(HealthDay News) - Hives are red, raised patches of skin that are usually very itchy. Hives themselves often are not serious, but they may indicate a more serious condition.

The U.S. National Library of Medicine lists these common triggers for hives:

  • Some medications.
  • Foods that many people are allergic to, including shellfish, nuts, eggs and milk.
  • Pollen.
  • Dander from animals, notably cats.
  • Bites from insects.
  • Infections and some illnesses, including lupus and leukemia.
  • Stress or anxiety.
  • Prolonged exposure to the sun or the cold.
  • Excessive sweating.