Fentanyl crisis grips Mexico's US border cities | BBC News

The synthetic opioid fentanyl is 50 times stronger than heroin and is responsible for tens of thousands of overdose deaths in the US last year.

Police in the US have told the BBC that the public health crisis is comparable to a modern day crack epidemic.

It’s a problem that is also sweeping Mexico’s border cities, as drug cartels begin to cut the substance into other drugs like cocaine.