Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Anaphylaxis and adrenaline autoinjector plans
Paediatrics and child health · UK scope · Sources checked 27 Aug 2026 · Clinical review pending
!
Suspected anaphylaxis
Sudden airway, breathing or circulation compromise after likely allergen exposure is anaphylaxis; skin or mucosal changes support diagnosis but may be absent.
Action: Call for help, remove the trigger when feasible, lay the child flat with legs raised unless breathing requires a supported sitting position, give intramuscular adrenaline into the anterolateral thigh and repeat after five minutes if dangerous features persist.
Overview
Recognise anaphylaxis without waiting for skin signs, give correctly concentrated intramuscular adrenaline promptly, manage refractory physiology and discharge children with specialist referral and a rehearsed auto-injector plan.
Use the RCUK ABCDE approach and treat the clinical syndrome. Airway problems include tongue or throat swelling, hoarseness and stridor; breathing problems include persistent cough, wheeze, tachypnoea, exhaustion and hypoxia; circulation problems include pallor, hypotension, collapse and altered consciousness. Skin signs strengthen recognition but are absent in a minority.
Adrenaline works through alpha-mediated vasoconstriction and oedema reduction and beta-mediated bronchodilation and cardiac support. Give it intramuscularly into the outer mid-thigh using 1 mg/mL solution. Time the dose and repeat at five minutes for persisting airway, breathing or circulation features. There are no absolute contraindications to IM adrenaline in true anaphylaxis.
Position changes matter. A child with hypotension should lie flat with legs raised; sudden standing can cause fatal empty-ventricle collapse. A child struggling to breathe may sit with legs extended, while an unconscious breathing child is placed in recovery position.
Practice
Two practice questions
Your practice draft is saved in this browser.
Question 1 of 2
0 correct
Paediatrics and child healthOriginal SBA
First emergency medicine
A seven-year-old develops wheeze, hoarse voice and dizziness minutes after eating a biscuit. Which medicine should be given first?
Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources
Sources and review status
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Support severe reactions with high-flow oxygen, continuous ECG, saturation and blood pressure monitoring, and early IV or intraosseous access. Give isotonic crystalloid 10 mL/kg rapidly for shock and reassess. Nebulised bronchodilator may supplement adrenaline for persistent wheeze, but asthma treatment alone is inadequate when anaphylaxis is present.
Refractory anaphylaxis means persisting dangerous physiology despite two appropriate IM doses. Obtain critical-care and anaesthetic help and begin a low-dose IV adrenaline infusion through the specialist protocol with continuous monitoring; IV bolus adrenaline is not routine. Consider ongoing allergen absorption, severe asthma, tension pneumothorax and alternative shock diagnoses.
After recovery, document suspected trigger, timing, clinical criteria, every treatment and response. NICE recommends specialist allergy referral. Tryptase sampling is most useful after venom, medicine or idiopathic reactions, ideally as soon as possible after emergency treatment and again within one to two hours, no later than four hours, with a later baseline arranged by allergy services. In children under 16, food-triggered reactions usually do not require acute tryptase.
An auto-injector plan names the child's device dose, trigger-avoidance strategy and symptoms requiring use. Train the child, family, school and carers to remove the safety cap, press into the outer thigh through clothing if necessary, hold for the brand-specified time, call 999 and give the second device after five minutes if not improving. Devices must travel with the child, not remain locked in an office.
Key points
Diagnose anaphylaxis clinically from sudden airway, breathing or circulation compromise, usually with skin or mucosal change; never wait for rash before treating dangerous physiology.
Intramuscular adrenaline is first-line: use 1 mg/mL solution, give 10 micrograms/kg into the anterolateral thigh, maximum 500 micrograms, and repeat after five minutes if needed.
When an exact weight is unavailable, RCUK age doses are 100–150 micrograms below six months, 150 micrograms from six months to six years, 300 micrograms from six to 12 years and 500 micrograms over 12 years.
Lay the child flat with legs raised; allow supported sitting for severe breathing difficulty, recovery position if unconscious and pregnant patients on the left side, but do not allow standing or walking.
Give high-concentration oxygen for critical illness, obtain monitoring and intravenous or intraosseous access and use a rapid 10 mL/kg crystalloid bolus for shock, reassessing for repeat fluid.
Antihistamines treat persistent skin symptoms only after airway, breathing and circulation recovery; corticosteroids are not routine emergency treatment and do not replace adrenaline.
