Methadone: Uses, Dosage, Side Effects and Precautions

Methadone is a long-acting opioid used under strict medical supervision. It is prescribed for severe, persistent pain that other treatments cannot control, and for the treatment of opioid addiction. It carries serious risks, including addiction, life-threatening breathing problems and dangerous heart rhythm changes. Pain treatment and addiction treatment follow different rules and dosing, and dose changes should only be made by qualified clinicians.

Methadone at a Glance

What Is Methadone and How Does It Work?

Methadone is a synthetic opioid. Like other opioids, it acts on opioid receptors in the brain and spinal cord to change how pain is perceived and, in addiction treatment, to ease opioid withdrawal. It stays active in the body for a long time, so full effects build up over several days and doses are changed slowly. It has also been described as having NMDA receptor activity, though this is not covered by the label sections available for this article.

Take this medicine only as advised by your doctor or healthcare professional. Do not start, stop, or change the dose on your own.

Uses of Methadone

Pain (US label)

Methadone tablets are indicated in the US for severe and persistent pain that requires an opioid and cannot be adequately treated with alternatives, including immediate-release opioids. They are not for as-needed use. In July 2025 the FDA required opioid pain medicines to remove the phrase “extended treatment period,” because it could imply safety over indefinitely long use.

Opioid addiction

Methadone is used for detoxification and maintenance treatment of opioid addiction, with appropriate social and medical services. In the US, these products must be dispensed through certified opioid treatment programs.

India

A 2018 review reports methadone has been legal for opioid dependence since 2007 and was approved for pain management in 2016. India’s national opioid substitution programme (NACO) mainly uses buprenorphine, and its 2021 guidelines describe methadone as used at a few sites, largely outside that programme. Current Indian availability, licensing and rules for methadone could not be confirmed from official sources, so US prescribing rules should not be assumed to apply in India.

Dosage and Administration

Dosing is individualized. The figures below are prescribing information from the sources named. They are not instructions for self-medication, and methadone dose changes require qualified clinical supervision.

Pain (US labels)

• Starting dose: US product labels (revised January 2024) state starting treatment with 2.5 mg by mouth every 8 to 12 hours. This was also in the 2021 label. The most recent revision (12/2025) updated dosing sections, so this should be confirmed against the latest label.

• Titration: increase slowly, no more often than every 3 to 5 days. Steady state and full analgesic effect are not reached until at least 3 to 5 days on a dose.

• Duration of effect: the label states the duration of analgesic action is 4 to 8 hours (based on single-dose studies).

• Converting from other opioids: the label gives conversion factors as percentages and states they are not an equianalgesic table. Deaths have occurred in opioid-tolerant patients during conversion, so conversion is a specialist task.

Opioid addiction, US label

• Initial single dose 20 to 30 mg under supervision, not exceeding 30 mg. The first-day total should not ordinarily exceed 40 mg.

• Clinical stability is most commonly achieved at 80 to 120 mg a day.

• Methadone for addiction is dispensed through certified programs.

Opioid addiction, UK (NHS)

• People usually start on 10 mg to 30 mg once a day. Many then take a regular dose of 60 mg to 120 mg a day. A key worker or pharmacist usually supervises dosing.

These are different systems and are not interchangeable.

Stopping and missed doses

Do not stop methadone suddenly or without talking to your prescriber. Never take two doses at the same time or an extra dose to make up for a missed one (NHS).

Monitoring

The US label advises close monitoring of people with risk factors for QT prolongation, cardiac conduction abnormalities or interacting medicines, including when starting and increasing the dose. It also advises regular reassessment of older, debilitated or chronic lung disease patients. The treating doctor decides what tests and follow-up are needed.

Side Effects

Common side effects (NHS: happen to more than 1 in 100 people): constipation, nausea or vomiting, drowsiness, dizziness, mild headache, feeling cold, excess sweating, and dry eyes, mouth or nose.

Less common but serious (NHS: fewer than 1 in 100): hallucinations, mood changes or confusion. Call 111 (UK) or seek medical advice.

