SJS

Stevens-Johnson syndrome (SJS) is a rare, life-threatening hypersensitivity reaction that involves the skin and mucous membranes. It is characterized by widespread epidermal necrosis and detachment, usually occurring after exposure to a medication or, less commonly, an infection. SJS and toxic epidermal necrolysis (TEN) lie on a spectrum; SJS involves less than 10% of body surface area (BSA) affected, TEN involves more than 30%, with 10–30% designated as SJS/TEN overlap.

Most cases are triggered by drugs such as anticonvulsants (lamotrigine, carbamazepine, phenytoin), allopurinol, sulfonamide antibiotics, penicillins, nonsteroidal anti-inflammatory drugs, and others. Infections, particularly Mycoplasma pneumoniae in children, can also trigger SJS. Genetic factors, including certain HLA alleles, increase risk in some populations and influence drug choice in specific regions.

Prodromal symptoms include fever, malaise, and upper-respiratory symptoms, followed by rapid onset of painful mucosal erosions (in the mouth, eyes, genitalia) and a variegated, evolving rash that may develop vesicles and bullae with epidermal detachment. A positive Nikolsky sign can be observed. Complications include dehydration, secondary infection, electrolyte disturbances, and ocular, respiratory, and genital sequelae.

Diagnosis is clinical and supported by skin biopsy showing full-thickness epidermal necrosis. Immediate management requires stopping the offending drug and providing intensive supportive care—fluid and electrolyte management, wound care, pain control, nutrition, and prevention of infections—often in an intensive care or burn unit. Ophthalmology, dermatology, and infectious disease specialists are typically involved. The effectiveness of systemic steroids, intravenous immunoglobulin, and other immunomodulatory therapies remains debated and is individualized.

Mortality ranges around 5–15%, higher with advanced age, greater body surface involvement, and comorbidities. Most survivors recover over weeks to months, though long-term sequelae—especially ocular dryness, scarring, and vision impairment—may persist.

Incidence is very low, estimated at a few per million per year. Avoidance of known culprit drugs and, where appropriate, pharmacogenomic screening in high-risk populations are key preventive strategies.