Apixaban and Atazanavir: 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
Atazanavir
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.
Here's what's going on. Apixaban (Eliquis) is a blood thinner that helps prevent clots. Atazanavir (Reyataz) is an HIV medicine that can slow down how your body breaks down and clears apixaban. When apixaban builds up, its blood-thinning effect gets stronger, which raises your chance of bleeding, things like easy bruising, nosebleeds, or bleeding that is hard to stop.
The good news: this is very manageable. Your care team can adjust your apixaban dose and keep an eye on you for any signs of bleeding. Please don't change either medicine on your own, just check in with your pharmacist or doctor so they can tailor the plan for you.
Effect: Increased apixaban exposure and elevated bleeding risk.
Mechanism: Atazanavir (with or without ritonavir) inhibits both P-gp-mediated efflux and CYP3A4-mediated metabolism of apixaban, increasing apixaban AUC/Cmax. Apixaban is an active drug, not a prodrug, so inhibition amplifies its pharmacologic effect.
- Direction: Increased apixaban effect (pro-hemorrhagic).
- Evidence: Theoretical; severity rated major.
- Onset: Unspecified.
- Management: For apixaban 5 mg or 10 mg BID, reduce dose by 50% with combined P-gp/strong CYP3A4 inhibitors. For apixaban 2.5 mg BID, avoid coadministration. Monitor for bleeding.
What happens
Increased apixaban exposure and an increased risk of bleeding
Interaction Deep Dive
Giving atazanavir, whether or not ritonavir is also present, together with apixaban (an oral anticoagulant) can raise apixaban exposure, thereby heightening the potential for bleeding2. When apixaban 5 mg or 10 mg twice daily is combined with agents that act as both P-gp and strong CYP3A4 inhibitors, the apixaban dose should be cut by 50%. If apixaban is being taken at 2.5 mg twice daily, its use alongside combined P-gp and strong CYP3A4 inhibitors should be avoided1.
Why it happens (mechanism)
Inhibition of P-gp-mediated efflux transport of apixaban; inhibition of CYP3A-mediated metabolism of apixaban
How to manage this interaction
This can be managed safely with your care team's help. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your team may adjust your apixaban dose. If you take 5 mg or 10 mg twice daily, the labeled step is to lower the apixaban dose by half while on atazanavir.
- If you already take the low 2.5 mg twice-daily dose, this combination is generally avoided, so your prescriber may choose a different plan.
- Watch for and report signs of bleeding: unusual bruising, nosebleeds, blood in urine or stool, or bleeding that won't stop.
Talk with your pharmacist or doctor before making any change so they can individualize this for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Apixaban and Atazanavir together?
Atazanavir can raise apixaban levels and bleeding risk, so your care team may cut your apixaban dose in half or, at the low 2.5 mg dose, avoid the combination. Keep taking both as prescribed and check with your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Apixaban and Atazanavir 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 Atazanavir interaction managed?
This can be managed safely with your care team's help. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your team may adjust your apixaban dose. If you take 5 mg or 10 mg twice daily, the labeled step is to lower the apixaban dose by half while on atazanavir. If you already take the low 2.5 mg twice-daily dose, this combination is generally avoided, so y… 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 Apixaban or Atazanavir 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: ELIQUIS(R) oral film coated tablets, apixaban oral film coated tablets. Bristol-Myers Squibb Company (per Dailymed), Princeton, NJ, 2024. DailyMed
- Product Information: REYATAZ(R) oral capsules, oral powder, atazanavir oral capsules, oral powder. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2023. DailyMed
Keep reading about Atazanavir
Keep reading about Apixaban
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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