Summary

• Urticaria is a skin condition characterised by erythematous, blanching, oedematous, non-painful, pruritic lesions that typically resolve within 24 hours and leave no residual markings.
• Angio-oedema is swelling involving the deeper layers of the sub-dermis and occurs in association with urticaria in about 40% of cases. It can also occur in the absence of urticaria.
• Acute urticaria lasts less than 6 weeks and is typically due to a hypersensitivity reaction to a specific trigger and is generally self-limiting. Chronic urticaria is characterised by daily or near-daily episodes of hives occurring for 6 weeks or more and has a complex aetiology.
• Diagnosis of acute and chronic urticaria is based on history and physical examination; diagnosis of chronic urticaria usually involves additional laboratory testing.
• Referral to a specialist may be appropriate, especially in cases of chronic urticaria.
• Antihistamines are the mainstay of therapy for both acute and chronic urticaria. Immunomodulator drugs are indicated for selected patients with chronic urticaria.
• Angio-oedema involving the face or neck can compromise the airway and requires prompt treatment with adrenaline (epinephrine).