Pharmaceutical fentanyl was developed for pain management treatment of cancer patients, applied in a patch on the skin. It is a synthetic opioid 85-100 times stronger than morphine because of its powerful opioid properties, which is why it also gets diverted for abuse.
However, most recent cases of fentanyl-related harm, overdose, and death in the U.S. are linked to illegally made fentanyl. It is sold through illegal drug markets for its heroin-like effect. It is often mixed with heroin and/or cocaine as a combination product—with or without the user’s knowledge—to increase its euphoric effects.