Methadone can be used to keep a person stable as they detox from their opioid addiction. It helps to alleviate withdrawal symptoms, so the patient isn’t tempted to relapse to relieve pain. When given in higher doses, it blocks the opioid receptors in the brain, so if the person relapses, they gain little benefit from the drug to which they are addicted.
One dose lasts 24 hours and using methadone on its own is unlikely to result in overdose. It’s administered orally, which also reduces harm for intravenous drug users. In its pure form, methadone doesn’t damage the body’s major organs and prolonged use won’t cause physical damage.
