Methadone is used to treat moderate to severe pain when around-the-clock pain relief is needed for a long period of time. This medicine should not be used to treat pain that you only have once in a while or as needed. Methadone gives the brain a steady supply of opioid that stops withdrawal and cravings and blocks the high from heroin and fentanyl. Here is how it works. Methadone is a long-acting opioid medication that is used to reduce withdrawal symptoms in people addicted to heroin or other narcotic drugs, and it can also be used as a pain reliever. Methadone is a full opioid agonist, meaning it activates the same receptors in the brain that heroin, fentanyl, and prescription painkillers do. But it does so slowly and steadily, producing a long, flat effect rather than the sharp high and crash of shorter-acting opioids. Methadone is a medication approved by the Food and Drug Administration (FDA) to treat OUD as well as for pain management. When taken as prescribed, methadone is safe and effective. Find patient medical information for Methadone on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings In 2006, the U.S. Food and Drug Administration issued a caution about methadone, titled Methadone Use for Pain Control May Result in Death. The FDA also revised the drug's package insert. Methadone is a synthetic opioid medication used to treat moderate-to-severe chronic pain, as well as opioid use disorder. While methadone has legitimate medical uses, it also carries the potential for misuse, physical dependence, and addiction. Methadone, which is taken illegally, produces strong and prolonged effects. After consuming methadone in rehab, patients sometimes feel light euphoria, but only a few times when the dose has not been compiled yet. Methadone is a powerful drug used for pain relief and treatment of drug addiction. Learn more about what methadone is, why it’s used, side effects, risks, and how to store and dispose of it.