Stevens-Johnson syndrome (SJS) is a hypersensitivity disorder mediated by immune-complex formation. It is a potentially fatal systemic disorder that is a severe type of erythema multiforme. SJS is also known as “erythema multiforme major.”

The frequency of SJS is estimated to be about 1.2:1,000,000 to 6:1,000,000. This disorder has been reported in all racial and ethnic groups and affects both sexes about equally over all age groups.

Stevens-Johnson syndrome is classified into four categories (see box below). Approximately half of all cases of SJS have been linked to ingestion of a medication. To date, more than 100 different medications have been linked to the development of SJS (see box on pp. 321-322). The second most common cause result from infectious agents/vectors (see box on p. 321). As many as 25% of SJS cases are deemed idiopathic, while the smallest number of SJS cases have been associated with some form of carcinoma and/or lymphoma.