Lansoprazole and St John's Wort: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
St John's Wort
No brand names on recordLansoprazole
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Decreased lansoprazole exposure
Interaction Deep Dive
Lansoprazole is extensively metabolized by CYP2C19 and CYP3A. Avoid concomitant use of lansoprazole with St John's wort (a CYP2C19 and CYP3A4 inducer) as decreased exposure to lansoprazole may occur12.
Why it happens (mechanism)
Induction of CYP2C19- and CYP3A-mediated lansoprazole metabolism by St John's wort
Common questions
Can I take Lansoprazole and St John's Wort together?
Decreased lansoprazole exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Lansoprazole and St John's Wort interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Lansoprazole or St John's Wort need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (2)
- Product Information: PREVACID(TM) oral delayed-release capsules, lansoprazole oral delayed-release capsules. Takeda Pharmaceuticals America Inc (per FDA), Deerfield, IL, 2017. DailyMed
- Product Information: PREVACID(TM) SoluTab oral delayed-release disintegrating tablets, lansoprazole oral delayed-release disintegrating tablets. Takeda Pharmaceuticals America Inc (per FDA), Deerfield, IL, 2017. DailyMed
Keep reading about St John's Wort
Keep reading about Lansoprazole
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist