Methadone is part of a category called opioids. It was created by German doctors during World War II. When it arrived in the United States, it was used to treat people with extreme pain. Today, your doctor may use it as part of your treatment for an addiction to heroin or narcotic painkillers. It works a lot as morphine does. You can take it as a tablet, a powder, or a liquid. It must be prescribed by a doctor. People who take it illegally often inject it, which exposes them to diseases like HIV. Even though it’s safer than some other narcotics, your doctor should keep a close watch on you while you take methadone. Taking it can lead to addiction or abuse.