• In urticaria (hives), both wheals and angioedema are present. Wheals result from localized edema of upper dermis, while angioedema results from edema of lower dermal and subcutaneous tissues[1]
  • Mast cell and basophil activation involving the release of vasoactive substances
  • Broad differential diagnosis of etiologies
    • Sometimes iatrogenic; for example, skin wheals from intradermal lidocaine infiltration, allergy skin prick test, tuberculin skin test

Clinical Features

  • Papules that are well-circumscribed but irregular, pruritic, and often with a pale center and red flare on the borders
  • Transient duration, usually hours, with spontaneous self-resolution
  • If related to anaphylaxis or allergy, may also involve other systems such as respiratory, circulatory, GI
Urticarial wheal

Differential Diagnosis


  • Clinical diagnosis
    • Take a thorough history to assess for precipitating factors, including recent foods, travel, medications/treatments, insect bites/stings, autoimmune disease, viral infections, anaphylaxis history, etc
    • Check for association with overlying objects such as watches, jewelry clothing, bands, etc


  • If any suspicion of anaphylaxis, treat with IM epinephrine
  • 2nd gen H1 antihistamines are effective; if ineffective, consider corticosteroids and H2 antihistamines[2]
  • Avoid any causative agent or medications if identified, and treat the underlying illness


  • Observe in ED for 4-6 hours until symptoms improve; utilize clinical gestalt
  • If anaphylactic picture, after observation discharge with anaphylaxis emergency plan and epipen

See Also


  1. Bernstein JA, Moellman J. Emerging concepts in the diagnosis and treatment of patients with undifferentiated angioedema. Int J Emerg Med. 2012 Nov 6;5(1):39. doi: 10.1186/1865-1380-5-39. PMID: 23131076; PMCID: PMC3518251.
  2. Schaefer P. Acute and Chronic Urticaria: Evaluation and Treatment. Am Fam Physician. 2017 Jun 1;95(11):717-724. PMID: 28671445.