Adrenaline for anaphylaxis: what you need to know

It helps reverse airway swelling, breathing difficulty and a dangerous fall in blood pressure. Antihistamines may ease some skin symptoms, but they do not replace adrenaline when anaphylaxis is suspected.

Anaphylaxis is a rapidly developing allergic reaction that can affect more than one body system. A person may develop throat or tongue swelling, a hoarse voice, wheezing, difficult breathing, dizziness, collapse, or a combination of skin and digestive symptoms after contact with a trigger.

Injected adrenaline tightens widened blood vessels, supports blood pressure, relaxes muscles around the airways and reduces swelling. It is normally injected into the outer mid-thigh, through clothing if necessary, by following the device instructions.

Use the prescribed auto-injector as soon as anaphylaxis is suspected, then call local emergency services and say that the person may have anaphylaxis. Note the time the dose was given. If symptoms do not improve or return and another prescribed device is available, follow the person's emergency plan and the device instructions.

Keep the person lying flat with their legs raised when possible. If breathing is difficult, they may sit with their legs extended; if unconscious but breathing, place them on their side. Do not let them stand or walk suddenly. Begin resuscitation if they stop breathing and you are able to do so.

Treat sudden breathing difficulty, throat or tongue swelling, collapse, marked dizziness, or rapidly worsening symptoms after a possible allergen exposure as an emergency. Use adrenaline first if it is available; do not delay it while waiting for help or while looking for an antihistamine.

Emergency assessment is required even when the person feels better after the injection because symptoms can recur and further treatment or observation may be needed. If you are unsure whether the device fired correctly, tell the emergency team and bring the used device with you.

Ask which symptoms in your personal emergency plan should trigger adrenaline, how to position the person safely, and when a further prescribed dose should be used. Request a demonstration with a trainer device and make sure family members, carers or school staff can recognise the correct pen and follow its instructions.

Discuss likely triggers, allergy testing when appropriate, replacement of used or expired devices, and storage away from damaging heat or cold. Check the viewing window and expiry date regularly, and arrange a replacement if the liquid looks discoloured or contains particles.