FFinalistSouthampton · 2027
Dermatology
AKT · Dermatology/Inflammatory & papulosquamous

Urticaria

Mast-cell histamine release → transient dermal weals ± angioedema

Overview

Superficial dermal swelling (weals/hives) from mast-cell histamine release, sometimes with deeper angioedema. Acute (=6 weeks; spontaneous or inducible). The hallmark is that each individual weal is fleeting and leaves no mark.

Recognise

  • Transient, intensely itchy pink/white weals — each LESION lasts <24 hours and resolves with no bruising or scarring
  • Angioedema (deeper swelling of lips, eyes, tongue) in some; dermographism
  • Triggers: viral infection, foods, drugs (NSAIDs and opioids as direct mast-cell degranulators; ACE inhibitors for angioedema), and physical stimuli (cold, pressure, cholinergic)

Red flags

  • Angioedema with airway or breathing compromise / anaphylaxis → IM adrenaline
  • An individual weal lasting >24 hours, painful, or leaving bruising/staining → urticarial vasculitis (biopsy)

Differentials & how to tell them apart

Urticarial vasculitisweals last >24 hours, are painful and bruise/stain; systemic features — biopsy
Erythema multiformefixed target lesions that persist over days, not fleeting weals
Anaphylaxissystemic — hypotension, wheeze, airway involvement
Bullous pemphigoid (urticarial phase)urticarial prodrome in an older patient, then tense blisters

Clinical image

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Urticaria — clinical imagesDermNet

Investigations

Acute spontaneous urticaria needs no investigation. Chronic → FBC, CRP/ESR, consider thyroid autoantibodies; skin biopsy if urticarial vasculitis is suspected; allergy testing only with a clear trigger.

Management

Regular non-sedating H1-antihistamine + avoidance of identified triggers

  1. 1Standard-dose non-sedating H1-antihistamine + avoid triggers; a short course of oral prednisolone for a severe acute flare.Gate: A weal lasting >24 hours, painful, or leaving bruising/staining is NOT ordinary urticaria → suspect urticarial vasculitis and biopsy; and angioedema compromising the airway is treated as anaphylaxis (IM adrenaline)
  2. 2Chronic urticaria with inadequate response → up-titrate the non-sedating antihistamine up to 4x the licensed dose.
  3. 3Chronic refractory disease → refer; omalizumab; ciclosporin.
Non-sedating H1-antihistamine (cetirizine, loratadine, fexofenadine) — first-line; can be up-titrated to 4x the licensed dose in chronic urticaria
Short oral corticosteroid course — for a severe acute flare
Omalizumab (anti-IgE) — chronic spontaneous urticaria refractory to antihistamines (specialist)
IM adrenaline — angioedema with airway compromise / anaphylaxis

Key points

ACE inhibitors cause angioedema WITHOUT weals (bradykinin-mediated) — it does not respond to antihistamines, so stop the drug. NSAIDs and opioids are common non-allergic triggers.

Monitor & prognosis

Symptom control (chronic: UAS7); response to omalizumab.

Acute urticaria is self-limiting; chronic spontaneous urticaria often remits over 1–5 years.

Source: NICE CKS Urticaria; BSACI guideline