The legal drug that killed Prince was 50 times stronger than heroin - and overdose deaths are creating an 'unprecedented' epidemic

Fentanyl, the drug that killed Prince, is an opioid painkiller that's 50 times stronger than pure heroin.

Although the deadly drug is legal with a doctor's prescription, it's also being made illegally in underground labs and traded across the US.

A new CDC report, released August 25, found that from 2013-2014:

• Incidents of law enforcement officers finding drugs containing fentanyl jumped 426%.
• Deaths from synthetic opioids like fentanyl rose by 79%.

"In contrast to the 2005-2007 fentanyl overdose outbreak, when deaths were confined to several states, the current epidemic is unprecedented in scope," the report states.

Here's what you need to know about it: