The short answer
There is not enough direct clinical evidence to say quercetin reduces omeprazole absorption or makes it work less well. Laboratory enzyme effects and studies using other drugs point in different directions. Review concentrated quercetin supplements, but do not treat a predicted mechanism as a proven omeprazole interaction.
What this answer covers
Oral quercetin supplements with omeprazole; ginkgo mixtures, quercetin glycosides and different drug probes are not interchangeable evidence.
- Supplement or preparation
- Quercetin
- Medication ingredient
- omeprazole
Why do interaction lists mention this combination?
Omeprazole is metabolized by enzymes that quercetin can affect in laboratory experiments. One study found inhibition of CYP2C19 and CYP3A4 using recombinant enzymes. That is a reason for investigation, but the experiment did not measure omeprazole in patients or show reduced intestinal absorption. A mechanism alone cannot establish whether reflux treatment will change.
What have human studies actually tested?
An 18-person study gave quercetin 500 mg daily for 13 days and then tested midazolam, a different medication. Exposure decreased in some genetic groups. This differs from the inhibition seen in laboratory testing and cannot be copied to omeprazole, whose metabolism and clinical use are different. No exact-pair clinical result was established in the checked sources.
Does a ginkgo study answer the question?
No. Ginkgo contains multiple constituents, and an omeprazole result with a ginkgo preparation cannot be assigned to quercetin alone. Likewise, a trial comparing a supplement formula against omeprazole would not test taking both together. The important distinction is the actual substances and co-use being studied, not a shared ingredient or enzyme name.
Should I change the dose or timing?
The evidence does not supply a validated gap, dose adjustment or universal avoidance rule for quercetin and omeprazole. Bring the quercetin amount and any blend ingredients to the pharmacist, especially if other medicines are involved. Uncertainty is neither proof of harm nor a safety clearance, and it is not a reason to increase or stop prescribed omeprazole yourself.
Evidence and practical considerations
Absorption & effectiveness
There is not enough direct clinical evidence to say quercetin reduces omeprazole absorption or makes it work less well. Laboratory enzyme effects and studies using other drugs point in different directions. Review concentrated quercetin supplements, but do not treat a predicted mechanism as a proven omeprazole interaction.
- Exact scope
- quercetin as a defined supplement, with dose and formulation retained with oral omeprazole delayed-release; not esomeprazole
- Medication form and route
- oral
- Timing or duration
- Laboratory exposure and an indirect 13-day human quercetin regimen; no exact omeprazole coadministration interval established.
What remains uncertain
- No direct exact-pair human outcome found. Recombinant enzyme and midazolam results cannot establish omeprazole direction or clinical effect.
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: quercetin as a defined supplement, with dose and formulation retained.
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 laboratory enzyme study
pmc.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Recombinant human CYP enzymes produced in insect cells; no treated patients.
Inhibited CYP2C19 and CYP3A4 in vitro; direction suggests possible slowed metabolism under these assay conditions.
How this applies: Mechanistic lead only; cannot support a claim of reduced omeprazole absorption or treatment failure. Counterparty scope for this package: quercetin as a defined supplement, with dose and formulation retained.
Not omeprazole coadministration and no clinical concentration, benefit or dose interval. Article discusses ginkgo studies that cannot be treated as quercetin-alone evidence.
Source 3: original human pharmacokinetic trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 18 healthy men in an open randomized two-period crossover study.
Reduced midazolam exposure in CYP3A5 expressers, interpreted as induction; contrasts with in-vitro inhibition.
How this applies: Indirect warning against predicting omeprazole direction from a generic CYP statement. Counterparty scope for this package: quercetin as a defined supplement, with dose and formulation retained.
Different medication and genotype-dependent result; no omeprazole clinical measurement. Abstract-only.
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: c25dab0c9eaf8e88
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.