Tiny purple or red spots or bruises (petechiae) after a bite or sting

Petechiae (say "pet-TEA-key-eye") are tiny, flat red or purple spots in the skin or lining of the mouth caused by abnormal bleeding in small blood vessels that have broken close to the skin or the surface of a mucous membrane. Petechiae appear rapidly over hours.

• Petechiae spots are from pinpoint- to pinhead-sized. They are different from tiny, flat red spots or birthmarks (hemangiomas) that are present all the time.
• They may spread over a large area of the body.
• They do not itch like many rashes.
• They do not turn white (blanch) when you press on them.

Petechiae that develop quickly over a short period of time (a few hours) may mean the person has a serious infection or lack of blood platelets (part of the body's defense against bleeding) that requires immediate medical treatment.

Many people have tiny, flat red spots (hemangiomas) that are present all the time. If they have been present for a while, these spots are not a concern.

If new red or purple spots develop rapidly over hours, this may indicate a serious condition (such as the blood not clotting normally) requiring immediate medical treatment.

In rare cases, the bite of a brown recluse spider can cause this type of reaction.