My Cat Is Allergic to Fleas: What Do I Do?

You might not have guessed it, but cats can get fleas just as frequently as dogs do. In fact, flea bite hypersensitivity, or flea allergy dermatitis in cats, is the most common skin disease. There is even a specific species of flea called the cat flea, which is actually the flea that is most often responsible for the allergies found in dogs as well.

If a cat is allergic to fleas, he will scratch, bite, and lick at the bites that may be all over his body, which can be quite a bothersome condition, making life very uncomfortable for your furry feline friend. When cats are allergic, this incessant scratching and licking can lead to skin inflammation in cats, hair loss, and sores that make your pet more susceptible to developing secondary infections.

In order to provide your cat with some relief, you will have to take steps to remove the fleas from your cat’s environment, which may be easier said than done. This post is going to look into how to relieve the symptoms of a cat allergic to fleas and arm you with the right information you need to fight your cat’s flea infestation. You’ll know what signs to look for as well as how to properly treat a flea allergy so you and your cat can go back to enjoying your lives together.

What is a Flea Allergy in Cats?

A flea allergy, or flea allergy dermatitis, occurs when a cat has an allergic reaction to a flea bite on his skin. Dogs and cats can develop allergies to fleas, but the level of their symptoms will vary from pet to pet based on their sensitivity.

The allergic reaction is triggered by certain proteins in the flea’s saliva. The saliva is injected into the cat when bitten by the flea. It may only take a couple of bites to make a break out in symptoms. Some cats are so allergic that it may take just a single bite to cause an intense reaction.

Flea allergies do not pose a serious threat to your cat, but it can make life very uncomfortable if left untreated, leading to skin issues and raising the potential to develop secondary bacterial or fungal infections. Cats usually develop flea allergies when they are still young, but allergies can develop at any age.

As mentioned, the culprit for a flea allergy is believed to be the saliva in the flea that is excreted when the insect bites the animal. While the biting and saliva are what causes irritation to the cat’s skin, the real issue lies in if the flea is able to lay eggs, as this can lead to a much bigger issue if an infestation is allowed to develop.

Fleas will latch on to a cat as adults and lay eggs, which develop into larva and pupa. As this life cycle continues, the infestation on the cat will grow, causing more and more irritation as more pests bite at the animal’s skin. This generational life cycle will continue until the problem is fully addressed.

Symptoms of a Flea Allergy in Cats

The most common symptom of a flea allergy in cats is severe itching. This itching, known as pruritis, this side effect can occur with even as few as one or two flea bites. These symptoms may even persist after a treatment has been applied.

The itching most commonly appears to affect the front of the cat’s body and around the head, however, the lesions brought on by bites can occur all over the cat’s body. The fleas may not be visible to the human eye, and may not appear with the aid of a flea comb because cats are such thorough groomers, but if the scratching persists, it may still point to a flea allergy.

The symptoms of a flea allergy may be more severe during warm and humid weather, and in similar climates, but even in northern, colder climates and in the colder months, fleas can still continue to populate on your cat due if the animal is spending time in a heated home.

This means that flea allergies can be a chronic, year-round issue that may take a long time to resolve. The animals will scratch, lick, chew, and bite at his skin excessively and cause red, oozing hot spots to appear where they have focused their attention. Cats may even remove large clumps of hair to get at their lesions and find some temporary relief. If their infestation is allowed to grow, they may have tiny flea bite lesions all over their body, particularly on their neck and rear.

Even if the tell-tale signs of a flea infestation is removed due to your cat’s excessive grooming, there are still other pointers you can look for. These symptoms include:

  • Constant scratching and grooming, sometimes overly-intense
  • Chewing and biting at the tail, hind end, and legs
  • Open, oozing sores on the cat’s skin (hot spots)
  • Skin damage due to excessive scratching and itching
  • Bald spots and hair loss
  • Skin inflammation
  • Scabs and crusts
  • Darkening or thickening of the affected skin
  • The unpleasant odor that emerges as a result of a secondary infection
  • Visual identification of fleas
  • Blackish debris at the base of the hair (flea excrement)

If you are able to comb through your cat’s fur and find traces of flea excrement it means that things have developed to an intense infestation. This is a tell-tale sign of a bad situation because of how religious cats generally are about grooming themselves. If excrement is visible, it points to a real problem that you need to address immediately.

How is a Flea Allergy in Cats Diagnosed?

