Managing the poisoned patient
The general approach to a poisoning: support breathing and circulation first, then decontaminate, speed removal and give an antidote when one exists.
Most poisoned patients recover with good supportive care, whatever the toxin. The approach has the same order every time: stabilise the airway, breathing and circulation; check glucose; identify the toxin from the history, the examination and tests; limit absorption; increase elimination when it helps; and give a specific antidote when there is one.
Stabilise first
Clear and protect the airway, assess breathing with oximetry and, when in doubt, blood gases, and support the circulation. Patients in respiratory failure are intubated and ventilated. A bedside glucose check is done in anyone with altered consciousness, because hypoglycaemia can look exactly like intoxication. An opioid overdose (pinpoint pupils, unconsciousness, slow breathing) is reversed with naloxone, but ventilation remains the life-saving step.
Find the toxin
Ask what, how much, when and by which route; look for empty packages and ask relatives. Examine pupils, skin, temperature, bowel sounds and mental state, and match the pattern to a toxidrome. Useful tests include electrolytes with the anion gap, the osmolar gap (toxic alcohols), an ECG (QRS and QT widening), and specific levels such as paracetamol or salicylate.
Decontamination
- Skin and eyes: remove contaminated clothing and wash with water (and soap for skin).
- Activated charcoal: the usual gut decontamination for most ingestions, best soon after the ingestion; it binds alcohols and cyanide poorly.
- Gastric lavage: only in unusual cases, with the airway awake or protected.
- Whole-bowel irrigation: for iron tablets, sustained-release or enteric-coated drugs and drug packets.
- Induced vomiting: no longer recommended.
Enhanced elimination
Forced diuresis is not recommended. Alkalinising the urine traps salicylate in its ionised form and speeds its excretion. Haemodialysis is especially useful for toxins with a small volume of distribution, low protein binding and low molecular weight (salicylate, lithium, methanol, ethylene glycol) and also corrects acidosis. Repeated doses of activated charcoal can increase the clearance of a few drugs, such as carbamazepine and phenobarbital.
Antidotes
Antidotes exist for a minority of poisons, and they work best with good supportive care. Examples: acetylcysteine for paracetamol (most effective when started early), fomepizole for methanol and ethylene glycol, atropine and pralidoxime for organophosphates, naloxone for opioids, physostigmine for severe anticholinergic delirium, deferoxamine for iron, chelators for lead. Flumazenil reverses benzodiazepines but can provoke seizures in long-term users or after a tricyclic overdose, so it is not routine in mixed overdoses.
Help in Colombia
The Ministry of Health and PAHO publish the Guía para el Manejo de Emergencias Toxicológicas, and the Línea Nacional de Toxicología gives free advice by telephone at any hour to health teams and the public, including how to report the case to SIVIGILA.
Test yourself
Think of the answer, then tap the question to see it.
Why is glucose checked in every patient with altered consciousness?
Hypoglycaemia can mimic intoxication and there is no fast clinical way to tell them apart; it is easy to detect and treat.
Which three substances does activated charcoal not bind well?
Iron, lithium and potassium (it also binds alcohols and cyanide poorly and does not help with corrosives).
How does urine alkalinisation help in salicylate poisoning?
It keeps salicylate in its ionised form in the urine, so less is reabsorbed and more is excreted.
Why is flumazenil not given routinely in an unknown overdose?
It can trigger seizures, especially in long-term benzodiazepine users or after a tricyclic antidepressant overdose.
Example drugs
- Activated charcoal
- Naloxone
- Flumazenil
- Acetylcysteine
- Fomepizole
- Atropine
- Pralidoxime
- Physostigmine
- Deferoxamine
Connections
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - ACETYLCYSTEINE injection, solution (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - FLUMAZENIL injection, solution (DailyMed (U.S. National Library of Medicine), 2026); Línea nacional de toxicología (Ministerio de Salud y Protección Social, Colombia, 2026); Guía para el Manejo de Emergencias Toxicológicas (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017).
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Representative model, for educational purposes only.