Fleas that live on humans (Pulex irritans) are relatively uncommon. The species that humans are most likely to encounter is the cat flea (Ctenocephalides felis), which also infests dogs. Humans may also encounter the dog flea (Ctenocephalides canis) or the rat flea (Xenopsylla cheopis). Cat, dog, and rat fleas do not live on people, but they will bite a human if they encounter one and are looking for a blood meal.
Fleas most often bite people around the legs and the ankles. The resulting red bump is an allergic reaction to flea saliva. The bites, which are usually but not always felt immediately, become increasingly irritated and may remain sore and/or itchy for as long as a week. Itching may be just at the site of the bites or more generalized in nature.
Some people are more sensitive to flea bites than others, and it can sometimes appear that the fleas are "picking on" one individual in a household but not others. Children aged younger than 10 are generally more sensitive than older people, as people tend to become desensitized by repeated exposure over time. Flea bites in children produce an allergic reaction in which recurrent or chronic small red bumps occur on the exposed skin areas. Individuals who are hypersensitive to fleas may also develop blister reactions.
Flea bites produce a variety of effects, ranging from a small, temporary red bump to long-term symptoms that may last for years depending on the sensitivity of the person bitten. The area of skin affected may increase over time, or the rash may spread to a different area. Flea bites can take a very long time to heal up and can sometimes evolve into "persistent bite reactions." Itching and swelling may occur at the sites of older bites when the person is bitten again.
- Burrow's solution compresses applied to the bites
- Calamine lotion to which 0.25% menthol may be added by the pharmacist
- 1% hydrocortisone cream may take the edge off the itch
Flea control at home may be regulated by the following measures:
- Bedding should be clean and laundered regularly.
- Bedrooms should be vacuumed regularly, especially in the corners underneath the beds.
- The indoor environment can be sprayed with methoprene, a new chemical used for flea infestation.
- A professional exterminator may be needed.
- Pets should be kept clean and regularly checked by a veterinarian.
- Flea shampoos mechanically remove fleas but need to be followed by a flea control rinse that contains insecticide.
- Flea dust powders
- Flea collars
- Oral flea medication (available from the vet)
- Itch is not alleviated using over-the-counter products
- The bites become infected due to scratching
- Blisters form in reaction to flea bites
- Bites do not resolve in a few weeks
Antihistamines may be prescribed for the relief of the itching. Be aware that some antihistamines cause drowsiness.
- Diphenhydramine hydrochloride (Benadryl®) – 25, 50 mg tablets or capsules, 25–50 mg nightly or every 6 hours as needed
- Cetirizine hydrochloride (Zyrtec®) – 10 mg tablets, 10 mg per day
Centers for Disease Control and Prevention. Questions and Answers About Plague. http://www.cdc.gov/ncidod/dvbid/plague/qa.htm. Reviewed August 6, 2009. Accessed September 30, 2010.
Bolognia, Jean L., ed. Dermatology, 2nd ed. pp.1305-1306. New York: Mosby, 2008.
Wolff, Klaus, ed. Fitzpatrick's Dermatology in General Medicine. 7th ed. pp.1758-1759, 2061-2062. New York: McGraw-Hill, 2008.