► Health TopicsSkin and RashesFleas



Fleas are small insects that feed on the blood of humans, dogs, cats, and other warm-blooded animals.

Alternative Names

Dog fleas; Siphonaptera


Fleas prefer to live on dogs and cats. They may also be found on humans and other warm-blooded animals.

Pet owners may not be bothered by fleas until their pet has been gone for a long period of time. Fleas look for other sources of food and begin to bite humans. Bites often occur around the waist, ankles, armpits, and in the bend of the elbows and knees.


Symptoms of flea bites include hives, itching, and rash.

The rash:

  • Has small bumps, often three bumps together, that may itch and bleed
  • May be located on the armpit or fold of a joint (at the elbow, knee, or ankle)
  • Turns white when pressed
  • May develop in skin folds, such as under breasts or in the groin

Flea bites can also cause swelling around a sore or injury.

Exams and Tests

A skin biopsy is sometimes done.


The goal of treatment is to get rid of the fleas. This can be done by treating your home, pets, and outside areas with chemicals (pesticides). Small children should not be in the home when pesticides are being used. Birds and fish must be protected when chemicals are sprayed. Home foggers and flea collars do not always work to get rid of fleas. If home treatments do not work, you may need to get professional pest control help.

You can use an over-the-counter 1% hydrocortisone cream to relieve itching. Antihistamines you take by mouth may also help with itching.

Outlook (Prognosis)

Getting rid of fleas can be hard and may take many tries.

Possible Complications

Scratching can lead to a skin infection.


Prevention may not always be possible. Use of chemical sprays may be helpful if fleas are common in your area. Professional pest control may be needed in some cases.



Elston DM. Bites and stings. In: Bolognia JL, Jorizzo JL, Schaffer JV, et al, eds. Dermatology. 3rd ed. Philadelphia, PA: Elsevier Mosby; 2012:chap 5.

Habif TM. Infestations and bites. In: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, PA: Elsevier Mosby; 2009:chap 15.

James WD, Berger TG, Elston DM. Parasitic infestations, stings, and bites. In: James WD, Berger TG, Elston DM, eds. Andrews' Diseases of the Skin: Clinical Dermatology. 11th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 20.

Nicklaus Children's Hospital

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