NutriStack
Grapefruit Juice and Simvastatin, contraindicated.
Grapefruit juice inhibits intestinal CYP3A4 and can substantially increase simvastatin exposure, raising myopathy and rhabdomyolysis risk.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Substances
- Grapefruit Juice and Simvastatin
- Pair type
- Contraindicated
- Evidence (highest tier)
- Strong
- Source citations
- 1 source
- Stack Score effect
- −25 to your Stack Score (per scored contraindication row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Contraindicated · Strong evidence
Contraindicated
What is happening. Grapefruit juice inhibits intestinal CYP3A4 and can substantially increase simvastatin exposure, raising myopathy and rhabdomyolysis risk.
Mechanism. Furanocoumarins in grapefruit inhibit intestinal CYP3A4, reducing first-pass metabolism of simvastatin.
Recommendation. Avoid grapefruit and grapefruit juice while taking simvastatin unless your prescriber specifically says otherwise.
Sources (1)
Stack Score
How this pair moves the number.
Effect on the composite score
If both Grapefruit Juice and Simvastatin are in the same stack, this pair applies −25 to your Stack Score (per scored contraindication row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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