Drug interactions
Grapefruit + Simvastatin
Severity: Major
Grapefruit and Simvastatin: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Grapefruit juice inhibits intestinal CYP3A4 and markedly raises simvastatin exposure. This increases the risk of myopathy and rhabdomyolysis, particularly with large quantities.
What this interaction means in plain words
Grapefruit and Simvastatin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Furanocoumarins in grapefruit inhibit intestinal CYP3A4, reducing presystemic simvastatin metabolism.
What to do
Advise patients to avoid grapefruit and grapefruit juice while taking simvastatin, or choose a statin not dependent on CYP3A4.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Grapefruit and Simvastatin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
References
Other interactions of Simvastatin
- Atazanavir + Simvastatin Contraindicated
- Clarithromycin + Simvastatin Contraindicated
- Cobicistat + Simvastatin Contraindicated
- Cyclosporine + Simvastatin Contraindicated
- Cyclosporin + Simvastatin Contraindicated
- Danazol + Simvastatin Contraindicated
Frequently asked questions
Can I take Grapefruit with Simvastatin?
MediHelp rates the interaction as major. Grapefruit and Simvastatin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Grapefruit juice inhibits intestinal CYP3A4 and markedly raises simvastatin exposure. This increases the risk of myopathy and rhabdomyolysis, particularly with large quantities.
How serious is the interaction between Grapefruit and Simvastatin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise patients to avoid grapefruit and grapefruit juice while taking simvastatin, or choose a statin not dependent on CYP3A4.
What other medicines interact with Simvastatin?
MediHelp also lists interactions of Simvastatin with, for example, Atazanavir, Clarithromycin, Cobicistat. The full list is on the Simvastatin page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
