UrgentEmergency Guide
Hives: Red Flags & Emergency Signs
Hives (urticaria) with throat swelling, breathing difficulty, or low blood pressure constitutes anaphylaxis — the adrenaline auto-injector must be used immediately.
🚨 Call 999 / 112 Immediately
- ⚠Hives with throat tightness, tongue swelling, or stridor — anaphylaxis (IM adrenaline 0.5mg, 999)
- ⚠Hives with hypotension and collapse after food, drug, or insect sting — anaphylactic shock
- ⚠Hives spreading rapidly across the entire body within minutes — systemic allergic reaction
⚡ See a Doctor Today
- •Hives with facial swelling (angioedema) — may progress to airway involvement
- •Hives lasting more than 6 weeks — chronic urticaria (investigate for autoimmune cause)
High-Risk Combinations
When hives occurs together with any of these symptoms, urgency increases significantly:
Conditions to Rule Out Urgently
Anaphylaxisemergency
IM adrenaline 0.5mg thigh; 999; lie flat (unless breathless); repeat at 5 min if no response
Condition Authority Pages
Differential diagnosis analyses:
When to Call Emergency Services
- →Hives with any breathing difficulty or throat swelling
- →Known anaphylaxis — use auto-injector and call 999 simultaneously