Synopsis
Recognise reproducible physical urticaria phenotypes, use controlled provocation safely, reduce trigger risk without disabling avoidance, and treat symptoms with non-sedating antihistamines.
- A consistent stimulus-to-wheal relationship distinguishes inducible urticaria; document delay, threshold, duration and whether symptoms extend beyond exposed skin.
- Symptomatic dermographism causes itchy linear wheals after stroking, whereas simple dermographism without symptoms does not require treatment.
- Cholinergic urticaria produces small itchy wheals with heat, emotion or exercise; systemic exertional symptoms require evaluation for exercise-induced anaphylaxis.
Key red flags
Syncope in water, throat symptoms after cold food, exertional collapse, systemic symptoms with heat, or swelling beyond the provoked site requires urgent allergy assessment and an emergency plan.
Generalised wheals, dizziness, breathing difficulty or collapse with swimming indicates anaphylaxis risk and requires strict safety planning.
Investigation priorities
Establish reproducibility, latency, threshold and cofactors before challenge.
Management branches
Wheals remain local, physiology is normal and a consistent physical trigger is identifiable.
- Document the stimulus, latency and threshold, then perform a low-risk standardised provocation when confirmation will change behaviour or treatment.
- Modify exposure proportionately using protective layers, load breaks, temperature planning or contact substitution instead of prohibiting all activity.
Key medicines
Cetirizine 10 mg tabletsAdults and adolescents aged 12 years and over take 10 mg orally once daily, with renal dose adjustment according to the SmPC.
Adrenaline auto-injector 300 microgramsAdults at risk use one 300 microgram intramuscular auto-injector into the outer thigh at anaphylaxis onset and call emergency services; use a second after five minutes if not improving.