Fosaprepitant and Diazepam Nasal Spray: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Fosaprepitant
Diazepam Nasal Spray
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 exposure to benzodiazepines and an increased risk of benzodiazepine-related adverse reactions
Interaction Deep Dive
Concomitant administration of aprepitant or fosaprepitant with benzodiazepines may increase the exposure to benzodiazepines metabolized by CYP3A4 and may increase the risk of adverse reactions. Monitor for benzodiazepine-related adverse reactions when administered concomitantly with aprepitant or fosaprepitant1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by aprepitant
Common questions
Can I take Fosaprepitant and Diazepam Nasal Spray together?
Increased exposure to benzodiazepines and an increased risk of benzodiazepine-related adverse reactions Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fosaprepitant and Diazepam Nasal Spray 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 Fosaprepitant or Diazepam Nasal Spray 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: FOCINVEZ intravenous injection, fosaprepitant intravenous injection. Spes Pharmaceuticals Inc (per FDA), North Brunswick, NJ, 2023. DailyMed
Keep reading about Fosaprepitant
Keep reading about Diazepam Nasal Spray
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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.
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