What it is used for

Opioid dependence, as an opioid substitution treatment
Severe pain, under a specialist
Cough in terminal illness (linctus, rarely)

Read our guides:

Drug dependence

Off-label uses

Doctors sometimes prescribe a medicine for a condition it is not officially licensed for. This is called off-label use. It is legal and common when there is good evidence it helps, and your doctor should explain why they are suggesting it.

Methadone is not commonly used off-label.

How it works

Methadone is a long-acting opioid. Taken once a day, it prevents withdrawal and reduces cravings for heroin and other opioids. It also blocks the high from other opioids.

Side effects

Like all medicines, Methadone can cause side effects, although not everyone gets them. Many are mild and ease after the first few weeks.

Common side effects

constipation
sweating
feeling sleepy
feeling sick
dry mouth
lower sex drive

Tell your doctor or pharmacist if these bother you or do not go away.

Serious side effects

These are rare. Call 111 or contact your doctor straight away if you get:

slow or shallow breathing, or being very sleepy and hard to wake. Call 999
a fast or irregular heartbeat, fainting or fits

Call 999 if you have signs of a serious allergic reaction, such as swelling of your lips, mouth, throat or tongue, or trouble breathing.

You can report any side effect to the Yellow Card scheme, run by the medicines regulator.

Stopping and withdrawal

Important safety information

Never take it with alcohol, benzodiazepines or other sedatives unless prescribed.
It can affect heart rhythm. You may need an ECG.
Keep it locked away. A small amount can kill a child or someone who does not usually take opioids.
Ask for naloxone, which can reverse an overdose.

Questions about your medicine?

A pharmacist can answer questions about your medicines for free, without an appointment. You can also ask your GP for a medication review. Check if you can get free prescriptions.