30th July 2026

Epidemiology

Both SJS and TEN are relatively rare with an estimated incidence of between 4 to 7 cases per million per year. The conditions have a female predominance, affect all ages and are twice as common in Asian and black populations. Several HLA allotypes, in particular, HLA-B*1502 in Han Chinese, Thai, Malaysian and South Indian patients taking anticonvulsants and Europeans with HLA-B*5701 allotype taking abacavir or HLA-A*3101 taking carbamazepine have been associated with an increased risk of SJS/TEN.