With most insect or tick bites, you get a pink, itchy bump that swells slightly, then fades in about a week. But some people react worse to stings or bites. And if you have an allergy, reactions can be life threatening. Bites by certain spiders can also have severe consequences, including death. Sometimes bites can cause infectious diseases, such as Lyme disease transmitted by a tick bite.

In other cases, the bite may be an annoyance only, clearing up in a few days. But sometimes a reaction to an insect or tick bite may last for weeks, months, or years. For example, if a tick part remains in the skin after a bite, your immune cells may react to this “foreign body” by surrounding it and “walling it off” from the rest of the skin. The swelling goes away, but a pink bump called a “tick bite granuloma” may persist.

You can apply cortisone to early bites to help with itching and to decrease the skin reaction. But creams or lotions probably won’t get rid of a granuloma. These persistent bumps can be surgically removed if they bother you.

But bumps on the skin are not always caused by insect or tick bites — and may be other growths. See your doctor if a bump persists or changes. He or she can biopsy these suspicious growths to confirm what they are.