A patient taking prolonged antibiotics develops a severe rash with mucosal involvement. What syndrome is this?

Stevens-Johnson Syndrome (SJS) is a severe, potentially life-threatening mucocutaneous reaction often triggered by drugs (sulfonamides, penicillins, anticonvulsants). It presents with targetoid skin lesions, mucosal ulceration (oral, ocular, genital), and systemic symptoms. SJS is <10% BSA involved; >30% = Toxic Epidermal Necrolysis (TEN). Requires hospitalization.