistent itching, skin sores, vomiting, diarrhoea, coughing, wheezing or breathing difficulty. These things should all be assessed by a vet if they happen.

Note that some cats have more than one allergy at once, so diagnosis is not always straightforward.

What Are the Most Common Allergies in Cats?

There are several allergies that are quite common in cats. Flea allergy dermatitis is one, as are various food allergies and environmental allergies (also called atopy or atopic dermatitis). Other common ones include contact allergies, allergic reactions to medicines, and airway allergies.

The symptoms of these things can sometimes overlap, so it is not a good idea to try to guess the cause based on the symptoms alone. Many allergic reactions in cats show through the skin, even when the allergen is food or something in the environment.

A cat that is scratching, overgrooming or losing fur may not be "just itchy" — it could be reacting to an allergen, parasites, infection or another skin condition.

Flea Allergies in Cats

Flea allergy dermatitis is caused by an allergic reaction to flea saliva. A particularly sensitive cat might have an intense reaction even if only a few fleas are present. Sometimes fleas go unnoticed because they hide in soft furnishings, carpets and bedding rather than on the cat.

Symptoms that a cat is having an allergic reaction to flea bites include:

• Intense itching
• Scratching and overgrooming
• Hair loss
• Red or inflamed skin
• Scabs, especially around the head, neck, lower back or base of the tail
• Secondary skin infection from repeated scratching or licking

You can minimise the risk of this by using regular vet-recommended flea prevention for every cat in your home. If fleas are suspected, treat every cat in the household and wash bedding and vacuum carpets, rugs, sofas and soft furnishings.

Don't make the mistake of assuming indoor cats are safe from fleas. They can enter the home on clothing, other pets or visiting animals.

Food Allergies in Cats

Food allergies happen when the immune system reacts to a certain ingredient in the diet — most often a protein. The most commonly reported food allergens for cats include beef, fish, chicken and dairy.

Grains are often blamed, but animal proteins are actually more commonly implicated in feline food allergies. The symptoms to look out for include:

• Constant, non-seasonal itching
• Overgrooming
• Hair loss
• Red or inflamed skin
• Ear or skin infections
• Vomiting
• Diarrhoea
• Weight loss
• Reduced appetite

Other possible but less common triggers for cat food allergies include lamb, rabbit, egg, wheat, barley, corn, preservatives, additives or artificial colourings.

Around 10–15% of cats with food allergies may show gastrointestinal signs like vomiting and diarrhoea. A cat can develop an allergy at any age, even after eating the same food for years. Minimise risk by avoiding swapping foods randomly without veterinary advice and steering clear of lots of different treats, supplements or table scraps.

A vet may recommend an elimination diet using a novel protein or hydrolysed diet. During a food trial, the cat must eat only the recommended diet — no treats, flavoured medicines, scraps or alternative foods.

Environmental Allergies in Cats

Environmental allergies can be seasonal or they can happen all year round. The most common environmental allergen is pollen, but cats can also be allergic to:

• Grass
• Trees
• Mould
• Mildew
• Dust mites
• Storage mites
• Yeast
• Human or animal dander

Seasonality is important because pollen and grass allergies might flare up in spring, while dust mites and mould can cause problems throughout the year.

Watch for things like itchy skin, overgrooming, rubbing against furniture, skin redness, fur loss and scabs, sneezing, or coughing and wheezing. Reduce risk by keeping bedding clean and dry, vacuuming regularly, avoiding smoke near pets and using good ventilation (where safe). Speak to a vet if symptoms are recurring or seasonal.

Household Products and Contact Allergies

Contact allergies happen when a cat's skin reacts to something it touches. There are various contact triggers that cats react to, but common ones include:

• Cleaning sprays
• Laundry detergents
• Carpet fresheners
• Air fresheners
• Scented candles or fragrance diffusers
• Shampoos
• Flea collars or topical products
• Plastic food and water bowls
• Wool or certain bedding materials

You should look out for symptoms like itching or redness where the allergen touches the skin, paw irritation, chin irritation from bowls, or belly and leg irritation from bedding and carpets.

Reduce the risk by always using pet-safe cleaning products and rinsing cleaned surfaces thoroughly. Avoid using strong fragrances around cats and switch to ceramic, glass or stainless-steel bowls for food and water. Wash bedding with a mild, fragrance-free detergent.

Can Cats Be Allergic to Cat Litter?

Cats are not usually allergic to litter in the same way that they might be allergic to fleas or food. However, in some cases, cats can be irritated by dust, fragrances or chemicals in certain cat litters.

Dusty litter can be a concern for owners of cats with respiratory sensitivity or asthma-like symptoms. Here are some possible signs that litter may be irritating your cat:

• Sneezing after using the tray
• Coughing near the tray
• Watery eyes
• Avoiding the litter tray
• Scratching around the paws
• Overgrooming feet or legs

We recommend you choose a low-dust litter and always keep the litter tray clean. Avoid heavily scented litter and position the tray in a calm and well-ventilated area. Litter Sense cat litter is made from silica crystals, so it is mostly dust-free, and it offers the added benefit of changing colour if your cat's urine is abnormal, potentially alerting you to a sign of ill health.

