Anaphylaxis & Severe Allergic Reaction
Anaphylaxis can close the airway within minutes. Adrenaline into the outer thigh is the only treatment that reverses it, and it must not be delayed.
When to call an ambulance immediately
- Swelling of the lips, tongue, throat or face
- Difficulty breathing, noisy breathing, wheeze, or a hoarse voice
- A tight throat, or a feeling that the throat is closing
- Sudden widespread hives or flushing with any breathing or circulation symptom
- Dizziness, collapse, or pale clammy skin suggesting a falling blood pressure
- Persistent vomiting or severe abdominal pain after a known trigger
What to do
Work through these in order. If you are alone, put your phone on speaker so the 108 call handler can guide you while your hands stay free.
- 1
Give adrenaline first, without hesitating
If an adrenaline auto-injector is available, use it immediately into the outer mid-thigh. It works through clothing. Hold it in place as the device instructs, usually about three seconds, then remove it and note the time. Delay in giving adrenaline is the factor most consistently associated with deaths from anaphylaxis.
- 2
Call 108 and say the word anaphylaxis
Every person who receives adrenaline needs hospital assessment, even if they recover completely, because symptoms can return hours later.
- 3
Position them correctly
Lie them flat with the legs raised if they feel faint or the blood pressure is dropping. If they are struggling to breathe, let them sit up. If they are pregnant, lie them on their left side. If unconscious but breathing, use the recovery position.
- 4
Remove the trigger if you can do so safely
Stop any drug infusion. Scrape a bee sting sideways off the skin rather than pinching it, which squeezes in more venom. Do not make them vomit a food trigger.
- 5
Give a second dose after 5 minutes if needed
If there is no improvement or symptoms return, give a second adrenaline dose into the other thigh using a fresh device.
- 6
Be ready to start CPR
If they become unresponsive and stop breathing normally, begin chest compressions immediately.
Never do these
Most of these are well-intentioned and widely believed. All of them make the situation worse.
- Never stand the person up or walk them to a vehicle. Sudden upright posture during anaphylaxis has caused cardiac arrest.
- Never rely on cetirizine, chlorpheniramine or any antihistamine to treat anaphylaxis. They do nothing for airway swelling or blood pressure.
- Never wait to see whether it improves on its own before giving adrenaline. There is no benefit in waiting and a real cost.
- Never assume a mild previous reaction predicts a mild next one. Severity is unpredictable.
- Never send them home after adrenaline. Biphasic reactions can occur several hours later.
Once the immediate danger has passed
- Take the used auto-injector to hospital so the team knows the dose and timing.
- Ask for a prescription for two replacement auto-injectors before discharge, and for referral to an allergy specialist.
- Write down exactly what was eaten, taken or contacted in the hours beforehand.
Frequently asked
Can I give adrenaline if I am not sure it is anaphylaxis?
Yes. Intramuscular adrenaline in the thigh at the standard dose is very safe, even when given to someone who turns out not to have anaphylaxis. The risk of withholding it is far greater than the risk of giving it.
What are the common triggers in India?
Peanuts and tree nuts, shellfish and fish, milk and egg in children, wheat, insect stings, and drugs, especially penicillins and painkillers such as diclofenac. Contrast dye used in scans is another.
Reviewed and written by
Dr. Poonam Sekhon Chahal, MBBS, MEM
Senior Emergency Physician, Manipal Hospital, Patiala · Certified in ACLS, ATLS, PALS and PoCUS