What is Urticaria?

Urticaria, or hives, is a condition in which red, itchy, and swollen areas appear on the skin – usually as an allergic reaction from eating certain foods or taking certain medicines.

Foods commonly cause hives:

  • nuts
  • tomatoes
  • shellfish
  • berries

Medicines commonly cause hives:

  • penicillin
  • sulfa
  • anticonvulsant drugs
  • phenobarbital
  • aspirin


  • dermatographism – hives caused by scratching the skin, continual stroking of the skin, or wearing tight-fitting clothes that rub the skin.
  • cold-induced – hives caused by exposure to cold air or water.
  • solar hives – hives caused by exposure to sunlight or light-bulb light.
  • exercise
  • chronic urticaria – recurrent hives with no known cause
  • Emotional stress
  • Excessive perspiration
  • Illness (including lupus, other autoimmune diseases, and leukemia
  • Infections such as mononucleosis


  • Itching
  • Swelling of the surface of the skin into red- or skin-colored welts (called wheals) with clearly defined edges

The hives may get bigger, spread, and join together to form larger areas of flat, raised skin.

They can also change shape, disappear, and reappear within minutes or hours. A true hive comes and goes. When you press the center of one, it turns white. This is called blanching.