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Safety Checker/Interaction guides
Check a combinationScreen a stack for overlapping caution and interaction signals.Interaction guidesRead source-backed reviews for selected supplement and medication-class pairs.Understand interactionsLearn how pathway overlap, stacking, metabolism, and uncertainty affect risk.Safety checklistReview medication context, stacking, dose/form, and product-quality checks before buying.

Editorial interaction review

St. John's Wort and Hormonal Contraceptives: Interaction Evidence

Human interaction studies and authoritative safety guidance report that St. John's wort can alter exposure to hormonal contraceptive components. This is a medication-specific safety issue, not a theoretical supplement-stack overlap.

Evidence: DocumentedConfidence: higherMechanism: Pharmacokinetic

Why it is flagged

St. John's Wort + Hormonal contraceptives

Human interaction studies and authoritative safety guidance report that St. John's wort can alter exposure to hormonal contraceptive components. This is a medication-specific safety issue, not a theoretical supplement-stack overlap.

Interaction mechanism

Pharmacokinetic

The main interaction pathway is induction of drug-metabolizing systems, especially CYP3A-related metabolism, which can reduce exposure to some contraceptive components.

What remains uncertain

The magnitude depends on the contraceptive formulation, St. John’s wort extract and hyperforin content, dose, duration, adherence, and individual metabolism. This page does not estimate pregnancy risk for an individual.

Sources supporting this interaction review

Primary studies are labeled separately from authoritative secondary guidance so the evidence chain is visible.

  • NCCIH: St. John’s Wort — Usefulness and SafetyAuthoritative guidance
  • Pfrunder et al. randomized interaction study — PMID 14616430Primary source
  • Hall et al. clinical pharmacology interaction study — PMID 14663455Primary source

Screen this combination

Open the interactive checker with only the public ingredient slug and medication-class ID preselected. The URL does not contain personal medical information.

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Educational use only. This interaction review cannot determine whether a specific medication regimen is safe for an individual or replace medication-specific review by a pharmacist or clinician.