Anaphylaxis is rare but fast. A child can go from mild itching around the mouth after eating a cashew to struggling to breathe within minutes. The parents who manage it best are those who have rehearsed the steps in advance, who know exactly where both auto-injectors are, and who understand that adrenaline is given first — before antihistamines, before waiting to see if things improve on their own.
The hesitation to use an auto-injector when unsure is understandable, but the risk-benefit is heavily weighted toward acting early. Adrenaline given in error to a child who turns out not to be having anaphylaxis is very unlikely to cause harm. Adrenaline given too late to a child who is having anaphylaxis can be the difference between life and death.
Healthbooq (healthbooq.com) covers allergy and emergency health in children.
What Anaphylaxis Is
Anaphylaxis is a severe systemic allergic reaction affecting multiple organ systems simultaneously. It is caused by the massive release of histamine and other inflammatory mediators from mast cells after exposure to a trigger antigen in a sensitised individual. This causes vasodilation, increased vascular permeability, smooth muscle contraction, and excess mucus production — collectively resulting in the features that define anaphylaxis.
The Resuscitation Council UK defines anaphylaxis as likely when a patient develops a sudden illness (usually within minutes of exposure to an allergen) involving one or more of: life-threatening airway and/or breathing and/or circulation problems, and usually skin and/or mucosal changes. Most cases involve two or more body systems simultaneously.
Triggers in Children
In children, the most common triggers are foods. Peanuts and tree nuts (cashew, walnut, pistachio, Brazil nut) are the most frequent. Milk and egg are significant in younger children. Fish, shellfish, sesame, and wheat also account for cases. Insect stings (bee and wasp) are the second most common category. Drug allergy (including penicillin and NSAIDs like ibuprofen) accounts for some cases.
Important: the severity of a reaction to a particular allergen can vary from exposure to exposure. A child who has previously had only mild reactions is not protected from a severe future reaction. This is why all children with confirmed food allergy causing systemic symptoms should be prescribed adrenaline auto-injectors.
Recognising Anaphylaxis
Urticaria (hives) and angioedema are extremely common allergic reactions that do not constitute anaphylaxis alone. The critical distinction is whether life-threatening features are developing.
Airway features: throat tightening, stridor, hoarse voice, difficulty swallowing, drooling. The child may point to their throat.
Breathing features: wheeze, shortness of breath, increased respiratory rate, oxygen desaturation. In young children, look for intercostal recession and nasal flaring.
Circulation features: pallor, clamminess, tachycardia, faintness, loss of consciousness. Hypotension may develop. Young children may become limp.
Skin features: urticaria, angioedema, erythema, generalised flushing. Present in most but not all cases — absence of skin features does not exclude anaphylaxis.
Gut features: nausea, vomiting, abdominal cramping. Can be an early warning sign.
A key principle: anaphylaxis can present without prominent skin features, particularly with sting-triggered and exercise-triggered reactions. Sudden circulatory collapse with a known allergen exposure is anaphylaxis until proven otherwise.
What Not to Do
Antihistamines treat urticaria. They do not treat anaphylaxis. They work too slowly, do not address bronchospasm, and do not prevent cardiovascular collapse. Giving antihistamines instead of adrenaline wastes critical time.
Oral steroids also do not work quickly enough for acute anaphylaxis, though they are given later in hospital to reduce the risk of biphasic reaction.
Do not have the child stand up or sit upright if they are feeling faint — lie them down with legs raised (or sit them upright only if they have respiratory distress making lying down difficult). Sudden standing causes a dangerous drop in blood pressure.
Using an Adrenaline Auto-Injector
The three auto-injector brands available in the UK are EpiPen, Emerade, and Jext. They all deliver 300 micrograms of adrenaline for children over 30kg (or children under 30kg may be prescribed 150 microgram devices). The technique varies slightly by device; families should be trained specifically on their prescribed device.
General principles: remove the safety cap, hold the device firmly, and jab the tip firmly against the outer mid-thigh, through clothing if necessary. Hold in place for ten seconds. The injection can be given through jeans or leggings. Remove and massage the site briefly.
Call 999 immediately before or after injecting. Do not wait to see if the first dose works before calling for help. If symptoms do not improve or worsen after five minutes, a second auto-injector can be given. This is why two devices should always be carried.
After injection, the child should be taken to hospital by ambulance even if the reaction appears to have resolved completely. Biphasic reactions — a second wave of anaphylaxis occurring hours after the first — occur in up to 20 per cent of cases. Hospital observation for a minimum of four to six hours after severe anaphylaxis is standard.
Allergy Action Plans
Every child prescribed an adrenaline auto-injector should have a personalised allergy action plan prepared by their allergy team, specifying their known allergens, what symptoms to treat with antihistamine, what symptoms require adrenaline, and when to call 999. The plan should be shared with the school, childminder, and any other regular caregivers.
Anaphylaxis UK and the British Society for Allergy and Clinical Immunology (BSACI) both provide template plans and further resources.
Key Takeaways
Anaphylaxis is a severe, life-threatening allergic reaction that requires immediate treatment with adrenaline (epinephrine). In children, the most common triggers are foods (peanuts, tree nuts, milk, egg, fish, sesame), insect stings, and medications. The key feature is involvement of at least two body systems simultaneously. Antihistamines treat hives but do not treat anaphylaxis and should not delay adrenaline. Adrenaline auto-injectors (EpiPen, Emerade, Jext) should be given into the outer mid-thigh and held for ten seconds. Two auto-injectors should always be carried. After any use, the child must go to hospital by ambulance even if they appear to have recovered, because biphasic reactions can occur hours later.
