Methadone and Sertraline: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Methadone
Sertraline
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
Both methadone and sertraline can affect your body in some overlapping ways when taken together. Both can gently stretch out the heart's electrical rhythm (called the QT interval), and both raise a brain chemical called serotonin. When combined, that can raise the small chance of a serious reaction called serotonin syndrome (things like agitation, sweating, shaking, fast heartbeat). Sertraline may also slow how your body clears methadone, so methadone can build up and cause more drowsiness or slowed breathing.
The good news: your care team can manage this. They may watch you more closely and tailor your methadone dose. Keep taking both as prescribed and let your pharmacist or doctor know if you feel unusually sleepy, confused, or shaky.
Effect: Additive QT prolongation and serotonergic activity, plus possible increased methadone exposure via CYP2D6 inhibition by sertraline. Direction: increased methadone effect and increased risk of serotonin syndrome and torsadogenic potential. Neither is a prodrug here.
- Mechanism: Additive QTc prolongation; additive serotonergic effects; sertraline inhibition of CYP2D6-mediated methadone metabolism.
- Onset: Hours to days; evidence is largely theoretical.
- Severity: Major.
- Management: Monitor ECG/QTc and for serotonin syndrome, especially at initiation and dose changes. Monitor for respiratory depression and sedation. Consider methadone dose reduction until stable. Discontinue methadone if serotonin syndrome suspected.
What happens
Increased QT interval prolongation, increased risk of serotonin syndrome, increased methadone exposure and an increased risk of opioid adverse effects
Interaction Deep Dive
When methadone is combined with QT prolonging serotonergic CYP2D6 inhibitors, cases of serotonin syndrome have occurred along with a heightened likelihood of QT interval prolongation. Symptoms can appear anywhere from several hours to a few days after the drugs are used together. Furthermore, pairing methadone with a CYP2D6 inhibitor can raise methadone plasma concentrations, which may intensify or extend opioid effects and can lead to a fatal overdose, especially if the inhibitor is introduced once a stable methadone dose has already been established. Should concurrent use be required, watch closely for changes in cardiac conduction, the emergence of QT interval prolongation, and serotonin syndrome, particularly while starting therapy and adjusting the dose. Stop methadone if serotonin syndrome is suspected. A reduction in the methadone dose should be considered until stable clinical effects are reached. Check for respiratory depression and sedation at frequent intervals. If a CYP3A4 inhibitor is stopped, look for signs of opioid withdrawal and consider raising the methadone dose until stable clinical effects are attained123.
Why it happens (mechanism)
Additive QT interval prolongation; additive serotonergic effects; inhibition of CYP2D6-mediated methadone metabolism
How to manage this interaction
This combination is used in practice, and your care team can manage it safely by tailoring your treatment and watching you a bit more closely.
- Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise.
- Your team may check your heart rhythm (an ECG) and watch for sedation or slowed breathing, especially when either drug is started or the dose is changed.
- Your methadone dose may be adjusted and individualized until effects are stable.
- Call your pharmacist or doctor promptly if you notice agitation, confusion, fever, sweating, tremor, fast heartbeat, extreme drowsiness, or trouble breathing.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) A 28-year-old woman was admitted to a hospital for treatment of an acute worsening of asthma, and her stabilized drug regimen consisted of methadone 70 mg daily, diazePAM 2 mg twice daily, albuterol, ipratropium, raNITIdine, and spironolactone. She had begun taking fluvoxaMINE 100 mg daily three weeks prior to admission. After additional testing, her asthma was not judged to be in a substantial exacerbation, though hypoxemia and hypercapnia consistent with hypoventilation were noted. Methadone was reduced to 50 mg daily and diazePAM was stopped. Examination of a blood sample obtained at admission revealed a serum methadone concentration of 262 nanograms (ng)/mL. After twelve days, oxygenation had improved and the methadone concentration was recorded at 202 ng/mL. DiazePAM may have added to this interaction 4.
Common questions
Can I take Methadone and Sertraline together?
Methadone and sertraline together can add up to raise the risk of QT prolongation, serotonin syndrome, and higher methadone levels, so your care team may adjust your methadone dose and monitor you more closely; keep taking both as prescribed and report drowsiness, confusion, or shaking. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Methadone and Sertraline interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Methadone and Sertraline interaction managed?
This combination is used in practice, and your care team can manage it safely by tailoring your treatment and watching you a bit more closely. Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise. Your team may check your heart rhythm (an ECG) and watch for sedation or slowed breathing, especially when either drug is started or the dose is changed. Your met… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Methadone or Sertraline need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (4)
- Product Information: DISKETS dispersible tablets, methadone HCl dispersible tablets. Hikma Pharmaceuticals USA Inc (per FDA), Berkeley, NJ, 2023.
- Product Information: METHADOSE oral concentrate, methadone HCl oral concentrate. SpecGx LLC (per FDA), Webster Groves, MO, 2023. DailyMed
- Product Information: Methadone HCl injection, methadone HCl injection. Mylan Institutional LLC (per FDA), Morgantown, WV, 2023. DailyMed
- Alderman CP & Frith PA: Fluvoxamine-methadone interaction. Aust N Z J Psychiatry 1999; 33:99-101. PubMed
Keep reading about Methadone
Keep reading about Sertraline
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist