Activated charcoal

How it works

Its very large adsorptive surface area binds many drugs and poisons within the gut lumen, forming a non-absorbable complex that is eliminated in the faeces and thereby reducing systemic absorption of the toxin.

Prescribing in practice

• Because of the risk of aspiration, it should not be given to patients with a reduced or deteriorating level of consciousness unless the airway is protected, and it is contraindicated where the airway cannot be safeguarded.
• It is generally most effective when given soon after ingestion and does not bind certain substances well (such as iron, lithium, alcohols, strong acids and alkalis), so it is not useful in all poisonings.
• Avoid in suspected gastrointestinal obstruction, perforation or ileus, and seek poisons-service advice on indication, timing and whether repeated doses are appropriate.

Monitoring

Monitor conscious level, airway and bowel function, and tailor management to the specific poison with guidance from a poisons information service.

Counselling the patient

• Explain that the charcoal works by soaking up the poison in the stomach and gut so less is absorbed.
• It is most effective when taken promptly after the overdose and turns the stools black, which is harmless.
• Report any vomiting, abdominal pain or difficulty staying awake.

Evidence & guidelines

Activated charcoal is supported by national poisons guidance as a decontamination option in selected early presentations, with use individualised to the toxin and the patient's airway status.