The easiest way to diagnose a flea allergy in your cat is to run a flea comb through his fur. If you’ve noticed your cat scratching at himself more often than usual, it may point to a flea allergy. Combing through his fur may reveal fleas, and if so, you can likely deduce that they are the cause and treat accordingly.

However, sometimes cats have groomed away the majority of the issue and you won’t find any fleas when you comb through their fur. This doesn’t necessarily mean that a flea allergy is not the cause, despite the fact that many allergens and other substances can cause similar symptoms.

If this is the case, you will need to have your veterinarian conduct allergy testing to determine what it is in your cat’s environment that is causing the reaction, or perhaps even something like a feline food allergy. Your vet will test your cat’s sensitivity to flea saliva as well as to other allergens.

You may even move forward and treat your cat for fleas even if no fleas are found during your physical examination. If the symptoms improve, you’ll know it was indeed a flea allergy that was causing the reaction. But if not, you will need to keep searching to find the cause.

You will move step by step through different tests for various allergens as well as review your cat’s history of behavior and symptoms to try and pinpoint the cause. Your veterinarian will prescribe a treatment plan for the suspected issue, and may also prescribe treatments for any secondary issues that have resulted from your cat scratching at his bites.

Treating Flea Allergies in Cats

Flea allergies are generally treated in two phases. First, you need to control the flea problem and get rid of the fleas on your cat’s body. Second, you may need to treat any infections that have come as a result of the incessant scratching due to the allergy.

These treatments will often include topical remedies, antibiotics, steroids, and other medications to help control the itch and eradicate the flea problem.

Truly, the only effective treatment is to get rid of the fleas from the cat and his environment. Treating the itching will provide some temporary relief (which your cat will appreciate), but the symptoms will return if the flea problem is not properly addressed. This flea treatment will target adult fleas as well as eggs and larvae which live in the cat’s environment and will mature into adult fleas.

Treatment will typically involve using a flea shampoo to kill the pests lingering on the cat’s body, as well as other topical treatments to help with hot spots that have developed as a result of the allergy. Steroids may also be prescribed for more severe conditions to help with the itching as well.

If an infestation has been established anywhere in the cat’s environment, the fleas will be difficult to remove, but there are pesticides available to help clear out your cat’s living spaces. This includes problem areas both inside and outside of the home. Your house, your yard, and all other pets must also be treated with flea-control products to completely get rid of the problem.

Professionals recommend that you clean any of your furniture, carpeting, pet bedding, or other items that may be hosting the fleas. Although this may be impossible especially if your cat roams outside, try to limit your cat’s exposure to any other animals in the wild that may be infested with fleas.

While there are numerous options on the market for providing temporary relief, completely eradicating the flea problem may prove to be a difficult endeavor. Treatments should be applied repeatedly to your cat and the cat’s environment until you are confident the problem is taken care of completely. Moving forward, stay consistent with your monthly flea treatment, as your cat will always suffer from this allergy. Continued treatment will help to ensure that symptoms do not return.

Managing Your Cat’s Flea Allergy

Continued treatment is the key to managing your cat’s flea allergy. It only takes one or two bites for your cat to display allergy symptoms, so it is best to be consistent with treatment using flea control products. You should bathe your cat with flea shampoo frequently and use spot treatments as needed.       

Since fleas don’t actually live on your cat, don’t forget to treat the areas of your home and yard where they may be lurking. Monthly treatments during flea season can help to keep a flea-free environment around your house or backyard. Even if you can’t see them, they are likely still around.

Being aggressive and staying ahead of a potential flea problem is often your best course of action.

You should also make sure you vacuum your home regularly including furniture, chairs, blankets, and any other spots your cat likes to cuddle up and take a nap. When you do vacuum, make sure to throw out the bag or dump the vacuum in a trash bag and seal it before throwing it away so any captured fleas do not escape and re-enter your home.


Anytime your cat appears to be having any kind of allergic reaction you should immediately consult your veterinarian. While they are generally non-harmful to your cat beyond being a nuisance, allergies can lead to other health conditions such as bacterial and fungal infections.

Whenever your cat has a bad reaction or a treatment doesn’t work, seek your veterinarian for other options. Be consistent with your treatments and you and your cat can resume life flea-free.



“Flea Control and Flea Bite Allergies in Cats.” PetMD, Accessed 5 Dec 2018.

“How to Help Pets with Flea Allergy Dermatitis.” CANIDAE®, Accessed 5 Dec 2018.

“Flea Allergy Dermatitis in Cats and Dogs.” Vetstreet, Accessed 5 Dec 2018.

“Flea Allergy Dermatitis in Cats.” Pet Health Network,

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