Many surgeons are prescribing more opioids than are needed.
Researchers from the University of Michigan studied data from over 2-thousand patients and found they only took about a quarter of the pills they were prescribed.
The size of the prescription played a bigger factor in their usage, compared with a patient's level of pain.
The more pills a person was given the more they used.
Researchers say the study shows patients need to have a way to dispose of unused pills safely in order to avoid addiction or overdosing.