The welts that come with hives arise when certain cells release histamine and other chemicals into your bloodstream.

Doctors often can't identify the reason for this skin reaction, or why it sometimes turns into a long-term problem (chronic hives). But the skin reaction may be triggered by:

  • Pain medications
  • Insects or parasites
  • Infection
  • Scratching
  • Heat or cold
  • Stress
  • Sunlight
  • Exercise
  • Alcohol, food or food additives
  • Pressure on the skin, as from a tight waistband
Jun. 13, 2014

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