Paeds · clinical-pharmacology-and-therapeutics
Poisoning antidotes and toxicology pharmacology
Also known as Paediatric antidotes pharmacology · NAC acetylcysteine for paracetamol poisoning · Naloxone for opioid toxicity · Snake antivenom in children · Chelation therapy deferoxamine succimer · Toxidromes and antidote mechanisms
A fellowship approach to poisoning antidotes and toxicology pharmacology in children, covering the four mechanism classes of antidote, the toxidrome-driven bedside assessment, N-acetylcysteine for paracetamol poisoning, naloxone for opioid-induced respiratory depression, snake and other antivenoms, and chelation therapy for iron and lead. It gives weight-based doses and routes, the receptor, substrate, and binding mechanisms each antidote exploits, and the monitoring and pitfalls of reversing a toxin in a child.
On this page
Study tools
Your progress
Saved on this device.
Practise this topic
Target exams
Red flags
- A child with a reduced respiratory rate, small pupils, and falling level of consciousness after an opioid or recreational drug — give naloxone titrated to respiratory rate, do not wait for cyanosis
- A staggered or time-unknown paracetamol ingestion, or any ingestion above the 150 mg/kg treatment line — start N-acetylcysteine and treat as hepatotoxic until the plot proves otherwise
- A child with systemic snake-envenomation signs — coagulopathy, neurotoxicity, myotoxicity, or haemodynamic collapse — give species-appropriate antivenom early rather than waiting for laboratory confirmation
- An iron ingestion with vomiting, lethargy, metabolic acidosis, or shock — measure the serum iron and start IV deferoxamine when toxicity is present, because the window to chelate closes as the metal distributes
- Flumazenil given to a child who chronically takes benzodiazepines — it can precipitate refractory seizures and is not a routine reversal agent
Life stages
Care settings
Clinical exam formats
Board mappings
- General and Community Paediatrics
- Acute and Emergency Care
- Current 2026 PREP curriculum — Learning Objective 2.2.1: Recognise, prioritise and manage an acutely ill infant, child or young person, including poisoning and antidote therapy
- Current 2026 PREP curriculum — Learning Objective 2.4.4: Assess and manage infants, children and young people requiring safe prescribing of medicines, including antidotes
- Renewed curriculum for first-year trainees from 2027 — Learning goal 6: Clinical management, essential general paediatrics and acute toxicology
- Clinical Applications
- Medical Sciences
- Long Cases
- Short Cases
- 4. Professional skills and knowledge: Patient management
- 7. Patient safety, including safe prescribing of antidotes
- 8. Quality improvement and patient safety
- Foundation of Practice (FOP)
- Theory and Science (TAS)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
- Communication
- General Pediatrics Content Outline — Domain 10: Principles of Pharmacology and Medication Management
- General Pediatrics Content Outline — Universal Task 4: Management and Treatment, including acute poisoning
- Systems-Based Practice 1: Coordination of Care and Safe Prescribing
- Patient Safety/Quality Improvement 1: Medication Safety and Toxicology Governance
- Medical Expert
- Collaborator
- Pediatrics: Core EPA #5 — Recommending and Initiating Pharmacologic Interventions
Overview & Definition
A toddler who has drunk grandma's iron tablets, a teenager unconscious from an opioid, a country child bitten by a brown snake — these are the children whose survival turns on a single substance given at the right moment. An antidote is a medicine that counteracts a specific toxin by a defined pharmacological mechanism, and although few poisoned children need one, the child who does needs it without delay. The paediatric pharmacology of antidotes is therefore the science of matching a poison to its reversal agent by weight, route, mechanism, and timing, layered on the bedrock of airway, breathing, and circulation. [3] [8]
The discipline sits between the clinical toxicology topics — paracetamol poisoning, iron and salicylate poisoning, opioid and recreational drug toxicity, and envenomation — which carry the full management of each toxin, and the general prescribing topics which carry dose calculation and medication safety. This hub distils what is common across them: how antidotes work, how to dose them in a child, how to choose among them at the bedside, and how to monitor and avoid their own harms. A fellowship candidate must hold four mechanism classes, five named antidotes with their weight-based doses, and the toxidrome pattern that triggers each one. [1] [3]
The reason mechanism matters is that an antidote is not a generic antidote. Naloxone reverses an opioid because it competes for the mu-receptor; it does nothing for a benzodiazepine or an iron tablet. N-acetylcysteine works for paracetamol because it replenishes the glutathione that the toxic metabolite consumes; it does nothing for a snakebite. Deferoxamine binds iron atom-for-atom and is useless against lead, which needs succimer or EDTA. The candidate who reaches for an antidote without naming its mechanism is reaching in the dark, and in a child that darkness can be lethal. [8] [10]
From a poisoned child to the right antidote
- 1
1 · Resuscitate
Secure the airway, support breathing with bag-valve-mask if the rate or effort is inadequate, and restore circulation with fluid boluses. An antidote never precedes the ABCDE assessment.
