"Multiple studies that have examined why some persons who abuse prescription opioids initiate heroin use indicate that the cost and availability of heroin were primary factors in this process. These reasons were generally consistent across time periods from the late 1990s through 2013.34-41 Some interviewees made reference to doctors generally being less willing to prescribe opioids as well as to increased attention to the issue by law enforcement, which may have affected the available supply of opioids locally.38,40"
Wilson M. Compton, M.D., M.P.E., Christopher M. Jones, Pharm.D., M.P.H., and Grant T. Baldwin, Ph.D., M.P.H. Relationship between Nonmedical Prescription-Opioid Use and Heroin Use. N Engl J Med 2016; 374:154-163. January 14, 2016. DOI: 10.1056/NEJMra1508490.