Buprenorphine and Mirtazapine: 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
Buprenorphine
Mirtazapine
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.
You've been prescribed buprenorphine (a pain or opioid-dependence medicine) along with mirtazapine (an antidepressant). Both can gently raise the body's serotonin levels, and both may slightly affect the heart's electrical timing (called the QT interval). Taken together, there is a theoretical chance of two problems: a reaction called serotonin syndrome, and an irregular heartbeat.
Signs to watch for include shivering, muscle twitching or stiffness, a racing heart, sweating, agitation, confusion, fever, or feeling faint. The good news is your care team can manage this well by keeping an eye on you, especially when you first start or change a dose. Please don't stop either medicine on your own, just let your doctor or pharmacist know how you're feeling.
Direction/mechanism: Additive risk. Both agents are serotonergic and both carry QTc-prolonging potential, so co-administration may additively increase risk of serotonin syndrome, QT prolongation, and torsades de pointes. Neither drug's effect on the other is via enzyme inhibition/induction here; the concern is pharmacodynamic additivity.
Evidence: Theoretical; mirtazapine QT/TdP signals are largely postmarketing, mostly with overdose, underlying cardiac disease/family history, or concomitant QT-prolonging drugs.
Management:
- Monitor for serotonin syndrome, especially at initiation and dose escalation.
- Consider ECG/electrolyte monitoring in patients with cardiac risk factors.
- If serotonin syndrome emerges, discontinue serotonergic agents and provide supportive care.
What happens
Increased risk of serotonin syndrome, an increased risk of QT interval prolongation and an increased risk of torsades de pointes
Interaction Deep Dive
Exercise caution when mirtazapine is given alongside other agents that extend the QTc interval, since doing so heightens the likelihood of QT prolongation and/or ventricular arrhythmias. Postmarketing experience has documented cases of QT prolongation, torsades de pointes, ventricular tachycardia, and sudden death involving mirtazapine, with most of these occurring in the setting of overdose, preexisting cardiovascular disease or a family history of QT prolongation, or the simultaneous use of a QTc-prolonging drug. When mirtazapine is combined with other serotonergic medications, the additive serotonergic activity can raise the risk of serotonin syndrome. Watch for signs of serotonin syndrome, particularly when starting therapy and when doses are raised, and should the patient develop symptoms, treat with mirtazapine and stop any concurrent serotonergic agent23. Serotonin syndrome can present with neuromuscular abnormalities, autonomic hyperactivity, and mental status changes, and it may be life-threatening. Should serotonin syndrome emerge once the responsible agents have been stopped, deliver supportive care along with any other therapy that may be required 1.
Why it happens (mechanism)
Additive serotonin effects; additive QT interval prolongation
How to manage this interaction
You can usually take both medicines together safely when your care team is aware and watching for problems.
- Keep taking both as prescribed unless your doctor tells you otherwise.
- Your team may monitor you more closely, especially when starting either drug or raising a dose, and doses may be adjusted and individualized for you.
- Watch for serotonin syndrome: shivering, tremor, muscle stiffness or twitching, fast heartbeat, sweating, diarrhea, agitation, or confusion.
- Tell your team about any heart rhythm problems, fainting, palpitations, or family history of QT issues.
If you develop severe or sudden symptoms like high fever, stiffness, or a racing/irregular heartbeat, seek urgent care right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) A 75-year-old woman developed symptoms consistent with serotonin syndrome within a few hours of beginning mirtazapine and shortly after discontinuing FLUoxetine. Her existing depression treatment consisted of FLUoxetine, chlorproMAZINE, and LORazepam. Because she was not responding, FLUoxetine was stopped and mirtazapine 30 mg/day was begun soon thereafter. Within a few hours of initiating mirtazapine, she developed dizziness, headache, nausea, dry mouth, and intense anxiety and agitation accompanied by suicidal ideas. Additional symptoms included difficulty walking, pronounced resting tremor of the hands, and insomnia. She grew progressively worse over the following 3 days. Mirtazapine was discontinued on day 5. Her symptoms improved the next day. FLUoxetine 20 mg/day was resumed on day 7, after which dizziness, nausea, headache, and agitation resolved over the ensuing days. Over the subsequent 10 days, tremor, anxiety, difficulty walking, dry mouth, and insomnia improved 4.
b) A 26-year-old woman with anorexia nervosa who had been taking fluvoxaMINE for 4 months developed symptoms of serotonin syndrome after mirtazapine was started. Over a period of 4 days following the start of mirtazapine 30 mg/day, she developed twitching, tremors, agitation, restlessness, and a sensation of "feeling like she could crawl out of her skin." The symptoms quickly advanced to twitching, tremors, and restlessness. She was admitted to the hospital with additional symptoms of diaphoresis, flushing, fasciculations, and nausea, and was treated with cyproheptadine, acetaminophen, and IV fluids. She stayed afebrile during the entire episode. The symptoms fully resolved within 24 hours 5.
c) Postmarketing reports have described mirtazapine in connection with QT prolongation, torsades de pointes, ventricular tachycardia, and sudden death, with most cases arising in the setting of overdose, known cardiovascular disease or a family history of QT prolongation, or concurrent use of mirtazapine with QTc-prolonging agents 23.
Common questions
Can I take Buprenorphine and Mirtazapine together?
Buprenorphine plus mirtazapine can theoretically add up to raise the risk of serotonin syndrome and heart rhythm problems, so keep taking both as prescribed but watch for symptoms and let your care team monitor you, especially when starting or adjusting a dose. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Buprenorphine and Mirtazapine 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 Buprenorphine and Mirtazapine interaction managed?
You can usually take both medicines together safely when your care team is aware and watching for problems. Keep taking both as prescribed unless your doctor tells you otherwise. Your team may monitor you more closely, especially when starting either drug or raising a dose, and doses may be adjusted and individualized for you. Watch for serotonin syndrome: shivering, tremor, muscle stiffness or tw… 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.
Questions for your pharmacist
- Does my dose of Buprenorphine or Mirtazapine 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 (5)
- Boyer EW & Shannon M: The serotonin syndrome. N Eng J Med 2005; 352(11):1112-1120. PubMed
- Product Information: REMERON(R) oral tablets, mirtazapine oral tablets. Merck Sharp & Dohme Corp (per FDA), Whitehouse Station, NJ, 2020. DailyMed
- Product Information: Mirtazapine oral film coated tablets, mirtazapine oral film coated tablets. Apotex Corp (per DailyMed), Weston, FL, 2024. DailyMed
- Benazzi F: Serotonin syndrome with mirtazapine-fluoxetine combination. Int J Geriatr Psychiatry 1998; 13(7):495-496. DOI
- Demers JC & Malone M: Serotonin syndrome induced by fluvoxamine and mirtazapine. Ann Pharmacother 2001; 35:1217-1220. PubMed
Keep reading about Buprenorphine
Keep reading about Mirtazapine
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