Stevens

A painful, rapidly progressive eruption after a medication is not an ordinary drug rash until Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been excluded. Patients may develop fever or malaise followed by skin tenderness, dusky atypical targetoid macules, flaccid blisters, and epidermal detachment. Erosions of the eyes, mouth, airway, genital tract, or urinary tract can threaten function even when the detached skin area is small. Classify severity by detached or detachable epidermis: SJS involves less than 10% of total body surface area (TBSA), SJS/TEN overlap involves 10–30%, and TEN involves more than 30%. The immediate danger is loss of the skin barrier with fluid loss, pain, infection risk, and mucosal organ injury. Stop non-essential suspect medications, assess airway and circulation, and arrange emergency hospital-level care while diagnostic workup proceeds. In Canada, the NP works within provincial or territorial authorization and local transfer protocols; suspected SJS/TEN should not remain an outpatient prescribing problem.