Prescription opioids are closely related to heroin chemically, and their effects can be very similar, especially when misused. Nearly 80 percent of people addicted to heroin started first with prescription opioids. Heroin can be cheaper to get, so about 4% of people who misuse prescription pain medications switch to heroin. This adds up to hundreds of thousands of heroin users, because millions of people are misusing prescription opioids.2
2 Compton WM, Jones, CM, Baldwin GT. Relationship between nonmedical prescription-opioid use and heroin use. England Journal of Medicine, 2016, 374:154-163.