Abstract Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are severe cutaneous adverse drug reactions (ADR). In this study established that the risk of SJS/TEN appearance is increased according to the number of potential cutaneous ADR that are the symptoms of these syndromes (χ2=23.95; odds ratio 1.56 [confidence interval 95%, 1.29-1.88]; p<0,001). All drugs associated with the risk of SJS/TEN appearance were combined into 7 groups by the «GDD» – grade of dermatological danger. Thus, the risk of SJS/TEN appearance is considerably lower if drug with GDD «1» has been administrated compared to drug with GDD «7».