Fentanyl, also spelled fentanil, is an opioid which is used as a pain medication and together with other medications for anesthesia. It has a rapid onset and effects generally last less than an hour or two. Fentanyl is available in a number of forms including by injection, as a skin patch, and to be absorbed through the tissues inside the mouth.
Common side effects include nausea, constipation, sleepiness, and confusion. Serious side effects may include a decreased effort to breathe (respiratory depression), serotonin syndrome, low blood pressure, or addiction. Fentanyl works in part by activating ?-opioid receptors. It is about 75 times stronger than morphine for a given amount Some fentanyl analogues may be as much as 10,000 times stronger than morphine.
Fentanyl was first made by Paul Janssen in 1960 and approved for medical use in the United States in 1968. It was developed by testing chemicals similar in structure to pethidine(meperidine) for opioid activity. In 2015, 1,600 kilograms (3,500 lb) were used globally.