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Diseases & Conditions

Frequently Asked Questions

Q: What causes hives and angioedema?

A. Hives and angioedema form when blood plasma leaks out of small blood vessels in the skin because a chemical called histamine is released. Histamine is released from mast cells along the blood vessels in the skin. Allergic reactions, chemicals in foods, insect stings, sunlight exposure or medications can cause histamine release. Sometimes it's impossible to find out why hives have formed.

Q: How can hives be managed?

A. While you’re waiting for the hives and swelling to disappear, here are some tips:

  • Avoid hot water; use lukewarm water instead
  • Use gentle, mild soap
  • Apply cool compresses or wet cloths to the affected areas
  • Try to work and sleep in a cool room
  • Wear loose-fitting lightweight clothes

Q: When should I call the doctor?

A. If hives or angioedema occur with any of the following symptoms, please contact your doctor right away:

  • Dizziness
  • Wheezing
  • Difficulty breathing
  • Tightness in the chest
  • Swelling of the tongue, lips or face

Also contact your doctor if your hives have lasted longer than a few days, if they continue to recur over a month or longer, or if you have symptoms of angioedema or anaphylaxis.