The short answer
A predictable reduction in flurazepam’s effect from St. John’s wort has not been established. Review the combination before use; studies with other sedatives do not define a safe interval or the effect on flurazepam’s long-lived active metabolite.
What this answer covers
Hypericum perforatum preparations; hyperforin content and duration vary.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- flurazepam
The direct interaction evidence is missing
St. John’s wort changes midazolam exposure in human studies, with preparation-dependent effects. Those studies do not measure flurazepam or its active metabolite and cannot prove the same change in sleep benefit.
The active metabolite needs separate consideration
Flurazepam forms an active metabolite that can accumulate and persist for days. A human cimetidine study showed that its disposition can change, but that different drug does not establish St. John’s wort’s effect.
Do not infer reduced absorption or a timing rule
The inspected evidence does not establish decreased intestinal uptake, a required avoidance interval or a way to prevent the interaction by separating doses. A metabolic hypothesis is not a measured clinical result.
Coordinate changes with the prescriber
Discuss the product before starting or stopping it. Do not compensate by taking more flurazepam or abruptly stopping prescribed treatment. Report changes in sleep, daytime impairment or unusual symptoms.
Evidence and practical considerations
Absorption & effectiveness
No exact human St John’s wort-flurazepam exposure/effectiveness or spacing evidence; other-drug CYP data cannot establish parent/active-metabolite direction. Individual review warranted without a universal timing claim.
- Exact scope
- Hypericum perforatum preparations; hyperforin content and duration vary. with Flurazepam4501 IN; oral hydrochloride capsules and active desalkyl metabolite.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No unmeasured pair incidence, blanket class transfer or arbitrary spacing interval.
Factors that may matter: Preparation; Dose; Other medicines; Organ function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed flurazepam
Additive CNS-depressant effects; active desalkyl metabolite accumulates and may persist for days.
How this applies: Exact flurazepam RxCUI 4501 IN, with stated salt/formulation/route bridge.
No named St John’s wort clinical interaction or universal botanical dose rule.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy volunteers.
Desalkylflurazepam exposure increased; peak concentration and time to peak were not significantly changed.
How this applies: Cimetidine is not St John’s wort; inhibitor results cannot be reversed into a measured induction effect.
Cimetidine is not St John’s wort; inhibitor results cannot be reversed into a measured induction effect.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults.
Short-term dosing had no measured CYP effect; repeated use reduced oral midazolam AUC more than IV AUC.
How this applies: Original source interpreted for flurazepam only within the stated preparation and endpoint limits.
Not a direct flurazepam combination trial; original preparation, dose and endpoint limits apply. No exact-pair adverse-event rate or protective spacing established.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 20 healthy men.
Small AUC decrease considered not clinically relevant by authors; no significant Cmax or half-life change.
How this applies: Original source interpreted for flurazepam only within the stated preparation and endpoint limits.
Not a direct flurazepam combination trial; original preparation, dose and endpoint limits apply. No exact-pair adverse-event rate or protective spacing established.
Research assessment: · Open full citations ↗
Timing & monitoring
No exact human St John’s wort-flurazepam exposure/effectiveness or spacing evidence; other-drug CYP data cannot establish parent/active-metabolite direction. Individual review warranted without a universal timing claim.
- Exact scope
- Hypericum perforatum preparations; hyperforin content and duration vary. with Flurazepam4501 IN; oral hydrochloride capsules and active desalkyl metabolite.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No unmeasured pair incidence, blanket class transfer or arbitrary spacing interval.
Factors that may matter: Preparation; Dose; Other medicines; Organ function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed flurazepam
Additive CNS-depressant effects; active desalkyl metabolite accumulates and may persist for days.
How this applies: Exact flurazepam RxCUI 4501 IN, with stated salt/formulation/route bridge.
No named St John’s wort clinical interaction or universal botanical dose rule.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy volunteers.
Desalkylflurazepam exposure increased; peak concentration and time to peak were not significantly changed.
How this applies: Cimetidine is not St John’s wort; inhibitor results cannot be reversed into a measured induction effect.
Cimetidine is not St John’s wort; inhibitor results cannot be reversed into a measured induction effect.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults.
Short-term dosing had no measured CYP effect; repeated use reduced oral midazolam AUC more than IV AUC.
How this applies: Original source interpreted for flurazepam only within the stated preparation and endpoint limits.
Not a direct flurazepam combination trial; original preparation, dose and endpoint limits apply. No exact-pair adverse-event rate or protective spacing established.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 20 healthy men.
Small AUC decrease considered not clinically relevant by authors; no significant Cmax or half-life change.
How this applies: Original source interpreted for flurazepam only within the stated preparation and endpoint limits.
Not a direct flurazepam combination trial; original preparation, dose and endpoint limits apply. No exact-pair adverse-event rate or protective spacing established.
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 | |
| Prepared exact flurazepam article with formulation-specific evidence and uncertainty. |
Article revision: 9f34d955c3a48956
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.