Methadone is part of a category of drugs called opioids. Methadone capsule changes the way your brain and nervous system respond to pain so that you feel relief. Its effects are slower than those of other strong painkillers like morphine. Your doctor may prescribe Methadone if you’re in a lot of pain from an injury, surgery, or long-term illness. Methadone comes in tablet, powder, and liquid forms. You have to have a prescription to get it. Your providers will give you the dose that should work best for you.