The short answer
St. John's wort is not recommended with clozapine. It can lower clozapine levels and may worsen symptom control. Stopping St. John's wort can raise clozapine levels, so any start, stop, or product change needs prescriber involvement. No hour-based separation or fixed washout period has been established.
What this answer covers
Applies to Hypericum perforatum, commonly called St. John's wort. Product strength varies, and the evidence does not define a safe preparation, dose, or washout interval.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- clozapine
Why this combination is avoided
The current clozapine label names St. John's wort as a strong CYP3A4 inducer and says concomitant use is not recommended. This is specific guidance for the named botanical, not a general statement about every herbal product. Product strength can vary, so a product name alone does not establish a predictable clozapine effect.
What the direct case reported
A case report described a woman with previously stable clozapine levels and clinical status who worsened after St. John's wort was added. The abstract reports lower clozapine levels and recovery after the botanical was withdrawn. It does not give the product formulation, dose, duration, exact clozapine values, or a schedule that can be copied.
Starting and stopping both matter
The concern is not solved by taking doses at different times of day. The label warns that stopping an inducer can raise clozapine levels, while use can lower them. Contact the clozapine prescriber before starting, stopping, or changing St. John's wort so any monitoring or medication adjustment is managed safely.
Plan any changes with your prescriber
No hour-based separation or fixed washout period was established by the label or the case report. Do not stop clozapine or change its dose independently to accommodate St. John's wort. If a product already contains Hypericum perforatum, bring the exact label to the prescriber or pharmacist for a plan based on the actual product and current treatment.
Evidence and practical considerations
Timing & monitoring
St. John's wort is not recommended with clozapine; starting or stopping it requires prescriber involvement because clozapine levels can change.
- Exact scope
- Hypericum perforatum, commonly called St. John's wort. with Clozapine.
- Medication form and route
- oral clozapine; oral botanical products
- Timing or duration
- No evidence-based hour separation or fixed washout period is established.
What remains uncertain
- The case report does not specify product, dose, duration, level values, or washout.
Factors that may matter: product strength; starting or stopping the botanical; clozapine-level monitoring.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed clozapine.
Concomitant use is not recommended. Stopping an inducer can raise clozapine levels and may require prescriber-directed adjustment.
How this applies: Direct exact-medication and named-botanical guidance.
No hour-based separation, fixed washout, or universal botanical dose is given.
Source 2: case report
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: A female patient whose clozapine levels and clinical status had been stable.
The abstract reports lower clozapine levels and worsened clinical status after St. John's wort, with recovery after withdrawal.
How this applies: Direct named botanical and clozapine case evidence for lower levels and clinical worsening, bounded by missing regimen details.
Single case with abstract-only details; no exact product, dose, level, duration, or washout can be inferred.
Research assessment: · Open full citations ↗
Absorption & effectiveness
St. John's wort can reduce clozapine levels and may worsen clinical control; reduced absorption was not established.
- Exact scope
- Hypericum perforatum products, whose preparations vary. with Clozapine.
- Medication form and route
- oral clozapine; oral botanical products
- Timing or duration
- Exact timing and duration are not reported in the direct case abstract.
What remains uncertain
- One abstract-only case provides no exact regimen or concentration values.
Factors that may matter: product preparation; starting or stopping the botanical; prescriber-directed monitoring.
Read the supporting source summaries
Source 1: case report
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: A female patient whose clozapine levels and clinical status had been stable.
The abstract reports lower clozapine levels and worsened clinical status after St. John's wort, with recovery after withdrawal.
How this applies: Direct named botanical and clozapine case evidence for lower levels and clinical worsening, bounded by missing regimen details.
Single case with abstract-only details; no exact product, dose, level, duration, or washout can be inferred.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed clozapine.
Concomitant use is not recommended. Stopping an inducer can raise clozapine levels and may require prescriber-directed adjustment.
How this applies: Direct exact-medication and named-botanical guidance.
No hour-based separation, fixed washout, or universal botanical dose is given.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Private package prepared without clinical approval or release. | |
| Research summary published |
Article revision: 1f8839a9636b685f
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.