Flea bites don’t hurt. Most people aren’t aware of being bitten until an itchy skin reaction develops. A wheal appears soon after the bite that isn’t too irritating and fades quickly. However, 24 hours after the bite, a hard bump called a papule forms. The papules cause considerable itching.
Flea Bites aren’t Felt Initially
Flea bites aren’t painful. In fact, people are often unaware of being bitten unless they see the flea. Most bites are noticed once a skin reaction develops, which may not occur until a day later.
When fleas bite, they introduce saliva into the surrounding skin. The saliva prevents blood coagulation, and spreads and softens dermal tissue. This allows their needle-like mouths to easily penetrate the skin. Only one stylet pierces into the blood vessel. Once the meal is over, the stylet is rapidly withdrawn and there’s remarkably little damage done to the host.
Immune Response & Itching
Flea bites vary in severity, depending on the host’s individual response and sensitivity due to previous exposure. Most people experience both an immediate and delayed reaction.
After a flea bites, the affected skin rises in 5-30 minutes. This is called whealing, and it’s similar to what happens with mosquito bites. Wheals cause mild itching, but they usually don’t bother people much. The effects aren’t too irritating and they’re short-lived.
The wheal fades in 12-24 hours and is replaced by a papule. A papule is a solid bump, like a welt. The papules are extremely itchy and bothersome. The severity of the irritation peaks in 12-24 hours. The itchy lesions may induce scratching and rubbing, which can lead to secondary bacterial infections.