Methadone Syrup Consumer Medicine Information

Methadone hydrochloride 5mg/ml

What is in this leaflet

Please read this leaflet carefully.

This document answers some common questions about Methadone syrup. It does not contain all the available information.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you taking Methadone against the benefits he or she expects it will have.

If you have any concerns about taking this medicine ask your doctor or pharmacist.

What is Methadone syrup used for?

Methadone is an opioid analgesic, which means that it is used to treat or prevent pain. It is also used to treat a person's addiction to opioid drugs.

Your doctor may have prescribed it for another reason.

An opioid is a drug with addictive properties which has physical effects on the body.

How Methadone works

Methadone is a synthetic drug that produces effects similar to morphine although the feeling of euphoria (extreme happiness) is less than that experienced with morphine.

Doses are very slowly reduced until the patient does not need Methadone any more (total withdrawal). This process can take some time.

If taken for long periods of time, methadone can be addictive.

Before you take Methadone syrup

When Methadone should NOT be used

Do not take Methadone if you:

  • Have previously had an allergic reaction to Methadone syrup or any of the ingredients of Methadone, which are listed at the end of this document.
  • Suffer from shallow breathing.
  • Suffer from bronchial asthma (Methadone should not be taken when you have a bronchial asthma attack).
  • You drink large amounts of alcohol or you are an alcoholic.
  • Have recently suffered an injury to your head.
  • Are taking any other medications, especially antidepressants known as Monoamine Oxidase Inhibitors or you stopped taking an antidepressant in the last 14 days.
  • You suffer from an inflamed colon and have diarrhoea, stomach pains and/or fever.
  • Have, or have had, any problems with your bile duct or kidneys.
  • You have or have had liver problems.
  • Do not take Methadone after the expiry date (EXP) printed on the packaging.
  • Do not take Methadone if the packaging is torn or shows signs of interference, or the syrup look discoloured.

Before you start taking Methadone syrup

Tell your doctor if:

  • You suffer from thyroid problems.
  • You have problems with your adrenal or pituitary gland
  • You have problems with your prostate
  • You have diabetes mellitus, a condition where your blood sugar is too high and needs to be controlled with insulin.
  • Are pregnant, planning to become pregnant or breastfeeding. Your doctor will weigh up the risk of taking Methadone to your unborn baby and the benefit it will have for you. Methadone may cause difficulty breathing in the newborn baby.

Taking other medicines

Some medicines may affect the way others work.

Tell your doctor if you are taking any other medicines, including the oral contraceptive pill or medicines you buy without a prescription from a pharmacy, supermarket or health food shop.

If you are taking any of the following medicines, please let your doctor know:

  • Monoamine Oxidase Inhibitors- medicines used to treat depression such as moclobemide (Aurorix), phenelzine (Nardil), tranylcypromine (Parnate).
  • Rifampicin, an antibiotic (Rifadin, Rifinah)
  • Medicines used to treat epilepsy such as Phenytoin (Dilantin), and barbiturates (hypno-sedative drugs such as phenobarbitone)
  • Antipsychotic medications such as haloperidol (Haldol), chlorpromazine (Largactil), lithium (Lithicarb) etc.
  • Tranquilizers (medicines to calm you down)
  • Propranolol (Angilol, Cardinol), a medicine used to treat high blood pressure and angina.

How do I take Methadone

Methadone should not be given to children under 18 years of age unless told to by their doctor.

Methadone syrup is taken by mouth daily.

Your doctor may prescribe a starting dose of 10-20mg and then increase it by 5-10mg daily. The maximum daily dose is 80mg. Your dose will be individualised by your doctor.

Your dose will then slowly be decreased until total withdrawal from the opioid drug is achieved.

Elderly patients may be prescribed lower doses of Methadone as it can affect them more than younger patients.

While you are taking Methadone

Things you must do

  • Tell your doctor if you feel that Methadone is not helping your condition.
  • Tell your doctor if you become pregnant or you are breastfeeding.
  • Tell your doctor if you are taking any other medications including those you buy without a prescription from a pharmacy or health food shop.

Things you must not do

Methadone can make you sleepy. Do not drive a motor vehicle or operate any machinery until you know how Methadone affects you.

Do not drink alcohol as alcohol may enhance the effects of methadone such as slowing down your breathing, lowering your blood pressure so you feel tired and weak, dizzy.

Do not give this medicine to anyone else.

Taking too much Methadone (Overdose)

If you accidentally take more syrup than you have been told to take, contact your doctor, nearest hospital, emergency clinic or poisons centre (0800 POISON or 0800 764 766).

Keep telephone numbers for these places handy.

If you are not sure what to do, contact your doctor or pharmacist.

The symptoms and signs of an overdose include:

  • Very shallow breathing
  • The pupils (black centres) of the eyes become very small
  • Low blood pressure resulting in dizziness and light-headedness

Without treatment, a Methadone overdose can lead to coma (becoming unconscious).

Side effects

Tell your doctor or pharmacist as soon as possible if you have any problems while using Methadone, even if you think the problems are NOT connected with the medicine or are NOT LISTED in this document.

Like other medicines, Methadone can cause some side-effects. If they occur they are most likely to be minor and temporary. However, some may be serious and need medical attention.

Some reported side effects are:

  • Shallow breathing.
  • Nausea
  • Vomiting
  • Dizziness and feeling light headed
  • Drowsiness (feeling sleepy), fatigue, weakness
  • Dry mouth
  • Sweating
  • Feeling confused
  • Passing urine less often
  • Euphoria (feeling happy)

If you think you are having an allergic (hypersensitivity) reaction to Methadone, TELL YOUR DOCTOR IMMEDIATELY. Symptoms include:

  • Severe skin rash, itching or hives
  • Swelling of the face, lips, mouth or throat
  • Difficulty breathing and swallowing
  • Fever
  • Low blood pressure resulting in dizziness and light-headedness

Prolonged use of methadone in men sometimes causes enlargement of the breasts.

If any of these side effects persist, or are troublesome, see your doctor or pharmacist.

Product description

Methadone is a bright amber coloured liquid with a strong, pleasant smell. It is taken by mouth.


Methadone Hydrochloride, Sodium Benzoate, Ethanol 95%, Sorbitol solution, Glycerol, Caramel Flavour, Purified water.

Further information

Your doctor or pharmacist is the best person to give you advice on the use of Methadone and the treatment of your condition. You may also be able to find general information from other sources such as books in public libraries.

The information provided in this document applies only to Methadone syrup.

Methadone syrup is a trademark of the Glaxo Wellcome Group of Companies.

Issue 1, prepared September 2000