Fentanyl is an opioid agonist, a potent narcotic analgesic, with pharmacological effects similar to those of morphine, with rapid analgesic effects but shorter duration. The respiratory depression of fentanyl is weaker than morphine, and the adverse effects are smaller than morphine. Indications: It is suitable for various pains and analgesia after and during surgery and gynecology, and can also be used to prevent or alleviate delirium after surgery, and can be used in combination with anesthetics as auxiliary anesthetics; it can be used in combination with haloperidol and other drugs to make “tranquilizer analgesic”, which is used for analgesia of large area change and minor surgery. Fentanyl is available in various dosage forms, such as injection and transdermal patch, so the dosage should be carefully referred to its instruction manual.