Supplement × Prescription·Evidence index
PubMed indexes 4 records that name Simvastatin and St. John's Wort together, either in the title or in an interaction, co-administration, or pharmacokinetic context. Each one is listed below with its study design and, where the abstract states one, the authors’ own conclusion, quoted and linked. This page reports that literature. It does not tell you whether to combine them.
Every statement below is attributed to a named, dated, linked source.
This page lists published research relevant to Simvastatin and St. John's Wort. It deliberately does not state whether the combination is safe, whether it interacts, in which direction, at what dose, or how far apart to take them.
Strongest relevance first: papers naming both substances in the title, then human trials and systematic reviews.
“Products containing St John's Wort should not be given to patients with hypercholesterolemia who are on treatment with simvastatin.”
Names both Simvastatin and St. John's Wort in its title.
“This study showed that St John's Wort decreases plasma concentrations of simvastatin but not of pravastatin. Because simvastatin is extensively metabolized by CYP3A4 in the intestinal wall and liver, which are induced by St John's Wort, it is likely that this interaction is partly caused by the enhancement of the CYP3A4-mediated first-pass metabolism of simvastatin in the small intestine and liver.”
Names both Simvastatin and St. John's Wort in its title.
“Numerous interactions between herbal medicines and conventional drugs have been documented. While the significance of many interactions is uncertain, several interactions, particularly those with St John's wort, may have serious clinical consequences.”
Names Simvastatin and St. John's Wort together in an interaction, co-administration, or pharmacokinetic context.
Names Simvastatin and St. John's Wort together in an interaction, co-administration, or pharmacokinetic context.
Search-based evidence indexes have real limits, and it is worth being explicit about them:
NutriStack is a free iPhone app for organising a supplement routine: what you take, when, and what the published record says about it. Its exploratory interaction checker covers Simvastatin, St. John's Wort, and several hundred other substances.
The checker is a research and organisation tool, not a clinical decision aid, and its per-pair assessments are excluded from search until they pass claim-level review.
NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.
