Pharmaceutical fentanyl is a synthetic opioid pain reliever, approved for treating severe pain, typically advanced cancer pain. Fentanyl works by blocking pain receptors in the brain and increasing production of the happiness-inducing chemical dopamine. It is 50 to 100 times more potent than morphine and is prescribed in the form of transdermal patches or lozenges and can be diverted for misuse and abuse. Legal brands of Fentanyl may be seen as: Antiq, Duragesic, Sublimaze, Subsys, Abstral, Lazanda.
The image to the left shows the amount of each drug needed to cause the average person to overdose. Carfentanil, classified as a synthetic opioid and used to tranquilize large animals, is 10,000 times more potent than morphine and 100 times more potent than fentanyl.