Which adverse drug reaction indicates that a patient should not be rechallenged with that medication?

The occurrence of Stevens-Johnson syndrome, particularly from a medication such as sulfamethoxazole-trimethoprim, signifies a severe and potentially life-threatening adverse drug reaction that is characterized by extensive skin detachment and mucosal involvement. This condition indicates a hypersensitivity reaction that can lead to significant complications, including infection, fluid loss, and long-term morbidity. Given the severity of this syndrome, rechallenging a patient with the same medication after they have experienced such an adverse effect poses an unacceptable risk of recurrence and could lead to further serious health consequences.

In contrast, the other options involve adverse reactions that, while they may be uncomfortable or warrant monitoring, typically do not indicate an absolute contraindication to rechallenge. For instance, an itching rash from penicillin might suggest an allergy but often does not lead to severity comparable to that of Stevens-Johnson syndrome. Gastrointestinal upset from clarithromycin is a common and often manageable side effect, and Clostridium difficile superinfection following moxifloxacin indicates a complication that may not necessarily indicate an allergy or severe hypersensitivity reaction, allowing for a different course of action or treatment choice.

Thus, the recognition of Stevens-Johnson syndrome as a decisive signal against rechallenging with a