Drug overdose deaths soared to 60,000 people in the US last year, and synthetic fentanyl is largely to blame. Fentanyl is 50 to 100 times stronger than morphine. The Centers for Disease Control reports fentanyl is now a major driver of opioid overdose deaths. Authorities are seeing analogs of fentanyl mixed in with drugs like cocaine and heroin. Those analogs include car-fentanyl, which is 10,000 times stronger than morphine. It's used to tranquilize large animals.