Anaphylaxis: Emergency Response
A severe, rapid-onset allergic reaction affecting breathing or circulation.
Last revised
Key takeaways
- Only effective treatment: intramuscular adrenaline into the outer thigh
- Second dose: after 5 minutes if no improvement
- Most useful single change: Use the auto-injector immediately at the first sign.
- Commonest mistake: Standing the person up or letting them walk, which can be fatal.
- See a doctor if any of the signs under "When to get help" below apply to you.
Why it matters
Adrenaline is the only treatment and delay is the main cause of death, so recognition and speed are the entire issue.
The numbers, in one place
| Measure | Figure |
|---|---|
| Only effective treatment | intramuscular adrenaline into the outer thigh |
| Second dose | after 5 minutes if no improvement |
| Position | lie flat with legs raised; sit up only if breathing is difficult |
| Antihistamines | do not treat it and must never delay adrenaline |
What helps
- Use the auto-injector immediately at the first sign
- Call 999 straight after
- Lie the person flat with legs raised
What to avoid
- Standing the person up or letting them walk, which can be fatal
- Waiting to see whether symptoms settle
Where to go next
- What People Get Wrong About Anaphylaxis: Emergency Response
- Anaphylaxis: Emergency Response: A Beginner-Friendly Start
- What the Guidance Really Says About Suspected Stroke
- Suspected Heart Attack: Sorting the Evidence From the Noise
When to get help
Call 999 immediately for swelling of the lips, tongue or throat, difficulty breathing or swallowing, a hoarse voice, wheeze, widespread rash with faintness, or collapse. Use adrenaline first, then call. Always go to hospital even if symptoms resolve, because they can return hours later.
Where this comes from
- Resuscitation Council UK — anaphylaxis
- NHS — Anaphylaxis
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarised or generalised beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.