Ethinyl Estradiol and St Johns Wort

Supplement–drug interaction evidence from the TruthStack database.

SeverityCRITICAL
Evidence TierModerate
Interaction TypeCONTRAINDICATED
MechanismPHARMACOKINETIC
Last Reviewed2026-02-15

Summary

St. Johns Wort strongly induces CYP3A4 and P-glycoprotein, significantly reducing oral contraceptive levels. This causes CONTRACEPTIVE FAILURE — unintended pregnancy is well-documented. This is a high-risk combination. Discuss with your prescriber or pharmacist before combining. Use alternative contraception or discontinue St. Johns Wort.

Higher-Concern Contexts

This interaction may be of particular concern in the following contexts:

CYP Enzyme Profiles

Published CYP enzyme data for compounds in this interaction:

St Johns Wort: CYP1A2 inducer (moderate), CYP2C19 inducer (moderate), CYP2C9 inducer (moderate), CYP3A4 inducer (strong), P-gp inducer (strong)

API Reference

GET https://api.truthstack.co/v1/check?c1=ethinyl%20estradiol&c2=st%20johns%20wort

Open, unauthenticated. Returns JSON. Developer documentation

Related Interactions

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What this page is and is not. TruthStack is an informational reference database that describes published pharmacological findings. It does not provide medical advice, diagnosis, or treatment recommendations. The information on this page reflects flags in our database and should not replace consultation with a qualified healthcare provider. Always discuss supplement-drug combinations with your prescriber or pharmacist.