Importance: Despite their widespread adoption across the US, policies imposing one-size-fits-all limits on the duration of prescriptions for opioids have shown modest and mixed implications for prescribing.

Question: Do tailored limits on the duration of opioid prescriptions reduce the length of prescriptions for opioid-naive patients?

Findings: This cross-sectional study of 44 703 Medicaid enrollees who received an opioid prescription from 2017 to 2019 before or after implementation of a policy that limited the duration of opioid prescriptions found that implementation was associated with relative reductions of 56.8% for adults in outpatient practices, 37.5% for adults in emergency departments, and 26.5% for pediatric patients in any setting in the proportion of opioid prescriptions exceeding the duration limits.

Meaning: The findings of this cross-sectional study suggest that policies tailored to specific clinical settings may be associated with reduced lengths of opioid prescriptions.