Flea Allergy Dermatitis

Flea allergy dermatitis is a common allergy in pets. It is a reaction to flea saliva when fleas bite the pet. It causes the pet to be extremely itchy and they can develop secondary skin infections as a result.

Pets do not have to have a LOT of fleas to have a reaction. A few bites can cause an intense response!

Fleas are bloodsucking insects with a life span of 6 to 12 months. This life span is influenced by environmental conditions and can vary from two to three weeks up to a year. The adult flea spends most of its life on the host, while the immature stages (eggs, pupae, larva) are found in the environment.

Signs of Flea Allergy

  • Severe itching, especially at the tail, back, and legs
  • Oozing lesions (lick granuloma) from chewing
  • Hot spots from severe scratching


Flea allergy dermatitis is a common cause of itchiness and scratching in dogs, but other medical problems such as allergies and mange can lead to similar symptoms and should be evaluated by your veterinarian.

Diagnosis of flea allergy is made based on history, clinical signs and a positive response to flea control.


Treatment of flea allergy dermatitis involves three phases:

  • Prevention of flea bites. The most important part of treatment is preventing flea bites with aggressive flea control on your pet and in the environment.
  • Use an effective, quick, long-lasting, and safe flea control product on your pet all year round. We recommend Nexgard and Bravecto for dogs and Revolution Plus for cats because of their quick flea kill.
  • Treat the environment by vacuuming and disposing of vacuum bags, using flea bombs in the house, and pest control treatment for yards.
  • Treatment of secondary skin infections. Antibiotics and antifungal drugs may be necessary to treat secondary skin infections triggered by the flea allergy.
  • Breaking the itch cycle. If your pet is intensely itchy, a short course of medications may be necessary to break the itch cycle and make your pet more comfortable.