Simvastatin and Tadalafil: 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
Tadalafil
Simvastatin
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 both tadalafil (Cialis or Adcirca) and simvastatin (Zocor), a cholesterol medicine. Simvastatin can sometimes cause muscle problems on its own, and there is a report of one man who got serious muscle pain and weakness just a few hours after taking these two together. His muscle-related lab values went up, but everything returned to normal a few days after he stopped both drugs.
This is based on a single case, so it's not proven, but it's worth taking seriously. Please don't stop either medicine on your own. Watch for muscle pain, tenderness, or weakness, and let your pharmacist or doctor know so they can guide you safely.
Effect: Potential increased risk of myopathy/rhabdomyolysis with concomitant tadalafil and simvastatin.
- Mechanism: Unknown; a specific PK interaction is not clearly established.
- Evidence: Theoretical, based on a single case report (48-year-old male: muscle pain, proximal weakness, elevated CK, myoglobin, and transaminases 3 hours post-dose; resolved 5 days after discontinuing both).
- Onset: Rapid.
- Severity: Major.
Management: Avoid coadministration where possible. If used together, monitor for muscle pain, tenderness, or weakness, and check CK if myopathy is suspected. The statin dose and choice may be individualized by the care team.
What happens
An increased risk of myopathy
Interaction Deep Dive
A case report describes a 48-year-old man who experienced intense muscle pain along with weakness in the pelvic and shoulder regions 3 hours after he took tadalafil together with simvastatin. On admission, his levels of creatine kinase, myoglobin, and liver enzymes were raised. Five days after both drugs were stopped, his symptoms resolved and laboratory values normalized. The combination of simvastatin and tadalafil should not be used together1. When it is essential to give both drugs concurrently, the patient should be watched for signs and symptoms of myopathy.
Why it happens (mechanism)
Unknown
How to manage this interaction
The safest approach is often to avoid using these two together, so your care team may consider whether an alternative is appropriate. If you do need both, the situation is manageable with attention and monitoring.
- Keep taking both exactly as prescribed unless your doctor or pharmacist tells you otherwise.
- Watch for muscle pain, tenderness, cramping, or weakness, especially in your shoulders, hips, or thighs.
- Report dark or tea-colored urine or unusual fatigue promptly.
- Your team may check muscle-related lab work or adjust and individualize your statin choice or dose.
Bring this up at your next visit so your prescriber can tailor the plan for you.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) The combination of tadalafil and simvastatin produced myopathy in a 48-year-old man. His medical history included dyslipidemia and erectile dysfunction. He came to the emergency department reporting severe muscle pain in his lower limbs that started 3 hours after he took tadalafil. Roughly 8 days before admission, simvastatin 20 mg/day had been initiated. The pain progressively intensified in both the upper and lower extremities, accompanied by weakness in the pelvic and shoulder regions. On admission, examination was notable for worsening myalgia and penile erection. His creatine kinase level measured 326 units/L (normal range 38 to 190 units/L), and his myoglobin and liver enzyme levels were raised. Both tadalafil and simvastatin were stopped, after which the symptoms improved considerably and laboratory values normalized within 5 days. No other identifiable causes of the myalgias were found 1.
Common questions
Can I take Simvastatin and Tadalafil together?
Taking tadalafil with simvastatin may raise the risk of muscle injury, so this combination is best avoided when possible; if you take both, watch for muscle pain or weakness and tell your pharmacist or doctor. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Simvastatin and Tadalafil interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.
How is the Simvastatin and Tadalafil interaction managed?
The safest approach is often to avoid using these two together, so your care team may consider whether an alternative is appropriate. If you do need both, the situation is manageable with attention and monitoring. Keep taking both exactly as prescribed unless your doctor or pharmacist tells you otherwise. Watch for muscle pain, tenderness, cramping, or weakness, especially in your shoulders, hips,… 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 Simvastatin or Tadalafil 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)
- Gargante MP, Vacante M, Russo C, et al: Myopathy with concurrent tadalafil and simvastatin. Case Rep Med 2009; 2009:378287-. PubMed
Keep reading about Tadalafil
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.
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