There is a correlation between imprisonment and problematic drug use. A series of studies has shown that drug use in prison is now commonplace and that many inmates come into custody with severe drug use problems. At least half of the European Union’s 356,000 prison population has a history of drug use.

The harmful effects of drug use and especially high-risk behaviors, which occur in prisons, are well documented. Research into drug use in prisons has found that imprisonment impacts on an individual’s pattern of drug use. Drug use in prison is usually carried out in a hurried secret fashion with little regard for safety and many drug users inject in prison, some for the first time.