RAND Corporation May 10 2025 More Americans use illicit opioids such as fentanyl than previously estimated, highlighting the need for better methods to understand the depths of the opioid crisis, according to a new study. A survey of American adults found that 11% reported illicit opioid use within the past 12 months and 7.5% reported use of illicitly produced fentanyl during the same period, rates that are more than 20 times higher than estimates from a large federal study that annually asks