How long anaphylaxis can last

The course depends on the trigger, how exposure occurred, how quickly adrenaline was given and how the body responds. Breathing, skin, gut and circulation symptoms do not always settle together. Some features fade promptly while others need repeated treatment and monitoring.

A second wave of symptoms can develop after the first episode appears to have resolved, without another exposure. That possibility is why feeling better after an injector does not mean it is safe to remain at home. The emergency team determines an appropriate observation period from the reaction's severity and response.

Give prescribed adrenaline immediately when anaphylaxis is suspected and call emergency services, even if improvement follows. Keep the person lying flat without walking. If breathing is hard, they may sit with legs extended; if unconscious but breathing, turn them onto their side and monitor them closely.

Follow the written allergy plan and dispatch instructions if symptoms fail to settle or return. Do not use antihistamines as a replacement for adrenaline, and do not leave the person alone. If they become unresponsive and are not breathing normally, begin cardiopulmonary resuscitation if you know how and follow dispatcher coaching.

Any suspected anaphylaxis needs emergency help. Red flags include throat or tongue swelling, breathing difficulty, wheezing, a hoarse voice, sudden faintness, confusion, collapse, or pale, blue or grey colour. Reappearance of any severe symptom after initial recovery is another emergency.

Hospital clinicians can watch the airway, breathing and circulation, provide further treatment and decide when discharge is safe. Before leaving, make sure you understand what to do if symptoms return and how to replace any auto-injector that was used.

Review the timing of exposure, each symptom, the treatment given and whether symptoms returned. Ask about referral for allergy assessment, avoiding the suspected trigger, obtaining replacement injectors, and sharing an emergency plan with family, school or work contacts.