We aimed to determine clinical effectiveness of pharmacological interventions for self-injurious behaviour in adults with intellectual disability. We searched the following databases: CENTRAL; MEDLINE; EMBASE; PsycINFO; CINAHL; SCI; SSCI; Conference Proceedings Citation Index - Science; Conference Proceedings Citation Index – Social Science and Humanities; ZETOC; World Cat .We also searched ClinicalTrials.gov,ICTRP and the reference lists of included trials. We included randomised controlled trials that examined drug interventions versus placebo for self-injurious behaviour. We found five double-blind, placebo-controlled trials, which included a total of 50 people. Four trials compared the effects of naltrexone versus placebo and one trial clomipramine versus placebo. We did not identify any relevant placebo-controlled trials for other drugs. We presented a narrative summary, as meta-analysis was not appropriate due to differences in study designs, differences between interventions and heterogeneous outcome measures. There was weak evidence in included trials that any active drug was more effective than placebo for people with intellectual disability demonstrating self-injurious behaviour. Due to sparse data, an absence of power and statistical significance, and high risk of bias for four of the included trials, we are unable to reach any definite conclusions about the relative benefits of naltrexone or clomipramine compared to placebo.