- 2
2 · Identify the toxin
Take a focused history — what, how much, when, by what route — and examine for a toxidrome. Call the regional poison information centre early for any unknown or mixed ingestion.
- 3
3 · Match the mechanism
Decide whether the antidote must occupy a receptor, bind the toxin, restore a substrate, or supply antibody. The mechanism dictates the agent and the dose interval.
- 4
4 · Give the weight-based dose
Calculate every antidote dose from the child's weight, give it by the correct route, and titrate where the drug has a narrow margin — naloxone to respiratory rate, N-acetylcysteine to the protocol.
- 5
5 · Monitor and reassess
Watch for both recurrence of toxicity and for antidote adverse effects. Many antidotes are shorter-acting than the toxin they reverse, so renarcotisation and rebound are real risks.
References12ShowHide
- [1]Dart RC, Mullins ME, Matoushek T, et al. Management of Acetaminophen Poisoning in the US and Canada: A Consensus Statement JAMA Network Open, 2023.PMID 37552484
- [2]Chiew AL, Gluud C, Brok J, et al. Interventions for paracetamol (acetaminophen) overdose Cochrane Database of Systematic Reviews, 2018.PMID 29473717
- [3]Boyer EW Management of opioid analgesic overdose New England Journal of Medicine, 2012.PMID 22784117
- [4]Malmros Olsson E, Lönnqvist PA, Stiller CO, et al. Rapid systemic uptake of naloxone after intranasal administration in children Paediatric Anaesthesia, 2021.PMID 33687794
- [5]Hadland SE, Agarwal R, Raman SR, et al. Opioid prescribing for acute pain management in children and adolescents in outpatient settings: clinical practice guideline Pediatrics, 2024.PMID 39344439
- [6]Isbister GK, Jenkins S, Downes MA, et al. Randomised controlled trial and prospective cohort investigating antivenom for red-bellied black snake envenomation Clinical Toxicology, 2024.PMID 38913734
- [7]Sankar J, Nabeel R, Sankar MJ, et al. Factors affecting outcome in children with snake envenomation: a prospective observational study Archives of Disease in Childhood, 2013.PMID 23716133
- [8]Fine JS Iron poisoning Current Problems in Pediatrics, 2000.PMID 10742921
- [9]McGuigan MA Acute iron poisoning Pediatric Annals, 1996.PMID 8775917
- [10]Bradberry S, Vale A Dimercaptosuccinic acid (succimer; DMSA) in inorganic lead poisoning Clinical Toxicology, 2009.PMID 19663612
- [11]Rogan WJ, Dietrich KN, Ware JH, et al. Effect of chelation therapy with succimer on neuropsychological development in children exposed to lead New England Journal of Medicine, 2001.PMID 11346806
- [12]Lasoff DR, Ruha AM, Curry SC, et al. New Fab 2 antivenom for the treatment of crotaline envenomation in children American Journal of Emergency Medicine, 2016.PMID 27567423