In what circumstance is activated charcoal contraindicated?

Activated charcoal is contraindicated in the case of a patient who has ingested corrosive substances, such as drain cleaner. The primary reason for this contraindication is that activated charcoal works by adsorbing toxins in the gastrointestinal tract, but it does not neutralize corrosive materials. If a toxic substance has caused chemical burns to the tissues of the esophagus or stomach, administering activated charcoal could exacerbate the injury, and there is a risk that the charcoal itself could become lodged, further damaging the mucosa.

In the case of the patient who is awake and has swallowed drain cleaner, prioritizing the patient's safety and the minimization of further harm is crucial, necessitating a different intervention rather than the use of activated charcoal. This contrasts with situations where activated charcoal may be indicated, such as ingestion of certain medications or non-corrosive substances, where its benefits in absorption outweigh potential risks.