Why is fentanyl so deadly? What was it originally for?

In the early 1960s the synthetic opioid was manufactured and approved by the FDA a few years later, for a specific purpose: to treat pain.

Fentanyl is so potent doctors don't know how to fight it

Nearly 70,000 People Died of Overdoses Involving Fentanyl in 1

Why the Pain Drug That Killed Prince Can Be Especially Dangerous

A grain of sand: Why fentanyl is so deadly

Rainbow fentanyl found in Placer County, district attorney says

DEA Washington Division Announces the Seizure of Over 8 Million of

What to know about fentanyl, the leading cause of U.S. overdose

Q&A: What you need to know about fentanyl

HSC's fentanyl awareness campaign