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What is Flea Bite Allergy?

It is quite common for cats to be allergic or hypersensitive to flea bites. Recent studies have determined that 15 different antigens in the saliva of the flea exist, and each one is capable of causing an allergic reaction from your cat. Despite advances in control methods for fleas, they remain a common problem for cat owners. When eliminating a flea problem, you need to not only treat your cat, but treat the environment as well (your house and your cat’s bedding).

A cat with an allergy to flea bites is a common finding, with the flea saliva believed to be the cause, and development at an early age.

Symptoms of Flea Bite Allergy in Cats

  • Severe itching which is a condition medically referred to as pruritus
  • Scratching which causes injury or broken skin
  • Secondary infection 
  • Depression
  • Irritability
  • Fur loss
  • Bald areas 
  • Lesions


  • Flea allergy dermatitis (FAD) is a form of allergy or hypersensitivity in cats 
  • When the flea bites they inject saliva into your cat’s skin 
  • It is the saliva that causes an allergic reaction 
  • Some cats are more prone to these allergies 
  • Only eradication of the flea brings relief 
  • Constant regular treatment is needed

Causes of Flea Bite Allergy in Cats

  • The culprit for this allergic condition is the common brown wingless cat flea who takes up residence in your cat’s coat
  • To them, your cat is the ideal environment to live and provides all the essentials it needs 
  • Your cat provides warmth, moisture and food in one convenient location 
  • It is the flea saliva that causes the allergic response in your cat
  • Flea allergy dermatitis (FAD) is a form of allergy or hypersensitivity in cats
  • When the flea bites they inject saliva into your cat’s skin 
  • Some cats are more prone to these allergies 
  • Only eradication of the flea brings relief 
  • Constant regular treatment is needed 
  • Allergies are an exaggerated response to a stimulus (the saliva) 
  • Histamine is released in response to the stimulus 
  • Once your cat is allergic, they remain so
  • A related condition called neurodermatoses can occur from anxiety caused from the hypersensitivity 
  • Hind end is usually the area affected most

Diagnosis of Flea Bite Allergy in Cats

Your cat’s behavior will alert you to the presence of fleas. The constant itching and scratching or your cat biting at the base of his tail, the thinning fur and red inflamed skin will all point to the flea infestation. A quick trip to the veterinary clinic can help with diagnosis and ensure that you are treating the right complaint. Your specialist will examine your cat and may do intradermal skin testing to determine the cause although the test is not failproof. If your cat is allergic to flea bites, it only needs one or two fleas to produce a reaction. From a kitten into adulthood, flea control should become part of your regular pet care maintenance program.

A kitten who is introduced to a flea collar will adjust quicker than your adult cat who would be perhaps better off with an oral or topical product. Applying the topical product high on the back of the neck of your cat will ensure your kitty will not be able to lick it off. Your veterinarian will advise you on treatment for infected skin caused by your cat scratching to relieve the itch. This secondary bacterial infection can become an additional problem if not treated. The use of a flea comb is a good way to determine if you cat has any fleas or flea eggs on them allowing you to monitor the flea situation.

Treatment of Flea Bite Allergy in Cats

The prevention and control of the fleas are essential for your cat’s well being. The marketplace is saturated with products all capable of killing the adult flea for a period of time but it is vital to continue using the treatment to stay on top of the situation. Products vary from topical spot applications to oral products. Flea shampoos are available for the obliging cat. But the emphasis is on constant management of a long-term product. Controlling the flea situation for your outdoor cat is virtually impossible – short term products may provide a solution but be aware that your cat may bring fleas in on him to infect your house. This creates another problem that needs to be addressed to overcome the flea problem. 

If fleas get into your house they may actually end up biting you after they have been evicted from their host animal (your cat) through product treatments. If this is the case, then the whole house will need to be treated for everyone’s sake. If your cat is allergic to flea bites then they may need steroids or antihistamines to combat their condition. The other thing to consider is the injury that your cat can inflict upon itself when scratching. These injuries can become infected by bacteria as a result of the open lesions, so your veterinarian may prescribe antibiotics. Follow up trips to your veterinarian are often required to check your cat’s progress.

Recovery of Flea Bite Allergy in Cats

Your cat will recover quickly once treatment begins and will remain healthy as long as fleas are kept at bay. Management is essential to ensure flea control is maintained. Getting into a habit of applying treatments or replacing flea collars will pay off with a very happy cat and will put your mind at rest that your home is not being infested as well. The choice of products is extensive but don’t think because the recommended dose is good that a double dose would be better.

Remember that these products are chemicals and too much can affect the health of your cat. Stick to the recommended amount and always seek advice from a qualified veterinarian. Because your cat is a very fastidious creature and grooms itself regularly, you can’t rely on just visual observation. Vigilance and observation combined with regular treatments are key to overcoming this issue.

Flea Bite Allergy Questions and Advice from Veterinary Professionals

Russian Blue maine coon
8 Months
Mild condition
0 found helpful
Mild condition

Has Symptoms


I'm worried about my kitty his fur is oily like he's not grooming and his gums are very pale, he has no energy and isn't playful he sounds sad or in pain when he meows and like he feels kinda boney but his belly is fat, he just doesn't look happy

Dr. Callum Turner, DVM
1675 Recommendations
If Darcy is showing this level of symptoms you should visit your Veterinarian as pale gums and lethargy may be indicative of anaemia or other condition. Various conditions like infections, parasites, hormonal conditions among other causes may be attributable to these symptoms. Regards Dr Callum Turner DVM

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