Drug Interaction Report

Midazolam Injection and Nelfinavir: Interaction Details

Name: Midazolam Injection and Nelfinavir Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Midazolam Injection and Nelfinavir interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Nelfinavir

Viracept

Midazolam Injection

Nayzilam Versed® Injection

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Contraindicated

These should generally not be used together.

Minor

Moderate

Major

Contraindicated

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.

Of 276 documented Midazolam Injection interactions, 22 are rated contraindicated — including this one.

Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.

Onset

delayed

Evidence

probable

Severity

Contraindicated

What happens

Increased midazolam exposure and an increase risk of prolonged sedation or respiratory depression

Interaction Deep Dive

Nelfinavir is a CYP3A inhibitor² and oral midazolam is a CYP3A4 substrate ¹. Due to the potential for serious midazolam adverse effects, including respiratory depression and increased or prolonged sedation, concomitant use of nelfinavir and orally administered midazolam is contraindicated ².

Why it happens (mechanism)

Inhibition of CYP3A-mediated metabolism of midazolam

Common questions

Can I take Midazolam Injection and Nelfinavir together?

Increased midazolam exposure and an increase risk of prolonged sedation or respiratory depression Always confirm with your pharmacist or prescriber before making any change.

How serious is the Midazolam Injection and Nelfinavir interaction?

It is rated contraindicated. These should generally not be used together.

How quickly could this interaction happen?

The documented onset is "delayed". Effects tend to build up gradually over days to weeks.

How strong is the evidence for this interaction?

The evidence is graded "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

Does my dose of Midazolam Injection or Nelfinavir 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 (2)

Product Information: midazolam hcl oral syrup, midazolam hcl oral syrup. Roxane Laboratories,Inc, Columbus, OH, 2007. DailyMed
Product Information: VIRACEPT(R) oral film coated tablets, oral powder, nelfinavir mesylate oral film coated tablets, oral powder. Pfizer Inc (per Dailymed), New York, NY, 2023. DailyMed

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Nelfinavir

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All Nelfinavir interactions (171)

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Midazolam Injection

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All Midazolam Injection interactions (276) Midazolam Injection drug information

Also serious with: Nirmatrelvir Ritonavir Saquinavir Telaprevir

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HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.