Fentanyl has been around for some years now, but its definitely been getting more popular as of late.
Its an opioid pain killer. Shit is no joke and way stronger than any other opiate on the market like Oxycotin, Oxycodone, Hydromorphone, Dilaudid, etc. I think it was primarily created to help cancer patients get through chemo, but they said the same shit about Oxycotin.
Because it is available through prescription, a lot of drug dealers have been using it to cut heroin, but they dont do a very good job all the time and overdo it, thus causing overdoses. Fentanyl is so powerful that typical doses are .25 or .50 of a milligram.
This could be considered a lethal dose a fentanyl to people who have no tolerance: