Hives are a reaction of the skin caused by the release of histamine that occurs in response to irritation. They appear as raised, puffy bumps of varying shape and size that are itch intensely. Hives can look reddish on light-colored skin but may be harder to see on darker skin.

Hives can occur alone, in response to an allergen, or triggered by:

  • Colds
  • Infection
  • Insect stings or bites
  • Medications
  • Changes in body temperature
  • Sweating
  • Exercise

Most episodes of hives are transient, but some people experience chronic hives with episodes that may occur daily for several months or years. 

Source: American Academy of Family Physicians. (2017, June 1). Hives. American Family Physician. Retrieved February 6, 2022, from