"Cannabis is the most frequently reported drug used in prison with a rate between 27% and 32%. Heroin as most frequently used illicit drug in prison after cannabis is a recurrent observation over the years with a rate from 12% up to 13% . A similar rate is observed for the use of benzodiazepines without prescription and is classified as the third product most frequently used in prison over the years 2006-2010.
"Since heroin use seems widespread in prison, respondents were asked, for the first time in the latest survey of 2010, about their mode of administration of heroin during detention. Most drug users in prison declare to inhale the heroin vapour (14%) in contrast to 2% of the prison population stating to inject it. In the case of initiation in the use of new substances during imprisonment, heroin is firstly reported in prison population (6%).
"To gain more insight into the profile of the drug users, prisoners declaring to use drugs during their detention were, also for the first time in 2010, questioned about their frequency of use in prison. It seems that an important part can be categorised as regular users. 11.8% of the prison population declares to use drugs from multiple times a month to weekly and daily use. When the definition of regular use is defined in a more broadly sense, even more than 20% can be defined as frequent users: from once a month to multiple times a month, weekly and daily use."


Deprez, Nathalie, et al., "2011 National Report (2010 data) to the EMCDDA by the Reitox National Focal Point" (Brussels, Belgium: OD Public Health and Surveillance, Scientific Institute of Public Health, October 2011), WIV-ISP/EPI REPORTS N° 002, p. 186.