What should you know about biphasic anaphylaxis symptoms?

Anaphylaxis is a severe, fast-moving allergic reaction. In a biphasic pattern, symptoms settle and then return without a new exposure. The second phase can affect the skin, breathing, circulation, or digestion. Early improvement does not prove the danger has ended, because symptoms can recur after initial treatment and observation. Food allergy, medicines, insect stings, and other triggers can cause anaphylaxis.

If anaphylaxis is suspected, use the prescribed adrenaline auto-injector immediately and call emergency services. Lay the person down with legs raised unless breathing is easier sitting; keep them still and warm. A person who is vomiting or unconscious should be placed on their side. Do not let them stand or walk, and do not rely on antihistamines for breathing or circulation problems.

Emergency help is needed for wheezing, throat or tongue swelling, difficulty speaking, faintness, collapse, severe abdominal symptoms, or rapidly spreading hives after an exposure. Anyone whose anaphylaxis has improved but develops new symptoms needs reassessment in hospital. Do not drive yourself or remain alone during a possible recurrence.

Ask what trigger is suspected, how long observation should continue, how to use the auto-injector, whether you need allergy testing, and how to create a written emergency plan.