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Brand Name(s) : Physeptone, Synastone, Eptadone, Metharose, Methadose
Side Effects


Methadone should be used with caution in: elderly patients, patients with liver or kidney problems, adrenal gland problems, an enlarged prostate gland, low thyroid activity (hypothyroidism), alcoholics, those with epilepsy or a muscle weakness disease called myasthenia gravis, low blood pressure (hypotension), bowel problems (such as constipation), women who are breastfeeding or who are pregnant, those with low levels of potassium, sodium or magnesium in their blood, and anyone with heart disease, an irregular heart beat or family members who have suddenly died without cause.

It should not be used in: those with severe breathing problems, asthma (during an asthma attack), those dependent on (addicted) to non-opioid drugs, where there is a risk of severe constipation, those with a recent head injury, those at risk of paralytic ileus (a type of bowel instruction), in anyone who has taken monoamine oxidase inhibitor in the last 2 weeks, women in labour or children.

Also see list of precautions and interactions.


Store below 25°C. Protect from light.


Methadone is used to treat a number of problems.

It is a member of a class of drugs called opioid analgesics, sometimes known as a narcotic analgesics.

In general, this drug is used to treat severe pain or in drug addicts to treat their addiction to opioid drugs (such as heroin).

Benefits of being on this drug include the relief of pain and alleviation of addiction (dependency) on opioid drugs.

It is also used to suppress cough in patients who are terminally ill.

Listed below are the typical uses of methadone:

  • Severe pain
  • Cough in patients with a terminal disease
  • Opioid dependence (addiction).

However on occasion your doctor may prescribe this medicine to treat a condition not on this list.


How often do I take it?

  • Take this medication by mouth, intramuscular injection or subcutaneous injection usually every day, adjusted by response.
  • Use this medication regularly in order to get the most benefit from it.
  • Remember to use it at the same time each day - unless specifically told otherwise by your doctor.
  • It may take some time before the full benefit of this drug takes effect.
  • Certain medical conditions may require different dosage instructions as directed by your doctor.

What dose?

  • Dosage is based on your age, gender, medical condition, response to therapy, and use of certain interacting medicines.

Do I need to avoid anything?

  • Activities such as driving or operating machinery may be severely affected during and after treatment with methadone as it may cause drowsiness and reduce alertness. The time after which such activities may be safely resumed is extremely patient dependant and must be decided by your doctor. Consult your doctor or pharmacist for more details.

When can I stop?

  • It is important to continue taking this medication even if you feel well, unless your doctor tells you to stop.


  • Feeling sick (nausea)
  • Vomiting
  • Constipation
  • Excessive sweating
  • Feeling faint or dizzy when standing up
  • Small pupils
  • Growth of breasts and production of breast milk
  • Difficulty passing water (urine)
  • Dryness of the mouth and eyes or nose
  • Facial flushing
  • Drowsiness
  • Restlessness
  • Confusion
  • Changes in your mood such as feeling over excited
  • Hearing or seeing things that are not there (hallucinations)
  • Headache
  • Rashes
  • Feeling cold (hypothermia)
  • Reduced sexual urges
  • Painful periods or lack of periods.

If any of these persist or you consider them severe then inform your doctor.

Tell your doctor immediately if you develop any of the following symptoms: heart problems such as changes in the rate or way your heart beats (beating faster or a change in heart beat rhythm), any breathing difficulties or if your breathing becomes slow and shallow, if you asthma and it gets worse, worsening of the pressure inside your head if you have a head injury or brain disease.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine (which includes vaccines, herbals and over the counter medicines) that you are taking. It is run by the medicines safety watchdog called the Medicines and Healthcare products Regulatory agency (MHRA). Please report any suspected side effect on the Yellow Card Scheme website.


Before taking methadone, tell your doctor or pharmacist if you are allergic to it; or to other opioid analgesics; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a history in your family of anyone who has died suddenly without apparent cause, a personal history of heart disease including any sort of heartbeat irregularities, any recent head injury, if you are at risk of paralytic ileus, or if you have ever suffered from asthma.

Before using this medication, tell your doctor or pharmacist your medical history, especially any of the following: liver or kidney problems, adrenal gland problems, epilepsy, alcohol addiction, an under active thyroid gland (hypothyroidism), an enlarged prostate, low blood pressure (hypotension), bowel problems, myasthenia gravis (a muscle weakness disease), heart disease including any heartbeat irregularities, low levels of potassium, sodium or magnesium in your blood, or if you are pregnant or are breastfeeding.

Before having surgery, tell your doctor or dentist that you are taking this medication.

Does alcohol intake affect this drug?

  • Yes. Do not drink alcohol whilst taking methadone.

Pregnancy and breastfeeding - please ensure you read the detailed information below


Methadone is not safe to take if you are, or are planning to become, pregnant. Ask your doctor or pharmacist if you have any doubts or questions about this.

It is sensible to limit use of medication during pregnancy whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Methadone is not safe to take if you are breastfeeding. Ask your doctor or pharmacist if you have any doubts or questions about this.

It is sensible to limit use of medication during breastfeeding whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with them first.

This drug should not be used with the following medications because very serious, possibly fatal interactions may occur: monoamine oxidase inhibitors (MAOIs), amisulpride, saquinavir, vandetanib, lithium.

If you are currently using any of these medications, tell your doctor or pharmacist before starting methadone.

Before using this medication, tell your doctor or pharmacist of all prescription and non-prescription/herbal products you may use, especially of:

  • Antidepressants
  • St John's Wort
  • Drugs for insomnia
  • Tranquilisers
  • Anaesthetics
  • Antibiotics (e.g. rifampicin, ciprofloxacin, erythromycin)
  • Anti-epileptics (e.g. phenytoin, carbamazepine, phenobarbital, primidone)
  • Ketoconazole
  • Fluconazole
  • Cimetidine
  • Naloxone
  • Naltrexone
  • Buprenorphine
  • Treatments for HIV (e.g. nelfinavir, nevirapine, efavirenz)
  • Other narcotic painkillers (e.g. codeine)

This information does not contain all possible interactions. Therefore, before using methadone, tell your doctor or pharmacist of all the products you use.


Symptoms of an overdose include: slow shallow breathing (respiratory depression), extreme sleepiness progressing to coma (unable to wake), very small pupils, floppy muscles, cold/clammy skin, low blood pressure, and in severe overdosage, stopping breathing, heart attack and death.

If you think you, or someone you care for, might have accidentally taken more than the recommended dose of methadone or intentional overdose is suspected, contact your local hospital, GP or if in England call 111. In Scotland call NHS 24. In Wales, call NHS Direct Wales. In the case of medical emergencies, always dial 999.


If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

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Source: Selected from data included with permission and copyrighted by Boots UK Limited. This copyrighted material is sourced from a licensed data provider and is not for distribution, except as may be authorised by the applicable terms of use.
CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse events, nor should it be construed to indicate that use of a particular medicine is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any medicine, changing any diet, or discontinuing any course of treatment.

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