Fentanyl is a synthetic opioid analgesic, known for its rapid onset and short duration of action. It is a schedule II prescription drug, used primarily to treat patients with severe pain or to manage pain after surgery. Fentanyl works by binding to the body’s opioid receptors, increasing dopamine in the central nervous system, and producing a state of euphoria and relaxation. Medical fentanyl is precisely dosed, but the illegal use of fentanyl poses severe risks because it is difficult to gauge its purity and dosage, leading to a high incidence of fatal overdoses.