The short answer
St John’s wort may alter some diabetes medicines, but a harmful interaction with glipizide has not been demonstrated in the reviewed evidence. The closest clinical study used gliclazide, a different drug.
What this answer covers
Hypericum perforatum oral products with glipizide; extraction and constituent content matter. Gliclazide, glimepiride and glyburide are distinct medicines.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- glipizide
The closest study tested another sulfonylurea
In 21 healthy volunteers, St John’s wort reduced gliclazide exposure and increased its apparent clearance. This suggests an interaction with that medicine, but it does not measure glipizide exposure.
The glucose outcome was unchanged
Despite the gliclazide concentration change, the study found no significant change in measured glucose or insulin response. It therefore did not demonstrate clinical loss of diabetes control, even for the studied medicine.
Do not assign a direction from the herb name alone
Different medicines and St John’s wort preparations need separate assessment. The indirect study cannot tell us that glipizide levels rise, fall, or that a particular adverse event becomes more likely. Lack of direct evidence is not proof of safety.
Review starting and stopping
Discuss the exact product and amount with the diabetes team before starting or changing it. Follow your established glucose-monitoring and low-glucose treatment plan; do not adjust glipizide yourself. Give the clinician the full ingredients, including other medicines. No glipizide-specific dose adjustment or timing rule follows from this evidence.
Evidence and practical considerations
Absorption & effectiveness
Gliclazide pharmacokinetic findings are indirect and cannot establish glipizide absorption or efficacy changes.
- Exact scope
- Hypericum perforatum oral products with glipizide; extraction and constituent content matter. Gliclazide, glimepiride and glyburide are distinct medicines. with Oral glipizide RxCUI4821 IN, immediate and extended release distinguished.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- Exact source preparation, medication and endpoint limits apply; no universal dose change or spacing.
Factors that may matter: Formulation; Dose and duration; Meal pattern; Other glucose-lowering agents; Kidney and liver function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients with type 2 diabetes receiving glipizide.
Glipizide can cause severe hypoglycemia; added glucose-lowering agents warrant observation. Nicotinic acid can worsen glycemic control; withdrawal also needs observation.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Separate formulations and meal instructions; no automatic transfer of immediate-release antacid pharmacokinetics to XL. Does not establish a risk rate for these herbs.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients with type 2 diabetes receiving glipizide.
Glipizide can cause severe hypoglycemia; added glucose-lowering agents warrant observation. Nicotinic acid can worsen glycemic control; withdrawal also needs observation.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Separate formulations and meal instructions; no automatic transfer of immediate-release antacid pharmacokinetics to XL. Does not establish a risk rate for these herbs.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 21healthy volunteers.
Gliclazide AUC decreased to0.67 of control and apparent clearance increased; no significant glucose or insulin AUC change.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Gliclazide is not glipizide; exposure change did not demonstrate clinical loss of glucose control. No direct glipizide study identified.
Research assessment: · Open full citations ↗
Side effects & toxicity
No direct glipizide safety outcome; indirect gliclazide study had no significant glucose/insulin response change.
- Exact scope
- Hypericum perforatum oral products with glipizide; extraction and constituent content matter. Gliclazide, glimepiride and glyburide are distinct medicines. with Oral glipizide RxCUI4821 IN, immediate and extended release distinguished.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- Exact source preparation, medication and endpoint limits apply; no universal dose change or spacing.
Factors that may matter: Formulation; Dose and duration; Meal pattern; Other glucose-lowering agents; Kidney and liver function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients with type 2 diabetes receiving glipizide.
Glipizide can cause severe hypoglycemia; added glucose-lowering agents warrant observation. Nicotinic acid can worsen glycemic control; withdrawal also needs observation.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Separate formulations and meal instructions; no automatic transfer of immediate-release antacid pharmacokinetics to XL. Does not establish a risk rate for these herbs.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients with type 2 diabetes receiving glipizide.
Glipizide can cause severe hypoglycemia; added glucose-lowering agents warrant observation. Nicotinic acid can worsen glycemic control; withdrawal also needs observation.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Separate formulations and meal instructions; no automatic transfer of immediate-release antacid pharmacokinetics to XL. Does not establish a risk rate for these herbs.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 21healthy volunteers.
Gliclazide AUC decreased to0.67 of control and apparent clearance increased; no significant glucose or insulin AUC change.
How this applies: Exact glipizide formulation and supplement preparation matter; other sulfonylureas and glucose efficacy endpoints are not automatically glipizide hypoglycemia evidence.
Gliclazide is not glipizide; exposure change did not demonstrate clinical loss of glucose control. No direct glipizide study identified.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Prepared exact glipizide article preserving formulation, preparation and glucose endpoint distinctions. | |
| Research summary published |
Article revision: 3eafa382d2056901
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.