Methadone is a long-acting opioid prescribed by NHS drug services to treat heroin and opioid addiction. It works by occupying opioid receptors in the brain — eliminating withdrawal symptoms and cravings without the intoxicating cycle of heroin use. Methadone maintenance is free on the NHS and is one of the most evidence-based treatments available for opioid addiction, reducing overdose deaths by up to 50%.
Methadone is used primarily to treat heroin and opioid addiction as part of medication-assisted treatment (MAT) — also called opioid substitution therapy (OST). It occupies opioid receptors in the brain, eliminating heroin withdrawal symptoms and cravings without the intoxicating peaks and crashes of heroin or short-acting opioids. It is also used as a pain medication, though this is a separate application.
Methadone is a full opioid agonist — it activates the same receptors as heroin, codeine, and other opioids. Because it has a very long half-life (24–36 hours), a single daily dose provides stable opioid blood levels throughout the day. This eliminates the withdrawal-driven cycle of heroin use and allows people to live stable, functional lives. The dose is carefully calibrated by a prescriber to eliminate withdrawal without causing significant intoxication.
Methadone causes physical dependency — stopping suddenly causes withdrawal (similar to heroin withdrawal, but longer-lasting due to methadone's long half-life). However, "addiction" in the clinical sense — characterised by compulsive drug-seeking, loss of control, and harm — is the problem methadone is treating, not causing. People on stable methadone maintenance live functional, productive lives. The dependency on prescribed methadone is managed, not chaotic.
Being on a stable, prescribed dose of methadone does not automatically disqualify you from driving in the UK. DVLA guidance requires you to notify them if you are on methadone, and your prescriber may need to confirm your dose is stable and not impairing you. This is assessed on a case-by-case basis. If your dose is stable and you are not impaired, many people on methadone drive legally.
Research consistently shows that longer duration of methadone treatment produces better outcomes. Short-term methadone (less than 12 months) is associated with high relapse rates on cessation. Many people benefit from methadone maintenance for years or indefinitely. The decision to reduce and stop should be patient-led and gradual — very slow tapering over many months under medical supervision.
Common side effects include: constipation (very common), sweating, drowsiness (particularly in the early stages of finding the right dose), dry mouth, weight gain, and reduced libido. Cardiac effects (QT prolongation) are a risk at high doses — an ECG is usually done before starting high-dose methadone. Side effects typically diminish once a stable dose is established.