Drug Interaction Report

Lovastatin and Warfarin: Interaction Details

A pharmacist-reviewed analysis of the Lovastatin and Warfarin 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

Warfarin

Coumadin Jantoven
+

Lovastatin

Altocor® Altoprev Altoprev® Mevacor®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Moderate
Can be significant — usually manageable with monitoring.
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 127 documented Lovastatin interactions, 25 are rated moderate — including this one.
Onset
delayed
Evidence
probable
Severity
Moderate

What happens

An increased INR and increased risk of bleeding

Interaction Deep Dive

Concomitant use of warfarin and lovastatin may result in an increased risk of bleeding and/or increased INR. In postmarketing reports, there is clinically evident bleeding and/or increased INR in patients taking concomitant statins, including lovastatin, and warfarin. In patients taking warfarin, obtain an INR before starting lovastatin and frequently enough after initiation, dose titration or discontinuation to ensure that no significant alteration in INR occurs. Once the INR is stable, monitor INR at regularly recommended intervals1. Statin therapy in combination with warfarin is beneficial when clinically indicated with appropriate monitoring 2.

Why it happens (mechanism)

An unknown mechanism

Literature reports

1 report — tap to read

a) In postmarketing reports, there is clinically evident bleeding and/or increased INR in patients taking concomitant statins, including lovastatin, and warfarin 1.

Common questions

Can I take Lovastatin and Warfarin together?

An increased INR and increased risk of bleeding Always confirm with your pharmacist or prescriber before making any change.

How serious is the Lovastatin and Warfarin interaction?

It is rated moderate. Can be significant — usually manageable with monitoring.

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.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Lovastatin or Warfarin 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 anything you'd monitor while I'm on both?

References (2)

  1. Product Information: ALTOPREV(R) oral extended-release tablets, lovastatin oral extended-release tablets. Covis Pharma (per FDA), King of Prussia, PA, 2024. DailyMed
  2. Wiggins BS, Saseen JJ, Page RL, et al: Recommendations for management of clinically significant drug-drug interactions with statins and select agents used in patients with cardiovascular disease: a scientific statement from the American Heart Association. Circulation 2016; 134(21):e468-e495. PubMed
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Warfarin

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Lovastatin

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All Lovastatin interactions (127) Lovastatin drug information
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Beyond drug–drug

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:

Warfarin + Activated Charcoal Alfalfa American Ginseng Beer Cannabis Danshen Dong Quai Fasting + 353 more
Lovastatin + Activated Charcoal Apple Beer Grapefruit Siberian Cocklebur St. John's Wort Sweet Orange Wine + 176 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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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.