Clinical features

• the rapid appearance of erythematous, often itchy, swellings are characteristic
• urticaria can be localised or generalised (1)
  • may take the form of blotches, blisters, or wheals varying in size and shape
  • are transient and usually disappear within a few hours.
  • sites of constriction by clothing are common sites
    
    
• systemic reactions cannot be seen in most of the patients but on rare occasions allergic and some physical urticarias may develop into anaphylaxis. Note though that urticaria is a frequent finding in anaphylactic and anaphylactoid reactions (2)
  
  
• an acute urticaria rash may cover most of the skin surface
• in chronic urticaria, only a few wheals appear each day
  
  
• angioedema presents in the lips, genitalia and hands; it is life-threatening if the tongue and larynx are affected

Click here for images of urticaria

Reference:

1. Zuberbier T, Abdul Latiff AH, Abuzakouk M, et al. The international EAACI/GA²LEN/EuroGuiDerm/APAAACI guideline for the definition, classification, diagnosis, and management of urticaria. Allergy. 2022 Mar;77(3):734-66.

2. Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis - a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020 Apr;145(4):1082-123