We all get stung or bitten by insects every now and then – and most people end up with a small, red, itchy bump as a result. But those who are allergic to insect stings or bites may react to them strongly, and the reaction might even be life-threatening in rare cases.
In insect venom allergies, the body’s immune system attacks certain parts of proteins that enter the body when the insect bites or stings. It's not known why that happens. But this allergy doesn’t develop after the first sting or bite: Sometimes people get stung or bitten over many years without having an unusual reaction. Over time, though, their bodies become more sensitive to the venom in the sting or bite (sensitization) and they then suddenly have an allergic reaction to it.