# Anaphylaxis in Children

> Anaphylaxis in children for NEET-PG Paediatrics: diagnostic criteria, IM adrenaline 0.01 mg/kg dosing, biphasic reactions and autoinjector use.

- Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/anaphylaxis-children
- Exam / course: NEET-PG · Subject: Paediatrics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-02
- Last updated: 2026-10-02
- How to cite: "Anaphylaxis in Children", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/anaphylaxis-children

## Direct answer

Anaphylaxis kills by delayed adrenaline, not by diagnostic doubt: a child with acute onset of urticaria or angio-oedema plus respiratory compromise (stridor, wheeze, distress) or circulatory collapse meets criteria, and so do two-system reactions and hypotension after a known allergen — treatment starts the moment criteria register, before any investigation. The drug is intramuscular adrenaline 0.01 mg/kg of 1:1000 solution into the anterolateral thigh, maximum 0.3 mg in children, repeated every 5-15 minutes if response is inadequate, child flat with legs raised. Foods dominate paediatric triggers in India — cow's milk and egg in the young, peanuts and tree nuts later — with drugs, venom and contrast media following; refractory cases get an adrenaline infusion. Observation must extend six to twelve hours (longer in severe or asthmatic children) for biphasic reactions, and every survivor leaves with an action plan, adrenaline autoinjector training and trigger identification.

## What you must remember

- **Diagnostic criteria verbatim:** acute skin or mucosal involvement plus respiratory compromise or hypotension; OR two or more systems after likely allergen; OR hypotension after known allergen — one pathway suffices.
- **Adrenaline ampoule arithmetic:** 1:1000 means 1 mg in 1 mL; dose 0.01 mL/kg (0.01 mg/kg) intramuscularly, maximum 0.3-0.5 mg — a 15 kg child receives 0.15 mL (0.15 mg).
- **Route, site and position:** intramuscular into the vastus lateralis beats subcutaneous and deltoid for speed and peak levels, and never delay for intravenous access; keep the child supine with legs elevated (sitting up suddenly can kill — empty inferior vena cava syndrome), pregnant women left lateral, breathing difficulty semi-recumbent.
- **Refractory pathway:** 20 mL/kg crystalloid boluses for shock, repeat adrenaline doses, then infusion (about 0.1-1 microgram/kg/min titrated); glucagon (20-30 micrograms/kg) bypasses the beta-blocked receptor; nebulised adrenaline and salbutamol are adjuncts, never substitutes.
- **Second-line drugs are decorative:** antihistamines relieve urticaria only, corticosteroids have no proven acute role (possibly small biphasic protection), and neither prevents death — "hydrocortisone first" is the mark-losing answer.
- **Biphasic reaction discipline:** up to about one in twenty rebound within 1-72 hours (most within 8-12); observe at least 6-12 hours, longer after severe reactions.
- **Discharge package:** two autoinjectors (0.15 mg for 15-25 kg, 0.3 mg above 25-30 kg), written action plan, parent and school training, and allergology referral.
- **Indian trigger profile:** cow's milk, egg, wheat and pulses (chickpea, lentil) dominate Indian paediatric series — not the Western peanut-centric list.

## Running the first ten minutes

A four-year-old, 16 kg, develops widespread urticaria, vomiting, hoarseness and a barking cough ten minutes after a nut-containing sweet. Minute zero: recognise two-system involvement, call for help, lay the child flat, draw up 0.16 mL of 1:1000 adrenaline (0.01 mg/kg for 16 kg) and inject into the thigh; monitoring on, oxygen by mask, saline bolus prepared. Minutes two to five: reassess — improving hoarseness and fading urticaria mean response; persistent stridor means repeat adrenaline and escalate. Minutes five to ten: if two or three doses fail to hold, start an adrenaline infusion in a monitored bed, add nebulised adrenaline for airway oedema and salbutamol for wheeze, and plan intensive care. Throughout: no antihistamine-first reflexes, no sitting upright, no subcutaneous route; intravenous adrenaline only by infusion pump. After stabilisation: six to twelve hours of observation, allergology referral, two autoinjectors with training for parents and school, and a written plan in the local language. The preventive logic closes the loop: uncontrolled asthma is the strongest modifier of fatal food anaphylaxis, so asthma control is part of anaphylaxis management.

## Where students slip

Dose-format confusion leads the error list: 1:1000 versus 1:10,000 swap under pressure — intramuscular use always takes 1 mg/mL (1:1000); 1:10,000 is the diluted intravenous preparation. Second, hydrocortisone placed first in sequences; it does nothing acutely — adrenaline intramuscularly, repeated early, saves the child. Third, the observation window cut short — discharge at two hours ignores the biphasic rebound, and examiners time the vignette to catch it. Fourth, forgetting the milk-and-egg profile of Indian paediatric triggers; not every Indian exam stem is peanut.

## Frequently asked questions

### What is the intramuscular adrenaline dose in a child?

0.01 mg/kg of 1:1000 (1 mg/mL) solution into the anterolateral thigh, maximum 0.3 mg per dose in children, repeated every 5-15 minutes for inadequate response.

### What clinical criteria diagnose anaphylaxis at the bedside?

Skin or mucosal involvement plus respiratory compromise or hypotension, or two-system involvement after likely allergen exposure, or hypotension after a known allergen.

### Why must antihistamines and steroids not delay adrenaline?

They have no role in reversing airway oedema or shock — adrenaline is the only first-line drug, and any delay increases mortality; antihistamines only soothe urticaria.

### What is a biphasic reaction and how long should observation last?

Recurrence of symptoms within 1-72 hours (usually 8-12) after full recovery, seen in up to about one in twenty children — observe at least 6-12 hours, longer after severe reactions.

### Which autoinjector strength is prescribed, and for whom?

Generally 0.15 mg for children of 15-25 kg and 0.3 mg above 25-30 kg (brand-dependent), always as two units with training for family and school.