Fentanyl is among the strongest pain medications. It is up to 50 to 100 times more potent than morphine and many magnitudes stronger than heroin. A synthetic opioid, fentanyl is prescribed in limited circumstances, such as the treatment of severe post-surgery pain.   Increasingly, fentanyl is abused for recreational purposes. Additionally, many drug traffickers now cut batches of heroin with fentanyl, often with deadly consequences.