Final answer:
Prednisone is the contraindicated medication for a client with a history of Stevens-Johnson syndrome when taking sulfamethoxazole-trimethoprim.
Step-by-step explanation:
Stevens-Johnson syndrome is a severe hypersensitivity reaction that can occur when taking sulfamethoxazole-trimethoprim. The nurse should identify medications that may cause similar reactions, or exacerbate the symptoms of Stevens-Johnson syndrome, as contraindicated for this client. Among the medications listed, Prednisone is a systemic corticosteroid that can suppress the immune system and may increase the risk of adverse reactions in individuals with Stevens-Johnson syndrome.