After two appropriate intramuscular doses with persistent dangerous features, start an intravenous adrenaline infusion only through an expert monitored refractory-anaphylaxis protocol.
Aetiology
01
Food-triggered anaphylaxis
Peanut, tree nut, milk, egg, sesame, fish, shellfish and other foods are the most frequent childhood community triggers.
02
Medicine or venom trigger
Antibiotics, perioperative agents, NSAIDs, vaccines rarely, and bee or wasp venom can provoke systemic immediate hypersensitivity reactions.
03
Idiopathic or mast-cell disorder
Some episodes lack an identified allergen, while recurrent severe or baseline-tryptase elevation can indicate clonal or hereditary mast-cell disease.
04
Cofactor amplification
Exercise, infection, asthma, NSAIDs and other cofactors lower reaction threshold or increase severity after an otherwise tolerated exposure.
Pathophysiology
1
Systemic mediator release
Mast-cell and basophil activation releases histamine, tryptase, leukotrienes and cytokines across several organ systems within minutes.
2
Airway and bronchial obstruction
Laryngeal mucosal oedema, bronchoconstriction and mucus rapidly narrow airflow and create stridor, wheeze, cough and hypoxaemia.
3
Distributive hypovolaemic shock
Vasodilation and capillary leakage reduce vascular resistance and circulating volume, causing hypotension, poor perfusion and collapse.
4
Biphasic inflammation
Symptoms can recur after initial resolution without re-exposure, particularly after severe reactions or delayed and repeated adrenaline need.
Clinical features and red flags
Airway anaphylaxis
Rapid tongue or throat swelling, hoarseness, stridor or difficulty swallowing after exposure indicates upper-airway compromise.
Breathing anaphylaxis
Persistent cough, wheeze, tachypnoea, hypoxia or exhaustion after likely allergen exposure indicates lower-airway involvement.
Circulatory anaphylaxis
Hypotension, collapse, confusion, pallor or reduced responsiveness reflects distributive and hypovolaemic shock requiring immediate adrenaline.
Skin supportive features
Generalised urticaria, flushing and angioedema support anaphylaxis but neither their presence nor absence alone defines severity.
Refractory reaction
Persistent airway, breathing or circulation impairment after two correctly timed intramuscular doses requires expert infusion-based escalation.
1Call for help, stop the trigger if feasible and position the child safely without standing.
2Give 1 mg/mL adrenaline intramuscularly into the anterolateral thigh and start monitoring.
3Repeat after five minutes if dangerous features persist while supporting oxygenation and circulation.
02SupportRestore breathing and circulationFirst lineHypoxia, bronchospasm or shock continues during first-line treatment.+
1Give high-concentration oxygen and obtain intravenous or intraosseous access without delaying adrenaline.
2Administer 10 mL/kg isotonic crystalloid rapidly for shock and reassess for further fluid.
Complications
01
Hypoxic cardiac arrest
Untreated airway obstruction, bronchospasm and shock can progress rapidly to cardiac arrest, especially when adrenaline is delayed.
02
Biphasic reaction
Recurrent symptoms after apparent resolution require renewed emergency assessment and justify observation based on individual risk factors.
03
Adrenaline dosing error
Confusing 1 mg/mL with dilute intravenous preparations or using an intravenous bolus can cause severe hypertension, arrhythmia and injury.
04
Future accidental exposure
Absent referral, inaccessible devices or poor school training leaves the child vulnerable to delayed treatment during the next reaction.
Monitoring and follow-up
Record exact times of symptom onset, adrenaline doses, fluids, physiological response and complete resolution.
Observe in an age-appropriate paediatric setting for a duration based on severity, dose requirement, asthma, biphasic history, supervision and access to care.
Check each prescribed auto-injector brand, strength, expiry, carriage and technique before discharge and at follow-up.
Ensure asthma is controlled and inhalers are accessible without presenting bronchodilator as a substitute for adrenaline.
Confirm allergy referral, baseline tryptase plan when indicated and written communication to primary care and school.
Review future reactions, avoidance burden, anxiety and whether every caregiver can recognise airway, breathing and circulation features.
Special situations
Skin can be absent
A child can have fatal respiratory or circulatory anaphylaxis without urticaria, especially during rapidly progressive reactions.
Position is an intervention
Standing after apparent improvement can abruptly reduce venous return and precipitate collapse in vasodilated hypovolaemic physiology.
