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Approach to the poisoned patient and toxidromes
In a poisoned patient, stabilise first (ABC, glucose, ECG), recognise a toxidrome from vital signs, pupils, skin and bowel sounds, exclude a co-ingestion of paracetamol and salicylates, and only then decide on decontamination, a specific antidote or enhanced elimination.
Why it matters in the exam
Toxicology questions rest on recognising a toxidrome from a short description: small pupils and slow breathing (opioids), large pupils with dry hot skin (anticholinergic), large pupils with sweating (sympathomimetic), small pupils with salivation and secretions (cholinergic). The correct answer almost always starts with stabilisation and glucose, not with a broad toxicology screen.
The rules of decontamination are also tested: activated charcoal 1 g/kg (up to 50 g) only when the airway is protected and usually within one hour of ingestion, and not for iron, lithium, alcohols, acids and alkalis or hydrocarbons. Whole bowel irrigation suits iron, lithium, sustained-release preparations and drug packers. Gastric lavage is hardly ever used.
Further questions deal with the supporting tests: paracetamol and salicylate levels in every intentional overdose, even when the patient denies it; an ECG for a wide QRS or long QT; the anion gap and osmolar gap in unexplained acidosis; and a pregnancy test in a woman of child-bearing age. Finally, enhanced elimination is asked — urine alkalinisation for salicylates and dialysis for small, water-soluble toxins with a small volume of distribution — together with early contact with the national poison information centre.
Key points
- Stabilisation, glucose and ECG before anything else.
- A toxidrome is recognised by pupils, skin, temperature and bowel.
- Paracetamol and salicylates are checked in every intentional overdose.
- Activated charcoal 1 g/kg only with a protected airway and a binding substance.
- Dialysis for small soluble toxins: salicylates, lithium, toxic alcohols, metformin.
Summary table
| Toxidrome | Pupils | Main signs | Examples |
|---|---|---|---|
| Opioid | Small | Reduced consciousness, slow shallow breathing | Heroin, morphine, fentanyl |
| Sympathomimetic | Large | Tachycardia, hypertension, fever, sweating, agitation | Cocaine, amphetamines |
| Anticholinergic | Large | Dry flushed skin, fever, delirium, urinary retention, silent bowel | Antihistamines, TCAs, atropine |
| Cholinergic | Small | Salivation, lacrimation, bronchial secretions, diarrhoea, bradycardia, seizures | Organophosphates, carbamates |
| Sedative-hypnotic | Usually normal | Drowsiness, slurred speech, mild respiratory depression | Benzodiazepines, alcohol |
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Sources
- Goldfrank's Toxicologic Emergencies, 11th edition (2019) — Initial evaluation of the patient: vital signs and toxic syndromes
- AACT/EAPCCT Position papers on gastrointestinal decontamination, 2004–2015 updates — Single-dose activated charcoal; whole bowel irrigation
- EXTRIP workgroup recommendations on extracorporeal treatment in poisoning, 2015–2023 — General principles
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.
See also: in children: Poisoning in children