Quinupristin 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
Quinupristin
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.
These two medicines can interact. Simvastatin (Zocor) is a cholesterol-lowering statin. Your body clears it using a liver enzyme called CYP3A4. The antibiotic quinupristin strongly blocks that enzyme, so the simvastatin can build up higher than expected in your blood.
When statin levels rise, the main worry is your muscles. You might notice muscle pain, tenderness, or weakness. Rarely, severe muscle breakdown can happen. The good news is this is very manageable. Your care team can adjust your simvastatin dose and check your muscles and lab work while you take both. Let your pharmacist or doctor know about any new muscle aches.
Effect: Increased simvastatin exposure with elevated risk of myopathy/rhabdomyolysis.
Mechanism: Quinupristin/dalfopristin is a potent CYP3A4 inhibitor; simvastatin is a CYP3A4 substrate. Inhibition reduces first-pass and systemic clearance, raising simvastatin AUC/Cmax (active acid metabolite included). Direction is increased statin effect/toxicity.
Onset: Delayed. Evidence: Probable. Severity: Major.
- Monitor for muscle pain, tenderness, weakness.
- Check baseline and follow-up CK.
- Reduce/individualize simvastatin dose; discontinue if CK markedly elevated or myopathy/rhabdomyolysis suspected.
- Consider alternative agent if concurrent use is prolonged.
What happens
An increased risk of myopathy or rhabdomyolysis
Interaction Deep Dive
As a strong inhibitor of the cytochrome P450 3A4 enzyme system, quinupristin/dalfopristin can raise simvastatin levels when the two drugs are given together. Simvastatin doses should be modified as needed, and patients need careful observation for indications of excessive simvastatin adverse effects, including muscle weakness or pain1.
Why it happens (mechanism)
Inhibition of cytochrome P450-mediated metabolism of simvastatin
How to manage this interaction
This combination is manageable with a few precautions. Keep taking both medicines as prescribed unless your care team tells you otherwise.
- Your simvastatin dose may need to be adjusted and individualized by your care team while you are on the antibiotic.
- Your team may monitor you more closely, including checking a muscle enzyme blood test (creatine kinase, or CK).
- Report any muscle pain, tenderness, or weakness right away, especially if it comes with dark urine or feeling unwell.
Ask your pharmacist or prescriber before starting, stopping, or changing either drug.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Quinupristin and Simvastatin together?
Quinupristin can raise simvastatin levels and increase the risk of muscle injury, so your care team may adjust your statin dose and watch for muscle pain and CK changes. Report any new muscle pain or weakness promptly. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Quinupristin 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 "delayed". Effects tend to build up gradually over days to weeks.
How is the Quinupristin and Simvastatin interaction managed?
This combination is manageable with a few precautions. Keep taking both medicines as prescribed unless your care team tells you otherwise. Your simvastatin dose may need to be adjusted and individualized by your care team while you are on the antibiotic. Your team may monitor you more closely, including checking a muscle enzyme blood test (creatine kinase, or CK). Report any muscle pain, tendernes… 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 Quinupristin 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: Synercid(R) I.V. quinupristin and dalfopristin. Rhone-Poulenc Rorer Pharmaceuticals Inc. Collegeville, PA, 1999.
Keep reading about Simvastatin
Keep reading about Quinupristin
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