The U.S. Drug Enforcement Agency (DEA) has issued a nationwide alert about the dangers of fentanyl and related compounds (fentanyl analogues). Fentanyl, an opioid that is 50-100 times more powerful than morphine, is both abused on its own and commonly added to heroin to increase its potency. Fentanyl and fentanyl-laced heroin have been a concern for over a decade and have caused numerous overdose deaths among injection drug users in several U.S. cities.
Heroin is not the only drug that can be laced with fentanyl, however. Officials in Vancouver, British Columbia, Canada, recently issued public warnings about a wide range of fentanyl-laced drugs causing overdose deaths among users. They warn that fentanyl is now being concealed in non-injection drugs, including oxycodone and various "party drugs" in powder or pill form, as well as in marijuana (although no deaths have been confirmed from fentanyl-laced marijuana). Because of this new threat, British Columbia officials are urging all recreational drug users to "know their source."
2019 Update: There have been no subsequent reports of marijuana laced with fentanyl since this was first reported by a variety of police agencies in 2015. Initial reports were difficult to verify; NIDA continues to monitor drug use reports through our regional National Drug Early Warning System and other national, state and local channels.