It is more often seen with drugs with long half-lives compared to even a chemically similar related drug with a short half-life.More than 200 medications have been reported in association with SJS/TEN. Polymorphisms to specific genes have been detected (eg, CYP2C coding for cytochrome P450 in patients reacting to anticonvulsants).There are HLA associations in some races to anticonvulsants and allopurinol.It is 100 times more common in association with human immunodeficiency virus infection ( HIV).

It is slightly more common in females than in males.

It can affect all age groups and all races.

Anyone on medication can develop SJS/TEN unpredictably.

SJS/TEN is a very rare complication of medication use (estimated at 1–2/million each year for SJS, and 0.4–1.2/million each year for TEN). Using current definitions, it is nearly always caused by medications. SJS/TEN is a rare, acute, serious, and potentially fatal skin reaction in which there are sheet-like skin and mucosal loss. Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are now believed to be variants of the same condition, distinct from erythema multiforme. What are Stevens–Johnson syndrome and toxic epidermal necrolysis?

Phase ten