If a person has swallowed a poison, when should you not make them vomit?

Making a person vomit after swallowing poison can sometimes be beneficial, but it is crucial to avoid inducing vomiting in specific situations, particularly when corrosive poisons have been ingested. Corrosive poisons, such as strong acids or alkalis, can cause severe damage to the esophagus and mouth upon entering the body. If vomiting is induced, the harmful substance can re-enter these tissues, causing even more significant injury as it travels back up through the esophagus. Therefore, in cases of corrosive poisoning, medical professionals recommend against making the individual vomit, as the risks far outweigh any potential benefits.

In contrast, other factors such as a person's consciousness or alertness do not inherently dictate the need to avoid inducing vomiting, and the unknown nature of the poison itself can sometimes warrant different actions based on professional medical advice. Hence, the most critical consideration in this context is the nature of the poison, specifically when it is corrosive.