A study conducted by the Mayo Clinic finds that one in four people prescribed an opioid medication ended up using the medication longer than intended.

The study looked at a random sample of 293 patients who were prescribed a painkiller in 2009. The popular prescriptions included Oxycodone, morphine and codeine. The study found that 21 percent of people used the prescriptions for three to four months, slightly longer than anticipated. Also, six percent of people used the opioids for more than four months, much longer than anticipated and probably longer than needed. Those who extended their prescriptions also used tobacco products or had a history of substance use disorders. The researchers point out that this is a strong connection because of how similar the brain reacts to tobacco and opioids.

Researchers on the study suggest physicians closely monitor their patients who are on an active opioid medication in order to prevent addiction. It is also important for the physician to inform the patient on the addictive risks of the medication.