Grazoprevir 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
Grazoprevir
No brand names on record
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.
You've been prescribed simvastatin (a cholesterol medicine) along with grazoprevir (a hepatitis C medicine). Taking them together may cause the amount of simvastatin in your blood to rise higher than usual. When statin levels climb, the main thing to watch for is muscle problems, like unusual muscle aches, tenderness, or weakness.
The good news is this concern is based mostly on theory, not on lots of real-world cases, and your care team can manage it easily. They may keep your simvastatin dose on the low side and check in with you. If you notice new muscle pain or weakness, just let your pharmacist or doctor know. Keep taking both medicines as prescribed unless they tell you otherwise.
Effect: Grazoprevir may increase simvastatin plasma concentrations, raising the risk of statin-associated adverse events (myopathy, rarely rhabdomyolysis).
Mechanism: Not established; likely inhibition of a hepatic uptake transporter (e.g., OATP1B) and/or metabolic pathways reducing simvastatin clearance. Simvastatin is the affected object drug (not a prodrug in a way that reverses this; its active acid also accumulates).
- Direction: Increased simvastatin exposure (AUC/Cmax)
- Onset: Unspecified
- Evidence: Theoretical
- Management: Use lowest necessary simvastatin dose; monitor for muscle pain, weakness, and consider CK if symptoms arise.
What happens
Increased statin plasma concentrations
Interaction Deep Dive
Taking grazoprevir together with statins can raise statin levels in the plasma, which may result in a higher risk of adverse events. When these agents are given together, administer the smallest statin dose that is required and watch patients for statin-related adverse events like myopathy1.
Why it happens (mechanism)
Unknown
How to manage this interaction
Your care team can manage this combination safely. Here is what they typically do and what you can do:
- Lowest effective dose: Your simvastatin dose may be kept low and individualized by your care team while you are on grazoprevir.
- Monitoring: Your team may watch you more closely for muscle-related side effects.
- Watch for symptoms: Report new or worsening muscle aches, tenderness, weakness, or dark-colored urine to your pharmacist or doctor.
- Keep taking both as prescribed unless your prescriber tells you to change anything.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Grazoprevir and Simvastatin together?
Grazoprevir can raise simvastatin levels and the risk of muscle side effects, so your team may keep the statin dose low and watch you more closely. Report any new muscle pain or weakness, and don't change either medicine on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Grazoprevir and Simvastatin interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Grazoprevir and Simvastatin interaction managed?
Your care team can manage this combination safely. Here is what they typically do and what you can do: Lowest effective dose: Your simvastatin dose may be kept low and individualized by your care team while you are on grazoprevir. Monitoring: Your team may watch you more closely for muscle-related side effects. Watch for symptoms: Report new or worsening muscle aches, tenderness, weakness, or dark… 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 Grazoprevir 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 anything you'd monitor while I'm on both?
References (1)
- Product Information: ZEPATIER(TM) oral tablets, elbasvir, grazoprevir oral tablets. Merck Sharp & Dohme Corp. (per manufacturer), Whitehouse Station, NJ, 2016. DailyMed
Keep reading about Simvastatin
Keep reading about Grazoprevir
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