Activated Charcoal for Poisoning: How It Works & Why It's Used

Activated charcoal (AC) is a first-line gastrointestinal decontaminant for many acute poisonings. It’s not a universal antidote but adsorbs a wide range of toxins.

Mechanism of Action

• Highly porous carbon with enormous surface area (~1000–3000 m²/g)
• Adsorbs toxins via van der Waals forces, hydrogen bonding, electrostatic interactions
• Prevents GI absorption → reduces systemic toxicity
• Does NOT adsorb: alcohols, strong acids/bases, iron, lithium, petroleum distillates, cyanide

Indications

• Recent ingestion (<1–2 hours, up to 4h for delayed-release)
• Toxins with good adsorption: antidepressants, antipsychotics, beta-blockers, calcium channel blockers, digoxin, theophylline, anticonvulsants, many OTC drugs
• Multiple-dose AC for enterohepatic recirculation drugs (carbamazepine, phenobarbital, theophylline)

Administration

• Dose: 1 g/kg (adults 50–100g) as slurry in water
• Repeat doses (12.5 g/hr) for multiple-dose protocol
• Give via NG tube if airway unprotected (with cuffed ETT)

Contraindications & Risks

• Unprotected airway (aspiration risk → pneumonitis)
• GI perforation/obstruction
• Caustic ingestion (endoscopy needed)
• Sorbitol-containing AC in children (electrolyte shifts)

Side Effects

• Vomiting (20–30%), constipation, black stools
• Rare: bowel obstruction, bezoar formation

AC is adjunctive—never replaces supportive care, antidotes, or enhanced elimination. Always contact poison control (1-800-222-1222).