The short answer
St. John’s wort may reduce nateglinide’s glucose-lowering effect according to the medicine label. Have starting or stopping it supervised.
What this answer covers
Hypericum perforatum; extract composition and duration matter.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- nateglinide
Follow the exact label precaution
Nateglinide labeling names St. John’s wort among products that may reduce glucose lowering. The prescriber may recommend more frequent glucose checks and adjust treatment if needed; do not increase nateglinide yourself.
Other-drug studies give mixed context
St. John’s wort reduced gliclazide exposure in a human trial, but glucose and insulin measures did not significantly change. Another trial found no meaningful interaction with repaglinide. These medicines have different metabolic pathways from nateglinide.
A gap is not an established solution
No tested separation interval or supplement dose eliminates this concern. Bring the exact extract and a record of when it was started or stopped; do not interpret the warning as proof that the herb binds nateglinide in the gut.
Keep the prescribed medicine plan
Take nateglinide one to thirty minutes before meals as prescribed and skip its dose when a meal is skipped. Review supplement changes with the prescriber; do not move or increase the medicine to compensate for an unproven interaction.
Watch for low blood sugar
Follow your existing glucose-monitoring and low-blood-sugar treatment plan. New sweating, shakiness, hunger or confusion warrants a glucose check when possible. Severe confusion, a seizure or inability to swallow safely needs emergency help.
Evidence and practical considerations
Absorption & effectiveness
The current exact label explicitly includes St John’s wort among CYP inducers that may reduce nateglinide glucose lowering. Direct nateglinide-herb concentration changes or impaired intestinal absorption have not been measured in the reviewed originals.
- Exact scope
- Hypericum perforatum; extract composition and duration matter. with Exact nateglinide oral tablets. Exact RxNorm IN274332 oral nateglinide; CYP2C9 and CYP3A4 metabolism distinct from other meglitinides.
- Medication form and route
- oral
- Timing or duration
- Source-specific single-dose, repeated-dose and observational exposures distinguished.
What remains uncertain
- No exact-pair clinical study identified. Gliclazide exposure fell without a glucose AUC change; repaglinide had null PK/PD findings. These different drugs neither quantify nor negate the nateglinide label precaution.
Factors that may matter: preparation and plant part; clinical indication; dose; other medicines; baseline alertness.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed nateglinide.
Insulin secretagogue with hypoglycemia risk; take one to thirty minutes before meals and skip dose if meal skipped; CYP2C9/CYP3A4 pathways.
How this applies: Exact RxNorm IN274332 oral nateglinide; CYP2C9 and CYP3A4 metabolism distinct from other meglitinides.
No universal supplement dose, interval, event rate or untested formulation equivalence.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twenty-one healthy volunteers.
Gliclazide exposure decreased while glucose/insulin AUC did not change significantly.
How this applies: Only the named drug, preparation, route and measured endpoints apply.
Different drug; no nateglinide concentration or efficacy-loss measurement.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Fifteen healthy subjects with specified SLCO1B1 genotypes.
No significant effect on repaglinide exposure, glucose lowering or insulin response.
How this applies: Only the named drug, preparation, route and measured endpoints apply.
Repaglinide is not nateglinide; one preparation cannot negate the exact nateglinide label precaution.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Current exact available claims adjudicated using original captures and explicit identity and comparator limits. |
Article revision: 4695d1da3497c39b
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.