Hornets and yellow jackets are types of wasps, which are in the same family of insects (Hymenoptera) as bees and fire ants. Wasps can sting a person repeatedly without losing their stingers, and reactions can vary from minor to severe.

Wasp stings cause different reactions in people:

• Most people have a minor reaction, with a bump or wheal at the site of the sting. Intense immediate pain and itching may be present and may last from a few hours to a few days.
• A toxic reaction can occur when a person has been stung 10 or more times.
• A severe, life-threatening allergic reaction can occur (anaphylaxis).
• A large skin reaction can occur, causing redness and swelling to extend beyond the sting site. This reaction lasts about 3 to 4 days.
• Serum sickness is a rare reaction to stings in which flu-like symptoms and hives develop 7 to 14 days after an insect sting.

Wasps are usually more aggressive than bees. Yellow jackets cause the most allergic reactions.

Home treatment is usually all that is needed to relieve pain and itching from minor reactions. Severe reactions require emergency medical treatment.