Side Effects Of Methadone

Like all medicines, methadone can cause side effects, but many people have no side effects or only minor ones.

You're more likely to get side effects if you are on a high dose of methadone.

Common side effects of methadone

These common side effects of methadone happen to more than 1 in 100 people. There are things you can do to help cope with them:

Speak to your doctor, pharmacist or key worker if the advice on how to cope does not help and a side effect is still bothering you or does not go away.

Serious side effects

Serious side effects happen in less than 1 in 100 people.

Call 111 now if you're seeing things that are not there (hallucinations), having changes in mood or feeling confused.

Call 999 if:

Do not drive yourself to A&E.

The person you speak to at 999 will give you advice about what to do.

Serious allergic reaction

It's possible to have a serious allergic reaction to methadone (anaphylaxis), but this is rare.

Call 999 now if:

• your lips, mouth, throat or tongue suddenly become swollen
• you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
• your throat feels tight or you're struggling to swallow
• your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
• you suddenly become very confused, drowsy or dizzy
• someone faints and cannot be woken up
• a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)

You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.

These can be signs of a serious allergic reaction and may need immediate treatment in hospital.

Other side effects

These are not all the side effects of methadone. For a full list, see the leaflet that comes with your medicine.

Reporting side effects

You can report any suspected side effect using the Yellow Card safety scheme.

Visit the Yellow Card website for more information about reporting side effects.

Sexual Health Advice

• Sexual Health Advice - Introduction and Overview
• The MenB vaccine that helps protect against gonorrhoea
• Sexual Health - Mpox and its dangers for Gay Men
• What happens when you visit an STI Clinic
• Ejaculation issues are common sexual problems in men
• The Male Menopause for men in their late 40s to early 50s
• Help and care if you have been Sexually Assaulted
• Mental health issues and self-harm are common amongst gay men