Contents lists available at ScienceDirect Addictive Behaviors journal homepage: www.elsevier.com/locate/addictbeh Sex differences in patterns of prescription opioid non-medical use among 10–18 year olds in the US Vicki Osborne a,d, ⁎ , Catherine W. Striley a , Sara J. Nixon b , Almut G. Winterstein a,c , Linda B. Cottler a a Department of Epidemiology, University of Florida, Gainesville, FL, USA b Department of Psychiatry, University of Florida, Gainesville, FL, USA c Department of Pharmaceutical Outcomes and Policy, University of Florida, Gainesville, FL, USA d Drug Safety Research Unit, Southampton, UK HIGHLIGHTS • The majority of youth endorsing NMU reported using someone else's opioids • Females most often reported using opioids that belonged to a parent or classmate • Males most often reported using opioids that belonged to a classmate • Strategies should prevent youth from sharing opioids with friends from school ARTICLE INFO Keywords: Youth opioids Non-medical use Sex differences ABSTRACT Background: Non-medical use (NMU) of prescription opioids is a public health concern and sex differences in prevalence of NMU have been observed previously. Little is known about how youth are obtaining and using these drugs. While any regular use could be problematic, NMU is particularly concerning. More information is needed on NMU patterns among youth and how these patterns might differ by sex. Methods: The National Monitoring of Adolescent Prescription Stimulants Study (N-MAPSS) recruited youth 10–18 years of age from 10 US metropolitan areas from 2008 to 2011 with a final sample of 11,048 youth. The cross-sectional survey included questions on past 30 day use of prescription opioids (10,965 provided responses), with NMU defined as non-oral use and/or use of someone else's opioids. NMU through use of a patient's own prescription orally for a reason other than prescribed could not be identified, though this is usually contained within the standard definition of NMU. Results: Among the 10,965 youth, past 30 day prevalence of NMU of prescription opioids was 3.1% (n = 345) with 59.7% (n = 206) using someone else's opioids only, 5.2% (n = 18) having non-oral use only and 35.1% (n = 121) having both. In total, seven sources and three routes of administration were assessed. The most common source among males was someone from school (n = 111, 60.0%), with no highly prevalent second source. Among females, there were two prevalent sources of prescription opioids; a parent (n = 59,41.6%) and someone from school (n = 53,37.3%). For non-oral use, snorting prescription opioids was more frequent among males compared to females (n = 85, 31.8% and n = 44, 17.1%; p < .01). Conclusions: Based on these findings, to combat the current opioid crisis, implementation of strategies to prevent youth from sharing opioids, especially with friends from school, should be considered and tested. 1. Introduction Non-medical use (NMU) of prescription opioids is a concern in the United States (US) because prescription opioid use has increased dra- matically in the past 25 years and NMU is associated with many adverse consequences, including increased risk of overdose (Mojtabai, 2017; National Institute on Drug Abuse, 2014; Pezalla, Rosen, Erensen, Haddox, & Mayne, 2017). In 2015, there were 22,000 deaths in the US from overdose of prescription opioids, an increase of nearly 3000 deaths from 2014 (Centers for Disease Control and Prevention, 2017). https://doi.org/10.1016/j.addbeh.2018.10.009 Received 25 April 2018; Received in revised form 10 September 2018; Accepted 7 October 2018 ⁎ Corresponding author at: 2004 Mowry Rd, PO Box 100231, Gainesville, FL 32610, USA. E-mail address: vicki.osborne@dsru.org (V. Osborne). Addictive Behaviors 89 (2019) 163–171 Available online 09 October 2018 0306-4603/ © 2018 Elsevier Ltd. All rights reserved. T