Apixaban and Ritonavir: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Aug 8, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Ritonavir
Apixaban
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.
Taking Ritonavir and Eliquis (apixaban) together needs a closer look. Eliquis is a blood thinner, and your body normally breaks it down and clears it at a steady pace. Ritonavir slows down that clearing process, so more Eliquis can build up in your blood than expected. That extra amount can raise your chance of bleeding, like easy bruising, nosebleeds, or bleeding that is harder to stop.
The good news: this is very manageable. Your care team may lower your Eliquis dose or choose a different plan, and they can watch you more closely. Please don't change anything on your own. Just check with your pharmacist or doctor so they can tailor the dose safely for you.
Mechanism: Ritonavir is a strong CYP3A4 inhibitor and P-gp inhibitor. Apixaban is a substrate of both CYP3A4 and P-gp (not a prodrug), so combined inhibition reduces its clearance and increases exposure.
- Direction/magnitude: Increased apixaban Cmax and AUC (ketoconazole reference data: Cmax +62%, AUC +97%), raising bleeding risk.
- Evidence: Probable; severity major.
- Management: Avoid coadministration when apixaban is dosed 2.5 mg BID. For 5 or 10 mg BID regimens, reduce apixaban by 50%. Monitor for signs of bleeding.
What happens
Increased apixaban exposure and an increased risk of bleeding
Interaction Deep Dive
When patients are taking apixaban at 2.5 mg orally twice daily, coadministration should be avoided. For patients on higher apixaban regimens (that is, 5 or 10 mg twice daily), reduce the dose by 50% when a combined P-gp and strong CYP3A4 inhibitor is used at the same time. Because apixaban is a substrate of both CYP3A4 and P-gp, taking it together with an agent that inhibits both P-gp and CYP3A4 strongly can raise apixaban exposure and thereby elevate bleeding risk 12. A pharmacokinetic study demonstrated that apixaban Cmax rose by 62% and AUC rose by 97% when it was given alongside ketoconazole (a combined P-gp and strong CYP3A4 inhibitor) 3.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism; inhibition of P-gp-mediated efflux transport of apixaban
How to manage this interaction
This interaction is manageable with your care team's help. Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise.
- If you take apixaban 2.5 mg twice daily, this combination is generally avoided, so your team may pick a different plan.
- If you take 5 or 10 mg twice daily, your dose may need to be reduced (by about half) and individualized by your care team.
- Your team may also monitor you more closely for bleeding.
- Watch for unusual bruising, nosebleeds, blood in urine or stool, or bleeding that won't stop, and report these promptly.
Talk with your pharmacist or doctor before making any changes.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) Giving apixaban together with ketoconazole produced a 62% rise in apixaban Cmax and a 97% rise in apixaban AUC relative to apixaban given by itself. A 10 mg oral dose of apixaban was given 4 days after the start of ketoconazole 400 mg once daily in 18 subjects 3.
b) In a drug interaction study, giving apixaban together with ketoconazole 400 mg raised apixaban Cmax and AUC by roughly 1.6-fold and 2-fold, respectively 2.
Common questions
Can I take Apixaban and Ritonavir together?
Ritonavir can raise apixaban levels and bleeding risk, so your dose may be reduced or the combination avoided. Don't change anything yourself; let your pharmacist or doctor tailor and monitor it. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Apixaban and Ritonavir 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 Apixaban and Ritonavir interaction managed?
This interaction is manageable with your care team's help. Keep taking both medications exactly as prescribed unless your prescriber tells you otherwise. If you take apixaban 2.5 mg twice daily, this combination is generally avoided, so your team may pick a different plan. If you take 5 or 10 mg twice daily, your dose may need to be reduced (by about half) and individualized by your care team. You… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Apixaban or Ritonavir 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 (3)
- Product Information: ELIQUIS(R) oral tablets, tablets for suspension, apixaban oral tablets, tablets for suspension. Bristol-Myers Squibb Company (per Manufacturer), Princeton, NJ, 2025. DailyMed
- Product Information: ELIQUIS(R) oral film coated tablets, apixaban oral film coated tablets. Bristol-Myers Squibb Company (per Dailymed), Princeton, NJ, 2024. DailyMed
- Frost CE, Byon W, Song Y, et al: Effect of ketoconazole and diltiazem on the pharmacokinetics of apixaban, an oral direct factor Xa inhibitor. Br J Clin Pharmacol 2015; 79(5):838-846.
Keep reading about Ritonavir
Keep reading about Apixaban
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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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