Although rare, drug testing in schools continues to be practised in some European countries. In many cases, drug testing is intended to act as a deterrent to substance use. Nevertheless, studies conducted in the United States show that the drug testing of students can have iatrogenic effects, sometimes being associated with an increase in illicit drug use or an increase in the risks associated with substance use.

To evaluate the effectiveness of random testing in schools, we conducted a systematic review of seven studies that met certain inclusion criteria. These studies were all conducted in the United States among college students between 13 and 19 years of age and in one case among athletes. Although different with regard to study design and the type of testing offered, all of the studies show that testing has little or no effect on drug use. In addition, the invasiveness of the testing procedure and limitations to the information derived from drug testing affect its utility as a prevention approach. In light of this, experts have called for further evidence-based studies to help guide best practice for drug prevention interventions with adolescents.