Activated charcoal is contraindicated in which scenario?

• A. Ingestion of a caustic substance
• B. Ingestion of a non-toxic substance
• C. The patient is fully conscious and able to swallow
• D. The patient has a mild upset stomach

Answer: (A)

Activated charcoal is used to bind many ingested toxins in the GI tract, reducing absorption, but it is contraindicated with caustic substances. Caustics can cause severe tissue injury to the mouth, esophagus, and stomach, and charcoal won’t prevent that damage. In fact, if vomiting occurs or if there’s any aspiration risk, charcoal can make lung injury worse. So ingesting a caustic substance is a scenario where charcoal should not be used.

Ingesting a non-toxic substance offers no benefit from charcoal, since there’s nothing harmful to adsorb. If the patient is fully conscious and able to swallow, charcoal can be used when a toxin is suspected and the airway is protected, and a mild upset stomach by itself isn’t a contraindication. The key point is that caustic substances make charcoal unsafe to administer.