ABSTRACT: BACKGROUND:Prescription opioid misuse has become a leading cause of unintentional injury and death among adolescents and young adults in the United States. However, there is limited information on how adolescents and young adults obtain prescription opioids. There are also inadequate recent data on the prevalence of additional drug abuse among those misusing prescription opioids. In this study, we evaluated past-year prevalence of prescription opioid use and misuse, sources of prescription opioids, and additional substance use among adolescents and young adults. METHODS AND FINDINGS:This was a retrospective analysis of the National Survey on Drug Use and Health (NSDUH) for the years 2015 and 2016. Prevalence of opioid use, misuse, use disorder, and additional substance use were calculated with 95% confidence intervals (CIs), stratified by age group and other demographic variables. Sources of prescription opioids were determined for respondents reporting opioid misuse. We calculated past-year prevalence of opioid use and misuse with or without use disorder, sources of prescription opioids, and prevalence of additional substance use. We included 27,857 adolescents (12-17 years of age) and 28,213 young adults (18-25 years of age) in our analyses, corresponding to 119.3 million individuals in the extrapolated national population. There were 15,143 respondents (27.5% [95% CI 27.0-28.0], corresponding to 32.8 million individuals) who used prescription opioids in the previous year, including 21.0% (95% CI 20.4-21.6) of adolescents and 32.2% (95% CI 31.4-33.0) of young adults. Significantly more females than males reported using any prescription opioid (30.3% versus 24.8%, P < 0.001), and non-Hispanic whites and blacks were more likely to have had any opioid use compared to Hispanics (28.9%, 28.1%, and 25.8%, respectively; P < 0.001). Opioid misuse was reported by 1,050 adolescents (3.8%; 95% CI 3.5-4.0) and 2,207 young adults (7.8%; 95% CI 7.3-8.2; P < 0.001). Male respondents using opioids were more likely to have opioid misuse without use disorder compared with females (23.2% versus 15.8%, respectively; P < 0.001), with similar prevalence by race/ethnicity. Among those misusing opioids, 55.7% obtained them from friends or relatives, 25.4% from the healthcare system, and 18.9% through other means. Obtaining opioids free from friends or relatives was the most common source for both adolescents (33.5%) and young adults (41.4%). Those with opioid misuse reported high prevalence of prior cocaine (35.5%), hallucinogen (49.4%), heroin (8.7%), and inhalant (30.4%) use. In addition, at least half had used tobacco (55.5%), alcohol (66.9%), or cannabis (49.9%) in the past month. Potential limitations of the study are that we cannot exclude selection bias in the study design or socially desirable reporting among participants, and that longitudinal data are not available for long-term follow-up of individuals. CONCLUSIONS:Results from this study suggest that the prevalence of prescription opioid use among adolescents and young adults in the US is high despite known risks for future opioid and other drug use disorders. Reported prescription opioid misuse is common among adolescents and young adults and often associated with additional substance abuse, underscoring the importance of drug and alcohol screening programs in this population. Prevention and treatment efforts should take into account that greater than half of youths misusing prescription opioids obtain these medications through friends and relatives.