Concentration causes errors
The intramuscular solution is 1 mg/mL; confusing it with dilute intravenous preparations creates tenfold dosing hazards.
Tryptase has a clock
Timed acute and later baseline samples can support diagnosis, but adrenaline always precedes blood sampling.
The second device is planned
Two-device access allows a correctly timed repeat while ambulance help is coming rather than encouraging unstructured repeated dosing.
Common pitfalls
01
Waiting for urticaria before giving adrenaline.
02
Using antihistamine as first-line anaphylaxis treatment.
Sampling tryptase before treating dangerous physiology.
07
Discharging without two-device access, training and referral.
Serum tryptase can support later investigation in selected severe, venom, medicine or idiopathic reactions, but sampling never delays treatment and a normal result does not exclude food anaphylaxis.
Before discharge, refer to specialist allergy, prescribe the correct auto-injector devices, train with the actual brand, provide a written plan and ensure the child has access to two devices.
Observation is individualised by severity, treatment response, comorbidity, biphasic risk, supervision and access to emergency care; children should be managed in an appropriate paediatric setting.
Persistent airway, breathing or circulation problems after two intramuscular adrenaline doses defines refractory anaphylaxis and needs expert intravenous adrenaline infusion and critical care.
Beta-blocker exposure, mast-cell disease, severe asthma, delayed adrenaline or a continuing absorbed allergen increases severity and biphasic risk.
Skin signs are absent in some anaphylaxis episodes, while skin signs alone without airway, breathing or circulation compromise do not automatically define anaphylaxis.
A child treated for anaphylaxis needs paediatric observation, specialist allergy referral, injector provision and training before discharge, not simple antihistamine advice.
explain every episode.
05Baseline mast-cell evaluation
Why
Investigate recurrent severe, hypotensive or apparently idiopathic anaphylaxis when baseline tryptase or phenotype is concerning.
Interpretation and limitations
Allergy specialists interpret baseline tryptase, hereditary alpha-tryptasaemia and clonal-disease testing in context.
3Use inhaled bronchodilator as an adjunct for wheeze and prepare early airway expertise.
03RefractoryEscalate after two dosesEscalationAirway, breathing or circulation problems persist after two intramuscular adrenaline doses.+
1Call anaesthesia and critical care and confirm dose, concentration, timing and diagnosis.
2Start monitored intravenous adrenaline infusion through the refractory-anaphylaxis protocol.
3AlternativeSearch ongoing allergen absorption, severe asthma and alternative obstructive or shock causes in parallel.
04DischargePrevent and rehearse recurrence careSymptoms have resolved and observation confirms a safe recovery trajectory.+
1Refer every child for specialist allergy assessment and document trigger and treatment precisely.
2Supply the prescribed auto-injectors, written plan and hands-on device training before discharge.
3Agree observation, school access, two-device carriage and emergency follow-up based on individual risk.
Key medicines and prescribing safety3 treatments · regimens, roles and cautions+
First-line life-saving treatment for suspected anaphylaxis, reversing vasodilation, capillary leak, mucosal oedema and bronchoconstriction.
Intramuscular adrenaline
Give 10 micrograms/kg using 1 mg/mL adrenaline into the anterolateral thigh, maximum 500 micrograms; if weight is unavailable use the RCUK age-based dose and repeat after 5 minutes when airway, breathing or circulation problems persist.
Do not delay for antihistamine, cannulation or certainty; verify the 1 mg/mL concentration, avoid routine intravenous bolus use and monitor rhythm and perfusion while treating severe physiology.
Immediate community delivery of intramuscular adrenaline by the child, family, school or another trained carer.
Adrenaline auto-injector
Use the exact brand and strength prescribed from the child's weight and specialist plan; administer one device into the outer mid-thigh immediately for anaphylaxis, call 999 and use the second device after 5 minutes if dangerous symptoms persist.
Prescribe access to two in-date devices, train with the actual brand because activation and hold times differ, replace after use and never store them locked away or at temperature extremes.
Restores intravascular volume lost through profound vasodilation and capillary leakage while adrenaline treats the underlying physiology.
Isotonic crystalloid
Give 10 mL/kg intravenously or intraosseously as a rapid bolus for anaphylactic shock, reassess circulation immediately and repeat under senior resuscitation guidance because large volumes may be required.
Do not let cannulation delay intramuscular adrenaline; reassess lungs, perfusion and response after each bolus and use critical-care support for persistent shock.