The short answer
Mirtazapine explicitly warns about St John’s wort and serotonin syndrome. Review any addition or withdrawal with the prescriber; a dose gap is not established protection.
What this answer covers
Oral Hypericum perforatum; extract composition and hyperforin content matter.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- mirtazapine
The serotonin warning names this herb
Mirtazapine information specifically lists St John’s wort among serotonergic products of concern. This supports reviewing co-use even without a measured exact-pair event rate.
Metabolism and serotonin are separate issues
The medicine label describes effects of strong CYP3A modifiers. St John’s wort studies using alprazolam show that one extract reduced exposure while a low-hyperforin extract had no relevant effect. These were not mirtazapine trials.
A universal dose change does not follow
Do not increase mirtazapine or rely on spacing based on another drug’s result. Bring the actual extract and recent changes to the prescriber.
Recognize concerning symptoms
Seek urgent medical care for a combination of agitation or confusion, fever or heavy sweating, tremor, muscle rigidity or repeated twitching. These can be signs of serotonin syndrome; a single nonspecific symptom does not establish the diagnosis.
Evidence and practical considerations
Side effects & toxicity
Conditional serotonin review is directly supported by the medicine label. Exact reduced-effectiveness or absorption claim lacks a mirtazapine co-use study.
- Exact scope
- Oral Hypericum perforatum; extract composition and hyperforin content matter. with Exact oral mirtazapine tablets and orally disintegrating tablets. Exact oral mirtazapine in Remeron and RemeronSolTab; manufacturer label covers both. No equivalence to unrelated mirtazapine salts or other antidepressants inferred.
- Medication form and route
- oral
- Timing or duration
- Source-specific single-dose, repeated-dose and observational exposures distinguished.
What remains uncertain
- Other-drug CYP probe studies differ by extract and do not quantify mirtazapine exposure or intestinal absorption.
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 oral mirtazapine.
Exact label names tryptophan and St John’s wort in serotonin warnings; CYP3A induction/inhibition may affect levels. Drowsiness and cognitive/motor impairment occur.
How this applies: Exact oral mirtazapine in Remeron and RemeronSolTab; manufacturer label covers both. No equivalence to unrelated mirtazapine salts or other antidepressants inferred.
No universal supplement interval, event rate or preparation equivalence established. Original label distinguishes warnings from measured pair-specific results.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twelve healthy volunteers in an open-label fixed-order crossover.
Alprazolam exposure fell about one-half and clearance increased; elimination half-life shortened.
How this applies: Preparation-specific original evidence; no untested antidepressant or route transfer.
Single extract and short exposure, healthy volunteers; no anxiety-treatment failure endpoint. Does not imply reduced gut absorption or transfer to predominantly conjugated benzodiazepines.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Healthy participants in randomized placebo-controlled studies.
Changes in probe exposures were small and judged clinically irrelevant; hyperforin levels were below quantification.
How this applies: Preparation-specific original evidence; no untested antidepressant or route transfer.
Preparation-specific result, not permission to assume all retail products are low-hyperforin or all doses safe.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Current exact available claims adjudicated using original captures and explicit identity and comparator limits. | |
| Research summary published |
Article revision: e37a25abbf348ccb
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.
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Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.