Placing time limits on opioid prescriptions may reduce the risk of misuse, a new study suggests.

A research team from the University of Michigan found 1% of opioid prescriptions from U.S. dentists and surgeons were filled more than 30 days after they were issued in 2019, HealthDay reports. The prescriptions were written for short-term pain, which should have subsided in less than 30 days, the researchers said.

They calculated that 1% of all surgical and opioid prescriptions in the U.S. would add up to more than 260,000 opioid prescriptions annually that are filled more than a month after being written.

“Our findings suggest that some patients use opioids from surgeons and dentists for a reason or during a time frame other than intended by the prescriber,” lead study author Dr. Kao-Ping Chua said in a news release. “These are both forms of prescription opioid misuse, which in turn is a strong risk factor for opioid overdose.”

In 2019, 18 states allowed prescriptions for opioids and other controlled substances to be filled up to 6 months after writing. An additional 8 states permitted these medications to be dispensed up to a year after the prescription was written.

Chua suggested that stricter state laws could help prevent or reduce prescription opioid misuse associated with delaying filling of prescriptions.