DRESS is one of the most severe drug reactions. The aim of this retrospective study was to summarize the clinical presentation, genetic predisposition and prognostic factors of DRESS. A total of 52 patients with DRESS, who were inpatients at a medical referral centre in Shanghai, China, from January 2011 to December 2016, were analysed retrospectively. All the patients had skin eruption, 83% had liver involvement, and ≤10% had other organ involvement. Mean cost of hospitalization was US$5,511±3,050. The 3 most common causative agents were allopurinol (18/52; 35%), salazosulphapyridine (11/52; 21%) and carbamazepine (5/52; 10%). HLA-B*5801 and HLA-B*1302 were associated with allopurinol-induced DRESS. HLA-B*1301 was related to salazosulphapyridine-induced DRESS. The mortality rate was 6% (3/52). Epstein-Barr virus DNA was found in 10 patients (19%) and indicated a poor prognosis. Human herpes virus 6 DNA was detected in 17 patients (33%) and was associated with autoimmune sequelae. Due to its high medical cost and sometimes poor prognosis, prevention of DRESS should be a high priority.