What is the use of activated charcoal in cases of poisoning or drug overdose, particularly in patients with a history of gastrointestinal issues or other underlying medical conditions?

Activated Charcoal in Poisoning and Overdose

Primary Indication and Mechanism

Activated charcoal is used for gastrointestinal decontamination in poisoning by adsorbing toxins in the gut, thereby reducing systemic absorption of ingested substances. 1

• It works through adsorption rather than as a true antidote, binding toxins to prevent their absorption from the gastrointestinal tract 2
• The standard adult dose is 50 grams orally or via nasogastric tube, with pediatric dosing at 1-2 g/kg body weight 1, 3, 4

Critical Timing Considerations

Activated charcoal should be administered within 1 hour of toxin ingestion for maximum benefit, though it may be considered up to 4 hours post-ingestion for certain substances. 1, 5, 6

• For acetaminophen overdose, administer just before N-acetylcisteína when identified within 4 hours 1
• For Direct Oral Anticoagulants (DOACs), give within 2-3 hours of last dose 1
• For tricyclic antidepressants like nortriptyline, may be effective even up to 4 hours post-ingestion 1
• For timed-release preparations, administration can extend up to 6 hours post-ingestion 6

Absolute Contraindications

Do not administer activated charcoal if the patient has impaired consciousness or absent airway protective reflexes without a secured airway. 1, 4

• Contraindicated in caustic substance ingestions (strong acids or bases) as it may cause additional harm 1, 4
• Do not use for substances not adsorbed by charcoal: iron, lithium, alcohols, ethylene glycol, alkalis, fluoride, mineral acids, potassium, petroleum distillates (kerosene, gasoline, paint thinner) 1, 4
• Avoid in patients with gastrointestinal perforation, obstruction, or recent gastrointestinal surgery 1

Special Population Considerations

For children under 1 year old, use only non-sorbitol-containing formulations, as sorbitol has caused fatal hypernatremic dehydration. 1, 3

• Pediatric dosing: Ages 0-10 years: 10-25 g; Ages 10-12 years: 25-50 g; Over 12 years: 25-100 g 4
• Do not administer to children who are not fully conscious 4

Clinical Decision Algorithm

Before administering activated charcoal, verify:

1. Airway status: Patient must be fully conscious with intact protective reflexes OR have a secured airway 1, 4
2. Timing: Ideally within 1 hour, up to 4 hours for select substances 1, 5, 6
3. Substance identification: Confirm the toxin is charcoal-adsorbable 1, 4
4. Caustic exposure: Rule out acids, bases, or petroleum products 1, 4
5. Patient age: If under 1 year, ensure sorbitol-free formulation 1, 3

Always contact poison control centers for guidance when uncertainty exists. 1, 3

Evidence Quality and Current Practice

The American Heart Association and American Red Cross state there is insufficient evidence to recommend for or against routine activated charcoal use in first aid settings 1, 3. However, this reflects the limitation of lay rescuer administration, not hospital-based use.

• Activated charcoal should not be administered routinely but may be considered when appropriate criteria are met 1
• In Canadian emergency departments, only 12.8% of poisoned patients received activated charcoal, with most progressing well clinically 7
• Human volunteer studies demonstrate effectiveness with decreasing benefit over time, though randomized controlled trials have not consistently shown clinical outcome improvement 8, 9

Multiple-Dose Activated Charcoal

Multiple-dose activated charcoal may be beneficial for substances with enterohepatic circulation but should only be administered under medical supervision. 1, 3

• Indicated for intoxications with drugs that persist longer in the stomach, timed-release preparations, or drugs with marked enterohepatic/entero-enteric circulation 6
• The routine combination with laxatives is not recommended 6

Common Pitfalls to Avoid

• Do not wait for vomiting to occur before administration unless specifically directed by a healthcare professional 4
• Do not use in unconscious patients or those having convulsions 4
• Avoid aspiration risk: The most common side effect is vomiting (20.8%), with aspiration pneumonia occurring rarely (0.01%) 7
• Do not administer by lay rescuers without poison control center direction 1, 3

Priority of Care

Always prioritize airway protection and hemodynamic stabilization before considering gastrointestinal decontamination. 1, 3, 10