Resmetirom and Simvastatin: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 4, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Simvastatin
Resmetirom
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. Resmetirom (Rezdiffra) can cause your body to hold onto more simvastatin (Zocor) than usual. In a study, blood levels of simvastatin went up by nearly half to almost double when the two were taken together. More simvastatin in your system means a higher chance of statin side effects, like muscle aches, muscle weakness, or changes in your liver tests.
The good news is this is well understood and easy to plan around. Your care team can keep your simvastatin dose in a safe range and check on you as needed. Don't change anything on your own, just let your pharmacist or doctor know you take both so they can look after you.
Effect: Resmetirom increases simvastatin systemic exposure (Cmax ~1.4-fold, AUC ~1.7-fold with simvastatin 20 mg single dose plus resmetirom 100 mg/day at steady state in healthy subjects), raising the risk of statin-related toxicity.
- Direction: Increased simvastatin exposure (increases drug effect); neither agent is a prodrug requiring activation here.
- Severity/Evidence: Major; probable. Mechanism not fully characterized.
- Management: Limit simvastatin to a maximum of 20 mg/day when combined with resmetirom. Monitor for myopathy, rhabdomyolysis, and LFT elevations.
What happens
Increased simvastatin exposure and an increased risk of simvastatin-related adverse effects
Interaction Deep Dive
Taking resmetirom together with simvastatin raised simvastatin levels, potentially heightening the likelihood of adverse effects tied to simvastatin. In a study evaluating this interaction among healthy participants, giving a single 20 mg oral dose of simvastatin alongside resmetirom at steady state (100 mg/day) produced a 1.4-fold rise in simvastatin Cmax and a 1.7-fold rise in AUC. Cap the simvastatin dose at 20 mg per day when it is combined with resmetirom. Watch for statin-associated adverse reactions, such as (though not restricted to) raised liver tests, myopathy, and rhabdomyolysis1.
Why it happens (mechanism)
Unknown
How to manage this interaction
This interaction is manageable. Keep taking both medications exactly as prescribed unless your care team tells you otherwise.
- Your prescriber will typically limit simvastatin to no more than 20 mg per day while you are also taking resmetirom.
- Your team may monitor you more closely, including liver tests and watching for muscle problems.
- Report new or unusual muscle pain, tenderness, or weakness, dark urine, or unusual tiredness to your pharmacist or doctor promptly.
- Make sure both prescribers know you take these two together.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a study of drug interactions conducted in healthy subjects, the simvastatin Cmax rose 1.4-fold and the AUC rose 1.7-fold when a single oral 20 mg dose of simvastatin was given together with resmetirom at steady state (100 mg/day) 1.
Common questions
Can I take Resmetirom and Simvastatin together?
Resmetirom raises simvastatin levels, so simvastatin should usually be capped at 20 mg per day and you should watch for muscle pain or weakness. Keep taking both as prescribed and tell your pharmacist or doctor you take them together. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Resmetirom and Simvastatin 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 Resmetirom and Simvastatin interaction managed?
This interaction is manageable. Keep taking both medications exactly as prescribed unless your care team tells you otherwise. Your prescriber will typically limit simvastatin to no more than 20 mg per day while you are also taking resmetirom. Your team may monitor you more closely, including liver tests and watching for muscle problems. Report new or unusual muscle pain, tenderness, or weakness, d… 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 Resmetirom or Simvastatin 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: REZDIFFRA oral tablets, resmetirom oral tablets. Madrigal Pharmaceuticals, Inc. (per FDA), West Conshohocken, PA, 2025. DailyMed
Keep reading about Simvastatin
Keep reading about Resmetirom
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