The short answer
Extra sedation from St John’s wort with prochlorperazine has not been established. Prochlorperazine itself can make you drowsy, and there is no validated supplement spacing rule for this pair.
What this answer covers
Oral prochlorperazine with the exact supplement preparation described.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- prochlorperazine
A broad herb-interaction warning is not a sedation result
St John’s wort has important interactions with selected medicines, but its guidance describes effects including dizziness, restlessness and trouble sleeping. That does not make it a proven sedative when combined with prochlorperazine.
The medicine can affect alertness on its own
Prochlorperazine can cause drowsiness, dizziness and low blood pressure. Those known effects remain relevant, but they should not be described as a measured increase caused by this particular herb.
No validated hours-apart rule was found
The inspected sources do not show that separating these products preserves treatment or prevents adverse effects. Starting or stopping a pharmacologically active extract can have a different effect from moving one dose to another time.
Coordinate changes with the prescriber
Discuss the actual extract, dose and reason for use before changing either product. Do not increase or stop prochlorperazine to compensate for a predicted interaction that has not been established for the combination.
Evidence and practical considerations
Side effects & toxicity
Extra sedation from St John’s wort with prochlorperazine has not been established. Prochlorperazine itself can make you drowsy, and there is no validated supplement spacing rule for this pair.
- Exact scope
- Oral prochlorperazine with the exact supplement preparation described. with Oral prochlorperazine with the stated label and formulation limits.
- Medication form and route
- oral
What remains uncertain
- Original exact-pair exposure, toxicity and timing propositions insufficient unless individually specified below. Human CYP3A4 probe induction does not establish the target medicine concentration or clinical response. No protective gap or automatic dose adjustment. Q3 sedation and Q4 timing/avoidance remain insufficient; other-medicine enzyme findings cannot validate them.
Factors that may matter: Exact preparation and amount; Other medicines; Seizure history, alertness or electrolyte status where relevant.
Read the supporting source summaries
Source 1: Current U.S. regulatory product labeling
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral prochlorperazine.
Oral prochlorperazine can cause drowsiness, dizziness, hypotension and anticholinergic effects. Phenothiazine adverse effects include photosensitivity.
How this applies: Exact ingredient and oral-route clinical context.
Label class warnings do not establish every exact botanical interaction, event rate or protective supplement interval.
Source 2: Federal supplement guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the named botanical or supplement.
St John’s wort has important interactions with certain medicines. Adult adverse effects include dizziness, restlessness and trouble sleeping.
How this applies: Selected medicine interactions and supplement adverse effects do not prove every antipsychotic exposure or sedation claim.
General guidance does not quantify this exact medication combination or establish a universal protective interval.
Source 3: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twelve older adults in a supplement and enzyme-probe study.
St John’s wort increased CYP3A4 probe activity, with no significant CYP1A2 or CYP2D6 effect identified for that herb.
How this applies: Mechanistic human context with exact substrate limits.
No target antipsychotic was administered. Results depend on extract and enzyme substrate; CYP3A4 induction does not establish CYP2D6-driven medicine loss of effect.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Initial source-checked draft with exact preparation limits, original study findings and uncertainty. Clinical review not recorded. | |
| Research summary published |
Article revision: d8fb8311ff45c020
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.