The researchers studied over 1,000 adults prescribed painkillers like OxyContin or Vicodin shows how some Americans gain illicit access to addictive pain medications.
According to researchers, these patterns are contributing to the epidemic of prescription painkiller abuse and overdose deaths across the US.
More than one in five patients admitted "they have shared an opioid medication with another person, primarily to help that other person manage pain," said study lead author Alene Kennedy-Hendricks, an assistant scientist in the department of health policy and management at the Johns Hopkins Bloomberg School of Public Health, in Baltimore.
Moreover, more than 60 percent of those with leftover opioids said they hung on to their drugs for "future use."
The US Centers for Disease Control and Prevention has already issued warning for doctors directing them about the dangers of overprescribing painkillers because of the risk of addiction.
According to CDC, reliance on painkillers also raises the odds for heroin use, a cheaper drug with similar opioid effects. The deaths from prescription opioids more than tripled in the United States between 1999 and 2014, CDC added.
For the study, 1,055 adults were surveyed by researchers. These adults had been prescribed opioids in the previous year. Nearly 47 percent were taking opioids at the time of the survey. The researchers asked them about their own opioid use, their opioid storage habits, and whether they gave their medication to others.