Fentanyl is a powerful synthetic opioid that is similar to morphine but 50 to 100 times more potent. It is typically used to treat severe pain, such as the pain experienced by cancer patients. However, because it is so potent, fentanyl also has a high potential for abuse. When misused, fentanyl can cause a number of short- and long-term effects, including feelings of euphoria, drowsiness, and Sedation. It can also slow breathing and heart rate, which can lead to an overdose. Fentanyl is often mixed with other drugs, such as heroin or cocaine, which can amplify its effects and make an overdose more likely. As a result, fentanyl abuse is a serious problem that can have deadly consequences.