No study has investigated the ongoing risk of substance use disorders involving illicit drugs (ISUD) after first eating disorder (ED) and whether the pattern of risk differs according to types of ED and ISUD. Therefore, we aimed to longitudinally assess the risk of a subsequent diagnosis of any ISUD (pooled category) and specific ISUD after a first-time diagnosis of anorexia nervosa (AN), bulimia nervosa (BN), or unspecified ED (USED).