Signs Your Cat May Be Having an Allergic Reaction

The following table breaks down potential symptoms into common signs in the skin and coat, and digestive and respiratory symptoms.

Skin and coat symptoms	Digestive and respiratory symptoms
Excessive scratching	Vomiting
Overgrooming or licking	Diarrhoea
Biting or chewing fur	Flatulence
Hair loss	Weight loss
Red skin	Reduced appetite
Scabs or crusts	Sneezing
Skin rash	Runny eyes or nose
Ear infections	Coughing or wheezing
Swollen or sensitive paws	Open-mouth breathing
Poor coat condition	Breathlessness or collapse in severe cases

If you notice open-mouth breathing, severe breathing difficulty, facial swelling, collapse or signs of anaphylaxis, these are all signs of an emergency. You must seek urgent veterinary care.

How Are Cat Allergies Diagnosed?

Diagnosis may take a little bit of time because allergies often resemble other conditions. Things like parasites, infections, wounds or gastrointestinal disease can all present in similar ways to allergic reactions. This can delay the diagnosis.

When trying to determine the cause of symptoms, a vet may use:

• Physical examination
• Flea combing and flea dirt checks
• Skin cytology
• Skin scraping or biopsy if needed
• Blood tests for some environmental allergies
• Intradermal skin testing
• Elimination diet trial for suspected food allergies
• Chest X-rays or respiratory checks if there is coughing or wheezing

Food allergy blood tests are not usually the preferred route. Vets find that elimination trials tend to be more successful. If you notice symptoms, never attempt to give human antihistamines, painkillers, steroids or supplements without advice from your vet.

How to Reduce the Risk of Allergic Reactions in Cats

As the owner, you can take responsibility for minimising the risk of an allergic reaction in cats, and knowing what cats are allergic to is a good starting point. This enables you to carry out best practices for prevention, such as:

• Keeping up with regular flea prevention
• Feeding a consistent, complete and balanced diet
• Introducing new foods gradually and avoiding constantly changing proteins without a reason
• Keeping a diary of symptoms, food, treats, litter, cleaning products and seasonal changes
• Using low-dust, unscented or minimally scented litter if respiratory irritation is a concern
• Avoiding smoke, aerosols, strong perfumes and heavily fragranced home products
• Washing bedding regularly
• Vacuuming and dusting areas where the cat sleeps
• Using ceramic or stainless-steel bowls rather than plastic if contact irritation is suspected
• Speaking to a vet before changing flea treatments, diets or medicines

Not all allergies can be prevented, as they relate to things in the natural environment. In these cases, once triggers are identified, you can reduce flare-ups by keeping your cat away from the thing it is allergic to. Though allergies are not curable, they are usually very manageable.

When Should You Speak to a Vet?

We recommend that you contact a vet if you notice your cat's itching lasts more than a few days. If the cat scratches so much that the skin breaks, or you notice scabs, sores or bald patches, these should also be checked by a vet.

Persistent vomiting or diarrhoea should be assessed by a vet as well. If you notice your cat is losing weight, or is coughing and wheezing regularly, this could be about more than just an allergic reaction, so contact your vet for an appointment.

There are certain symptoms that should be treated as emergencies. Get your cat seen immediately if you notice:

• Open-mouth breathing
• Severe breathing difficulty
• Blue or pale gums
• Facial swelling
• Collapse
• Sudden severe weakness
• Suspected anaphylaxis

If you notice allergic reactions and suspect food is the cause, it is best to seek a proper diagnosis rather than repeatedly changing food. The same goes for litter or household products. Guesswork is not a reliable way to make the necessary changes — let your vet advise you.

Frequently Asked Questions About What Cats Are Allergic To

What is the most common allergy in cats?

Flea allergies, food allergies and environmental allergies are all among the most commonly diagnosed categories.

Can indoor cats have allergies?

Yes, they can. Indoor cats can react to things like fleas, dust mites, mould, food ingredients, cleaning products, litter dust and other household triggers.

What foods are cats most often allergic to?

Commonly reported food allergens include beef, fish, chicken and dairy. But any ingredient can potentially cause a reaction, so it is important to get a diagnosis.

Can cats be allergic to cat litter?

Some cats can be irritated by dusty, scented or chemically treated litter. This is particularly common if they have respiratory sensitivity.

Can cat allergies go away?

Many allergies are long-term, but symptoms can often be managed with veterinary diagnosis, trigger avoidance and the right treatment plan.

Should I change my cat's food if I suspect an allergy?

This is not recommended without a plan. We strongly urge you to speak to a vet about an elimination diet rather than simply making repeated random diet changes.