Fusidic Acid 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
Fusidic Acid
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.
Simvastatin (Zocor) lowers your cholesterol, and fusidic acid is an antibiotic. When taken together, the antibiotic slows down the way your body breaks down the statin. That means the statin can build up to higher levels than usual.
Higher statin levels raise the risk of muscle problems, called myopathy, and in rare cases a serious muscle breakdown called rhabdomyolysis. Watch for unexplained muscle pain, tenderness, weakness, or dark-colored urine. The good news is your care team knows about this combination and can manage it. Don't stop either medicine on your own, but do call your pharmacist or doctor if you notice any of these muscle symptoms.
Mechanism: Fusidic acid inhibits CYP3A4-mediated metabolism of simvastatin, increasing simvastatin (and active metabolite) exposure. Neither drug requires this pathway for activation, so raised statin levels translate directly to increased toxicity risk.
Effect: Elevated risk of dose-dependent myopathy and rhabdomyolysis. Onset is delayed; evidence is rated probable; severity major.
- Monitor for myalgia, muscle weakness/tenderness, and dark urine.
- Consider baseline and follow-up CK and renal function if symptoms arise.
- Statin dose may need to be reduced or the statin temporarily withheld during antibiotic therapy; individualize per care team.
What happens
An increased risk of myopathy or rhabdomyolysis
Interaction Deep Dive
Use care when simvastatin is given together with fusidic acid therapy. Rhabdomyolysis can occur as a consequence of this pairing41.
Why it happens (mechanism)
Inhibition by fusidic acid of cytochrome P450 3A4-mediated simvastatin metabolism
How to manage this interaction
This combination can be managed. Keep taking both medicines as prescribed unless your care team tells you otherwise.
- Your team may monitor you more closely for signs of statin toxicity during the antibiotic course.
- The simvastatin dose may need to be adjusted and individualized, or the statin may be paused while you take the antibiotic. Let your prescriber decide.
- Report any new muscle pain, tenderness, weakness, or dark (tea-colored) urine to your pharmacist or doctor right away.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
2 reports — tap to read
a) A single case report documents a patient on maintenance simvastatin 40 mg/day who developed nausea, abdominal discomfort and myalgia after receiving fusidic acid (250 mg three times daily) together with rifampicin (600 mg daily). The patient was dehydrated and had mild tenderness in the right upper quadrant. Laboratory findings were as follows: aspartate transaminase 1618 U/L; alanine transaminase 657 U/L; alkaline phosphatase 133 U/L; total bilirubin 29 mcmol/L; gamma-glutamyltransferase 37 U/L; urea 24.7 mmol/L; creatinine 0.35 mmol/L. The next day the patient's condition worsened, with widespread muscle pain and weakness. His serum creatine kinase reached 66710 U/L and myoglobinuria was observed. Stopping simvastatin produced prompt clinical improvement. His renal function normalized, with a serum creatine kinase of 1153 U/L and a creatinine of 0.12 mmol/L. Although fusidic acid is not recognized as an inhibitor of the cytochrome P450 3A4 enzyme system, this case raises that possibility 2.
b) Rhabdomyolysis has been reported in a patient given simvastatin and tacrolimus at the same time. A 51-year-old woman with insulin dependent diabetes mellitus and dialysis-dependent renal failure secondary to diabetic nephropathy underwent a pancreas-kidney transplant. The pancreas was removed 4 weeks afterward because of a hemorrhagic pancreatitis. Simvastatin 10 mg/day was begun 8 months later. Her other drugs included tacrolimus, aprednislone and azathioprine. The simvastatin dose was raised to 20 mg/day 4 months later owing to persistent hyperlipidemia. Ten days after that, fusidic acid (500 mg TID) was started for a soft tissue infection and osteomyelitis of the second left toe. Five weeks later the patient was hospitalized for muscle pain that had begun 2 weeks earlier. Her serum creatinine was 3 mg/dL (270 mcmol/L), creatinine clearance was 12 mL/min, and serum creatine kinase (CK) was 24,000 U/mL. The tacrolimus trough level 4 days before admission was 9.1 ng/mL (11.3 nanomol/L). Simvastatin and fusidic acid were stopped and renal function improved. She was discharged on day 13 with a creatinine clearance of 45 mL/min and a CK level of 298 U/L. Simvastatin was replaced with fluvastatin. Several months later another soft tissue infection developed and was treated with fusidic acid. No adverse effects arose with the fusidic acid and fluvastatin combination. Concurrent use of tacrolimus and simvastatin may increase a patient's risk of rhabdomyolysis 3.
Common questions
Can I take Fusidic Acid and Simvastatin together?
Fusidic acid can raise simvastatin levels and increase the risk of serious muscle problems, so watch for muscle pain or dark urine and let your care team adjust or pause the statin if needed. Don't stop either drug on your own. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Fusidic Acid 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 Fusidic Acid and Simvastatin interaction managed?
This combination can be managed. Keep taking both medicines as prescribed unless your care team tells you otherwise. Your team may monitor you more closely for signs of statin toxicity during the antibiotic course. The simvastatin dose may need to be adjusted and individualized, or the statin may be paused while you take the antibiotic. Let your prescriber decide. Report any new muscle pain, tende… 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 Fusidic Acid 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 (4)
- Kotanko P, Kirisits W, & Skrabal F: Rhabdomyolysis and acute renal graft impairment in a patient treated with simvastatin, tacrolimus, and fusidic acid (letter). Nephron 2002; 90:234-235. PubMed
- Yuen S & McGarity B: Rhabdomyolysis secondary to interaction of fusidic acid and simvastatin. MJA 2003; 179:172. PubMed
- Kotanko P, Kirisits W, & Skrabal: Rhabdomyolysis and acute renal graft impairment in a patient treated with simvastatin, tacrolimus, and fusidic acid. Nephron 2002; 90:234-235. PubMed
- Yuen S & McGarity B: Rhabdomyolysis secondary to interaction of fusidic acid and simvastatin (letter). MJA 2003; 179:172. PubMed
Keep reading about Simvastatin
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist