Urticaria

Hives: Erythema /  flare  /  raised wheal with central pallor (if classic)
  • KEY:  both transient and migratory.  Appear, disappear, & pop up somewhere else.
  • VERY itchy
  • Can Dx by such a history alone
Bug Bites mimic hives, but remain permanently until resolution
  • Hives vanish & migrate
Causes
  • Infections (viral & bacterial), esp. in children.
  • Medications, esp. antibiotics & NSAIDs
  • Shellfish
  • Nuts
  • In children: also milk, eggs, soy, wheat, tomatoes, strawberries
  • Narcotics, esp. codeine (no hives; since not an IgE-mediated allergy)
  • Certain parasites in returning travelers (only if there’s eosinophilia on CBC)
  • Latex if excessive (e.g. gloves all day)
  • Physical Urticarias, due to pressure, cold, heat, exercise, or sunlight

An association is convincing if the reaction occurred within 2 hours of food ingestion.

  • Suspect a recent medication no matter when in the course it happened.
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