Heroin is readily available in most large metropolitan areas and, to varying degrees, in suburban and rural markets throughout the country. Although overall abuse levels for heroin are lower than levels for other drugs, including cocaine and marijuana, the consequences of heroin abuse are far reaching in terms of heroin-related deaths, treatment admissions, and emergency department mentions. Since late 2005, the suspected number of heroin-related overdose deaths involving fentanyl has been indicative of the risks attendant to heroin abuse, including inconsistent purity levels and diluents and adulterants that can cause serious and often fatal consequences. Demand for heroin in the United States is largely driven by a well-established population of roughly 800,000 hardcore heroin addicts. Overall, demand is relatively stable, with gradual increases noted in some user populations. The physical need for opiate abusers to obtain opiate-type drugs to stave off withdrawal has led some addicts to switch from prescription drugs to heroin. Anecdotal law enforcement reporting indicates that abusers of pharmaceutical opioids, primarily OxyContin and methadone, but other drugs as well, have switched and continue to switch to heroin, particularly when heroin is more available and cheaper.