Order Phentermine Online | Buy Phentermine Online | Overnight Fedex | Credit Card | Methadone is given as a pill, a liquid, or a wafer. The typical dose is one per day. Under most circumstances, a person will experience pain relief from about 4-8 hours. The medication also blocks the effects that make one feel high from heroin, morphine, and even hydrocodone and oxycodone. It is also used to treat moderate to severe chronic pain.