What is methadone?

Methadone is a prescription opioid medicine with a range of uses, including treating chronic non-cancer and cancer pain and, more commonly, opioid dependence.

It is a common opioid agonist treatment (OAT). Those participating in a methadone treatment program are generally provided with a daily dose of the medicine in an oral solution or syrup, which is swallowed. Methadone is prescribed by a doctor as part of a treatment plan, with the dose and treatment duration based on the needs of the individual.

By providing a regular and stable opioid dose, methadone removes the need for additional opioids and helps to stabilise opioid-dependent individuals. Methadone can also promote changes in the routines and habits that may be associated with the use of heroin or other opioids. This can help a person achieve their treatment goals, which may be to become abstinent, or reduce their opioid use.

Opioid dependence treatment using methadone can be long-term, lasting months or years as a form of maintenance therapy, or short-term for approximately five to 14 days to treat withdrawal.

What are the effects?

Methadone is a synthetic opioid agonist that effects the brain in the same way as morphine and heroin.

The most common side effects of methadone include:

Sedation
Sweating
Constipation
Lowered sex drive
Aching muscles and joints
Itchy skin.

Less common side effects include:

Light headedness or dizziness
Narrowing of pupils
Impaired night vision
Shallow breathing.

Other side effects, such as loss of appetite, stomach pain, nausea and vomiting, can usually be reduced by adjusting the dose prescribed.

Methadone and buprenorphine maintenance have been extensively researched and are associated with substantial reductions in the risk of death, criminal behaviour and opioid use, as well as improvements in mental and physical health.

When taken as prescribed in regular doses as part of a treatment program, methadone generally has few long-term effects on health.

As with all opioids, methadone has been associated with non-medical use and fatal overdoses. Methadone (like other opioids) will slow down breathing, particularly in higher doses, or in people who are not tolerant to opioids.
The risk of overdose is increased when methadone is combined with other sedatives, like sleeping pills or alcohol.
Withdrawal from long-term use of methadone may produce some symptoms similar to those experienced through heroin withdrawal. Symptoms tend to be milder than for heroin but may occur over a longer period.
According to the Australian Institute of Health and Welfare, on a snapshot day in 2022, around 28,000 people received methadone as a pharmacotherapy treatment for opioid dependence. Methadone is the most commonly prescribed pharmacotherapy drug across all age groups, and the proportion of clients who receive methadone has increased with age.
The Illicit Drug Reporting System (IDRS) is an Australian monitoring system run by the National Drug and Alcohol Research Centre (NDARC) at UNSW Sydney that identifies emerging trends of local and national concern in illicit drug markets.

The Ecstasy and Related Drugs Reporting System (EDRS) is an Australian monitoring system run by NDARC that identifies emerging trends of local and national interest in ecstasy and related drug use, markets and harms.

The Pocket Guide to Drugs and Health is a publication authored by experts from NDARC that provides information for health professionals on the impact of drug use.

The Australian Institute of Health and Welfare collects information on alcohol and tobacco consumption, and illicit drug use among the general population in Australia.

The Australian Bureau of Statistics is Australia’s national statistical agency, providing official statistics on a range of economic, social, population and environmental matters of importance to Australia.
Australian Institute of Health and Welfare (2024). National Opioid Pharmacotherapy Statistics Annual Data collection. AIHW, Australian Government. Retrieved from: aihw.gov.au/reports/alcohol-other-drug-treatment-services/national-opioid-pharmacotherapy-statistics/contents/about

Darke, S., Lappin, J., & Farrell, M. (2024). The Clinician’s Guide to Illicit Drugs and Health (Revised Edition); London: Silverback Publishing.

Swift, W., Nielsen, S., Kaye S, et al (2017). A Quick Guide to Drugs & Alcohol. Third Edition. Drug Info, State Library of New South Wales.

Emergency information

If you, or someone around you, is experiencing undesired or distressing psychological or physical symptoms from the intake of alcohol or other drugs, please seek immediate medical attention.

If you need urgent help from ambulance services, call Triple Zero (000). If a person has been mixing drugs with alcohol or other drugs, tell the paramedic exactly what has been taken.

Services

For free and confidential advice about alcohol and other drugs, call the National Alcohol and Other Drug Hotline on 1800 250 015. The hotline will automatically direct you to the Alcohol and Drug Information Service in your state or territory.

Date published

2 Jun 2025

Resource type

Fact Sheets

Author

NDARC