Insect bites and stings can cause an immediate skin reaction. The bite from fire ants and the sting from bees, wasps, and hornets are usually painful. Bites caused by mosquitoes, fleas, and mites are more likely to cause itching than pain.

In most cases, bites and stings can be easily treated at home. However, some people have a severe allergic reaction to insect bites and stings. This is a life-threatening allergic reaction known as anaphylaxis, and it requires urgent emergency care. Severe reactions can affect the whole body and may occur very quickly, often within minutes. These severe reactions can be rapidly fatal if untreated. Call 911 if you are with someone who has trouble breathing or goes into shock.

Some spider bites, like those of the black widow or brown recluse, are also serious and can be life-threatening. Most spider bites, however, are harmless. If bitten by an insect or spider, bring it for identification if this can be done quickly and safely.

The non-emergency symptoms vary according to the type of insect and the individual. Most people have localized pain, redness, swelling, or itching. You may also feel burning, numbness, or tingling.