What happens if I scratch flea bites?

Summary

Scratching flea bites can inflame the bite area and delay healing. If the skin is broken, secondary infections can develop. Infected bites take much longer to heal and may cause scarring.

Details

Superficial Scratching

Flea bites can be extremely itchy, and often provoke scratching. Unfortunately, scratching or rubbing a flea bite can inflame the skin, increasing the sensitivity of nerves in the area. This can re-trigger the whealing lesion, and cause the bite to take longer to heal.

Scratch-Itch Cycle

Scratching a flea bite will briefly relieve itching by overstimulating the sensory circuits. However, nerves in the area then become more responsive and sensitive, which causes further irritation and inflammation, which in turn induces more scratching. This is called the scratch-itch cycle.

Secondary Infections

Excoriation (scratching, picking, squeezing, etc) of flea bites can break open skin, release fluid, and cause crusting. Broken skin commonly results in secondary infections, either bacterial or fungal. Infected lesions can ooze, crust, and scab. Infected bites may fill with pus and resemble pimples (pustules and boils).

Secondary infections remain mildly to moderately itchy. They heal over 4 to 6 weeks, which is significantly longer than typical flea bites. Discolored skin (hyperpigmentation) remains longer. Scarring can also occur from infected bites.

Secondary infections can be prevented by avoiding scratching, keeping hands nails clean, and using moisturizer on the bite area so skin doesn’t dry and crack open.

Flea Allergy Dermatitis

Some dogs and cats are severely allergic to flea bites. This is called flea allergy dermatitis (FAD). Afflicted animals may scratch, bite, lick, and chew excessively at itchy and inflamed areas. This can result in further inflammation, redness, greasy seborrheic crusting, scabs, and discolored, thickened (lichenified) skin. Tufts of hair can get removed during grooming, causing alopecia. Red, oozing lesions called hot spots may develop in areas where the scratching is most intense. When the skin is broken, secondary skin infections are common along with an accompanying foul odor.

References