St Johns Wort and Theophylline

Supplement–drug interaction evidence from the TruthStack database.

SeverityCRITICAL
Evidence TierModerate
Interaction TypePHARMACODYNAMIC RISK
MechanismPHARMACOKINETIC
Last Reviewed2026-02-15

Summary

St. Johns Wort induces CYP1A2, reducing theophylline levels. Can cause loss of asthma/COPD control with life-threatening bronchospasm. Discuss with your prescriber or pharmacist.

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=st%20johns%20wort&c2=theophylline

Open, unauthenticated. Returns JSON. Developer documentation

Related Interactions

Methylene Blue + St. John'S Wort Clozapine + St Johns Wort Ethinyl Estradiol + St Johns Wort Phenytoin + St Johns Wort Amitriptyline + St Johns Wort Citalopram + St Johns Wort Escitalopram + St Johns Wort Fluoxetine + St Johns Wort
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.