Methadone, sold under the brand name Dolophine, among others, is an opioid used to treat pain and as maintenance therapy or to help with tapering in people with opioid dependence. Detoxification using methadone can either be done relatively rapidly in less than a month or gradually over as long as six months. While a single dose has a rapid effect, maximum effect can take five days of use. The effects last about six hours after a single dose. After long term use, in people with normal liver function, effects last 8 to 36 hours. Methadone is usually taken by mouth and rarely by injection into a muscle or vein.