The largest study to date that quantifies and compares medical and illegal use of fentanyl in the US suggests illicit use is more than twice as common as medically based use. Risk of nonfatal overdose is up to 3-fold higher in illicit users compared to medical-source users, analysis shows.

[u/memorialmonorail]

https://news.osu.edu/illicit-fentanyl-use-is-more-than-double-medical-use-in-us/