Activated charcoal contraindication includes:

• A. Altered mental status and ingestion of acids or alkalis
• B. Dehydration
• C. Allergic reaction to charcoal
• D. Ingestion of large volumes of water

Answer: (A)

Activated charcoal works by adsorbing many ingested toxins in the GI tract to limit absorption, but it isn’t used in every poisoning. It is contraindicated when the patient cannot protect their airway (altered mental status or decreased level of consciousness) because charcoal poses a serious aspiration risk. It is also not effective for caustic substances like acids or alkalis, and giving it in those cases can delay definitive care or worsen mucosal injury if aspiration occurs. Therefore the combination of altered mental status and ingestion of caustic substances (acids or alkalis) correctly identifies when activated charcoal should not be used. Dehydration, an allergic reaction to charcoal, or ingestion of large volumes of water do not constitute standard contraindications in the same way.