NutriStack
Lovastatin and St. John's Wort, a conflict.
St. John's Wort can induce CYP3A4 and P-glycoprotein, which may lower exposure to CYP3A4-metabolized statins. Human data show a major reduction in simvastatin exposure, and lovastatin shares substantial CYP3A4 first-pass metabolism. This can make cholesterol control less reliable.
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
- Lovastatin and St. John's Wort
- Pair type
- Conflict
- Evidence (highest tier)
- Moderate
- Source citations
- 2 sources
- Stack Score effect
- −10 to your Stack Score (per scored conflict row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Conflict · Moderate evidence
Conflict
What is happening. St. John's Wort can induce CYP3A4 and P-glycoprotein, which may lower exposure to CYP3A4-metabolized statins. Human data show a major reduction in simvastatin exposure, and lovastatin shares substantial CYP3A4 first-pass metabolism. This can make cholesterol control less reliable.
Mechanism. Hyperforin in St. John's Wort activates pregnane X receptor signaling, inducing intestinal and hepatic CYP3A4 and P-gp. Lovastatin is a CYP3A4 substrate with extensive first-pass metabolism, so induction can reduce active statin exposure.
Recommendation. Avoid St. John's Wort while taking lovastatin unless your prescriber has explicitly approved it. If you have already combined them, tell your clinician and consider checking lipids after stopping St. John's Wort because induction can persist for days to weeks.
Sources (2)
- Sugimoto K, Ohmori M, Tsuruoka S, Nishiki K, Kawaguchi A, Harada K, et al. Different effects of St John's wort on the pharmacokinetics of simvastatin and pravastatin. Clin Pharmacol Ther. 2001;70(6):518-524. PMID 11753267
- Zhou S, Chan E, Pan SQ, Huang M, Lee EJ. Pharmacokinetic interactions of drugs with St John's wort. J Psychopharmacol. 2004;18(2):262-276. PMID 15260917
Stack Score
How this pair moves the number.
Effect on the composite score
If both Lovastatin and St. John's Wort are in the same stack, this pair applies −10 to your Stack Score (per scored conflict row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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