The growing non-medical use of prescription drugs is a global health concern. Such usage can be defined as the taking of prescription drugs, whether obtained by prescription or otherwise, other than in the manner or for the reasons or time period prescribed, or by a person for whom the drug was not prescribed. The real scale of the problem is unknown, due partly to lack of data on the non-medical use of prescription drugs, and partly to the existence of many gaps in the monitoring of their legal use for medical purposes as prescribed by health-care professionals (which creates opportunities for the diversión of these drugs to people to whom they were not prescribed). Most studies on and monitoring instruments for substancie abuse pertain to the use of illegal drugs, or alcohol and tobacco. However, the non-medical use of prescription drugs is a unique category of substance use in number of ways and requires attention at different levels.