Ann Arbor, Michigan - A new University of Michigan study about substance abuse confirms why parents should properly dispose of leftover prescription opioids.

When teens use codeine, hydrocodone, oxycodone and other prescription opioids for nonmedical purposes, they become at risk to develop a substance use disorder by age 35, U-M researchers said.

In contrast, appropriate medical use of opioid-providing pain relief during adolescence does not increase the risk of substance abuse in adulthood, said Sean Esteban McCabe, the study's lead author and a research professor at the U-M Institute for Research on Women and Gender.

Researchers used data from the NIDA-funded national longitudinal Monitoring the Future study at U-M's Institute for Social Research, which tracks alcohol and other drug use among more than 4,000 high school seniors from graduating classes (1976-1996) to adulthood (1993-2013).

Nearly one-fourth of adolescents indicated lifetime medical use of prescription opioids or nonmedical use of prescription opioids at age 18. More than 90 percent of those who reported nonmedical use of opioids at age 18 did not continue misusing them through age 35.

However, about 53 percent of adolescents who reported only nonmedical use of prescription opioids at age 18 reported two or more substance use disorder symptoms at age 35.

Further, more than a quarter of teens who reported medical use of prescription opioids also had a history of nonmedical use of prescription opioids at age 18—which was linked to an increased risk of opioid misuse and substance abuse in adulthood.

The association between medical use of prescription opioids and subsequent nonmedical use of prescription opioids could be driven partially by the fact that more than a third of adolescents who report nonmedical use of prescription opioids used leftover medications from their own previous prescriptions.

"These findings indicate to health professionals and parents that enhanced vigilance is needed when prescribing opioids and monitoring their use among adolescents to reduce subsequent prescription opioid misuse and substance use disorders," said McCabe, who collaborated on the study with colleagues Philip Veliz, research assistant professor at the Institute for Research on Women and Gender, and John Schulenberg, research professor at the Institute for Social Research and Department of Psychology.