Mirtazapine and Diazepam Rectal: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Mirtazapine
Diazepam Rectal
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.
What happens
Increased risk of somnolence
Interaction Deep Dive
Concomitant use of mirtazapine and any benzodiazepine should be avoided due to additive somnolent effects. When diazepam was coadministered with mirtazapine in healthy patients, diazepam had minimal effects on plasma levels of mirtazapine. However impaired motor skills is additive. Cautiously engage in activities that require alertness, including operating hazardous machinery and motor vehicles1.
Why it happens (mechanism)
Additive somnolent effects
Literature reports
1 report — tap to read
a) When diazepam 15 mg was coadministered with mirtazapine 15 mg in 12 healthy patients, diazepam had minimal effects on plasma levels of mirtazapine. However impaired motor skills is additive 1.
Common questions
Can I take Mirtazapine and Diazepam Rectal together?
Increased risk of somnolence Always confirm with your pharmacist or prescriber before making any change.
How serious is the Mirtazapine and Diazepam Rectal 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 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 Mirtazapine or Diazepam Rectal 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 (1)
- Product Information: REMERON(R) oral tablets, mirtazapine oral tablets. Merck Sharp & Dohme Corp (per FDA), Whitehouse Station, NJ, 2020. DailyMed
Keep reading about Mirtazapine
Keep reading about Diazepam Rectal
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