The short answer
Avoid taking St. John’s wort with omeprazole unless the prescriber has specifically reviewed the combination. Current omeprazole labeling advises avoiding co-use because St. John’s wort can substantially lower drug exposure. Taking them a few hours apart is not an established solution.
What this answer covers
Oral Hypericum perforatum tablets or supplements with oral omeprazole; effects of the tested botanical regimen do not establish every product’s magnitude.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- omeprazole
What did the human study find?
Twelve healthy men took St. John’s wort 300 mg three times daily for 14 days, then a 20 mg omeprazole capsule. Total omeprazole exposure fell approximately 38% or 44%, depending on the genetic metabolism group. This is direct human evidence of a pharmacokinetic change, although the study did not measure reflux relief or ulcer healing.
Why is a simple time gap unreliable?
The findings and current label point to increased drug-metabolizing enzyme activity after repeated St. John’s wort use. That is different from two tablets binding each other in the stomach. The trial did not test a protective morning-versus-evening schedule, and the label recommends avoiding the combination rather than giving an hourly separation instruction.
Do all St. John’s wort products act identically?
The study used one tablet regimen in a small selected group. Botanical composition can differ, and the inspected abstract does not provide enough preparation detail to assign an exact percentage to your bottle. The product’s uncertainty is a reason to review it, not a basis for assuming a different brand cannot interact.
What should I do if I already use both?
Tell the prescriber or pharmacist the product, daily amount, dates used and reason for taking St. John’s wort. Review the whole medication list before making changes, because the botanical can affect more than one treatment. Do not simply increase omeprazole to compensate; the checked evidence supplies no individualized replacement-dose calculation.
Evidence and practical considerations
Absorption & effectiveness
Avoid taking St. John’s wort with omeprazole unless the prescriber has specifically reviewed the combination. Current omeprazole labeling advises avoiding co-use because St. John’s wort can substantially lower drug exposure. Taking them a few hours apart is not an established solution.
- Exact scope
- oral St. John’s wort, tested as 300 mg tablets three times daily with oral omeprazole delayed-release; not esomeprazole
- Medication form and route
- oral
- Timing or duration
- Fourteen days of St. John’s wort before an oral omeprazole dose; no protective gap or recovery interval established.
What remains uncertain
- Small healthy male study with genotype subgroups; exact phytochemical content not available in the inspected abstract and no clinical healing endpoint.
Factors that may matter: exact preparation and dose; medication formulation and duration; other medicines and underlying conditions; source population and measured outcome.
Read the supporting source summaries
Source 1: regulatory product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral omeprazole delayed-release capsules.
Avoid St. John’s wort because it can lower omeprazole exposure. Long use may impair B12 absorption. Rare hypomagnesemia may require replacement and PPI discontinuation; consider monitoring in prolonged/high-risk use and preexisting hypocalcemia risk.
How this applies: Exact parent omeprazole RxCUI 7646, oral delayed-release form; not esomeprazole or a magnesium salt treated as a magnesium supplement. Counterparty scope for this package: oral St. John’s wort, tested as 300 mg tablets three times daily.
Label does not quantify exact risks for all supplements, establish a quercetin interaction, or require extra calcium/B12 for every user. Broad PPI adverse-event data are distinguished from exact-drug trials.
Source 2: original randomized crossover pharmacokinetic trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy men, six extensive and six poor CYP2C19 metabolizers.
Omeprazole AUC fell approximately 38% and 44% in the two genotype groups; peak fell approximately 38% and 50%, with metabolite changes consistent with induction.
How this applies: Exact oral omeprazole and one Hypericum tablet regimen; current label independently advises avoiding co-use. Counterparty scope for this package: oral St. John’s wort, tested as 300 mg tablets three times daily.
Abstract-only; exact phytochemical content not verified here. No reflux-healing endpoint or tested protective dosing gap.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Original evidence and current labels checked; complete private article and exact-current-claim adjudications prepared. | |
| Research summary published |
Article revision: 9702476341d3cfd9
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.