Omeprazole and Conivaptan: 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
Conivaptan
Omeprazole
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.
Here's what's going on: Conivaptan (Vaprisol) can slow down a liver enzyme called CYP3A that helps your body break down other medicines. Omeprazole (Prilosec) is partly cleared by that same enzyme. So while you're on conivaptan, omeprazole may not clear as fast and its levels can build up a bit, which could increase its effects.
The good news is this is based mostly on theory rather than lots of real-world reports, and conivaptan is usually a short hospital treatment. Please don't change or stop either medicine on your own. Your care team can plan the timing and keep an eye on you so this is handled safely.
Mechanism: Conivaptan is a strong CYP3A inhibitor. Omeprazole undergoes hepatic metabolism partly via CYP3A4 (and CYP2C19). Inhibition may reduce omeprazole clearance and increase its systemic exposure (AUC).
- Direction: increased CYP3A substrate exposure (omeprazole effect enhanced).
- Magnitude: not quantified for omeprazole; conivaptan raised AUC of midazolam, simvastatin, and amlodipine.
- Onset: unspecified; evidence: theoretical.
- Management: manufacturer advises avoiding concomitant strong CYP3A substrates; a CYP3A substrate may be initiated no sooner than 1 week after completing conivaptan. Individualize and monitor.
What happens
Increased CYP3A substrate exposure
Interaction Deep Dive
Concurrent administration of conivaptan (a strong CYP3A inhibitor) with agents that depend chiefly on CYP3A-mediated metabolism for their clearance should be avoided, since this can raise the exposure of the CYP3A substrate. The AUC of the CYP3A substrates midazolam, simvastatin, and amLODIPine was increased by conivaptan. Starting the CYP3A substrate is permitted only after at least 1 week has elapsed following the end of conivaptan treatment1.
Why it happens (mechanism)
Inhibition of CYP3A-mediated substrate metabolism by conivaptan
How to manage this interaction
What your care team may do:
- Because conivaptan is usually a short course, your team may avoid overlapping it with omeprazole, or separate the timing.
- Guidance suggests a CYP3A-metabolized drug can be started no sooner than one week after conivaptan is finished.
- Your team may monitor you more closely while both are on board, and your dose may be adjusted and individualized as needed.
What you should do: Keep taking both as prescribed and let your pharmacist or prescriber know you are on both so they can plan the timing and watch for any increased side effects.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
3 reports — tap to read
a) The potent CYP3A inhibitor conivaptan, given at 40 mg/day IV, raised the AUC of midazolam, a CYP3A substrate, by roughly 100% when midazolam was administered as a 1 mg IV dose and by 200% when given as a 2 mg oral dose 1.
b) Conivaptan 30 mg/day IV increased the AUC of simvastatin, a CYP3A substrate, threefold 1.
c) Conivaptan 40 mg orally twice daily doubled both the AUC and the half-life of amLODIPine, a CYP3A substrate 1.
Common questions
Can I take Omeprazole and Conivaptan together?
Conivaptan can raise omeprazole levels by blocking CYP3A, so they generally shouldn't overlap; your care team may separate the timing (often starting the other drug at least a week after conivaptan) and monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Omeprazole and Conivaptan 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 Omeprazole and Conivaptan interaction managed?
What your care team may do: Because conivaptan is usually a short course, your team may avoid overlapping it with omeprazole, or separate the timing. Guidance suggests a CYP3A-metabolized drug can be started no sooner than one week after conivaptan is finished. Your team may monitor you more closely while both are on board, and your dose may be adjusted and individualized as needed. What you shoul… 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 Omeprazole or Conivaptan 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: VAPRISOL(R) intravenous injection, conivaptan HCl intravenous injection. Cumberland Pharmaceuticals Inc. (per manufacturer), Nashville, TN, 2014.
Keep reading about Conivaptan
Keep reading about Omeprazole
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.
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