Metoprolol and St Johns Wort

Supplement–drug interaction evidence from the TruthStack database.

SeverityMODERATE
Evidence TierLimited
Interaction TypeANTAGONISTIC
MechanismPHARMACODYNAMIC
Last Reviewed2026-02-10

Summary

Monitor closely. 25 serious adverse events reported with this combination in FDA FAERS. Pharmacovigilance signal, not proof of causation. Discuss with prescriber.

CYP Enzyme Profiles

Published CYP enzyme data for compounds in this interaction:

Metoprolol: CYP2D6 substrate (strong)

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

What We Don't Know

This interaction has limited evidence. Key gaps may include: direct clinical trial data for this specific combination, dose-response relationships, and long-term outcome data. Absence of evidence is not evidence of absence.

API Reference

GET https://api.truthstack.co/v1/check?c1=metoprolol&c2=st_johns_wort

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.