Call emergency services immediately for:

• Any breathing problems, or being very drowsy and hard to wake

• An irregular heartbeat, or one faster or slower than usual

• Temporary vision loss or a constant throbbing headache that worsens when coughing or straining

• Signs of a serious allergic reaction, such as swelling of the lips, mouth, throat or tongue, or a tight throat

Overdose: too much methadone can make a person very sleepy and slow or stop their breathing. The NHS advises calling 999 and giving naloxone if you have access to it. The FDA’s 2025 class labeling update for opioid pain medicines names naloxone and nalmefene as overdose-reversal agents. Ask your doctor whether you should have one at home.

Other risks in the US label include opioid-induced hyperalgesia (increased pain sensitivity), serotonin syndrome with serotonergic medicines, and accidental ingestion, especially by children.

Contraindications and Precautions

Contraindications (US label): significant respiratory depression; acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment; known or suspected gastrointestinal obstruction, including paralytic ileus; hypersensitivity to methadone.

QT prolongation

The label’s boxed warning states that QT interval prolongation and serious arrhythmia (torsades de pointes) have occurred during treatment. Cases are more common, but not limited to, higher doses (above 200 mg a day). A lower dose is not risk-free.

Precautions

• Respiratory depression is more likely in older, debilitated or chronic lung disease patients.

• The NHS advises telling your doctor before starting if you have lung or breathing problems, heart disease or a heart rhythm problem, low blood pressure, head injury or bad headaches, ulcerative colitis, seizures, thyroid, adrenal, kidney or liver problems, myasthenia gravis, or a history of dependence on alcohol, medicines or drugs.

Drug Interactions

• Benzodiazepines, other CNS depressants and alcohol: profound sedation, respiratory depression, coma and death (US boxed warning). The NHS names sleep and anxiety medicines (for example temazepam, zopiclone, zolpidem, lorazepam, diazepam) and gabapentin or pregabalin to discuss with your doctor.

• CYP enzyme inhibitors: medicines that inhibit CYP3A4, 2B6, 2C19, 2C9 or 2D6 can raise methadone levels (examples in the US label include macrolides, azole antifungals, ritonavir, fluconazole, fluvoxamine and some SSRIs).

• CYP enzyme inducers: stopping inducers (examples include rifampin, carbamazepine, phenytoin, St John’s wort and phenobarbital) can also raise methadone levels. Both can cause fatal respiratory depression. Starting some inducers may lower methadone effect, and the NHS notes St John’s wort may stop methadone from reducing withdrawal symptoms properly.

• Drugs that affect heart rhythm or electrolytes: the US label lists potentially arrhythmogenic agents and medicines that cause electrolyte disturbances. The NHS names amiodarone, verapamil and diltiazem.

• Serotonergic medicines: risk of serotonin syndrome.

• MAOIs: the US label advises against use during treatment and within 14 days of stopping.

• Other opioids: the NHS says not to take morphine, buprenorphine, codeine or other opioids while taking methadone, including codeine-containing cough and cold products. The US label says to avoid mixed agonist/antagonist and partial agonist opioids because they may reduce pain relief or cause withdrawal.

• Antiretroviral medicines: may change effectiveness or toxicity (US label).

• Paracetamol, ibuprofen and aspirin are usually fine with methadone (NHS).

Tell your doctor or pharmacist about all prescription medicines, OTC medicines, supplements and herbal products you use. This list is not complete.

Pregnancy and Breastfeeding

• Pregnancy: the US label describes newborn opioid withdrawal syndrome as an expected and treatable outcome of use in pregnancy, which can be life-threatening if not recognised and treated. Methadone clearance may increase during pregnancy, so the dose may need to be changed (US label, NHS). If you take methadone near the end of pregnancy, your baby will be checked for withdrawal (NHS). Do not stop methadone without medical supervision.

• Breastfeeding: the US label advises monitoring breastfed infants for excess sleepiness and breathing difficulty. The NHS says breastfeeding is usually possible if your baby is healthy, only small amounts pass into milk, and you should not stop breastfeeding suddenly because the baby may have withdrawal symptoms. Do not share a bed with your baby while taking methadone (NHS). A specialist team can guide this decision.

Methadone Availability, Brands and Price in India

Reliable current information on Indian methadone brands, strengths, prices and availability could not be confirmed, so none is listed here. Methadone is a controlled medicine, and its use in India is governed by narcotics law and approved treatment settings. Ask your treating doctor or treatment programme.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have questions about this medicine, its side effects, or your treatment plan, you can consult a doctor through HealthPil.