The short answer
Review kava with the prescriber before adding it to mirtazapine. Kava guidance cautions against combining it with sedating substances.
What this answer covers
Oral Piper methysticum; extract, amount and other sedatives are relevant.
- Supplement or preparation
- Piper methysticum
- Medication ingredient
- mirtazapine
Why the precaution is relevant
NCCIH advises against kava with sedative substances. Mirtazapine can affect alertness, so review the actual product and other sedating medicines before adding it.
A reassuring study has limits
A small study did not find impaired driving from its kava preparation compared with placebo. Oxazepam was a separate comparator, and the treatments were not combined.
Check the complete extract label
Different kava extracts and blends need separate assessment. A few hours between doses has not been shown to prevent combined impairment.
Watch for impaired alertness
Mirtazapine can affect alertness and coordination. Avoid driving if affected and contact the prescriber if added sleepiness, confusion or unsteadiness appears after a new product. Severe confusion, fainting or inability to wake needs urgent assessment.
Evidence and practical considerations
Side effects & toxicity
Conditional alertness review is supported by product guidance and medication effects; exact pair-specific risk is unmeasured.
- Exact scope
- Oral Piper methysticum; extract, amount and other sedatives are relevant. 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
- A separate-dose driving study with oxazepam does not test this antidepressant combination. No protective spacing interval.
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: official guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the specified supplement.
Advises against use with sedative substances. Kava may cause dizziness and has been linked to rare severe liver injury, including with different extraction methods.
How this applies: Preparation-specific original evidence; no untested antidepressant or route transfer.
Not a mirtazapine study. Intrinsic liver risk does not establish added mirtazapine hepatotoxicity; preparation and co-exposure vary.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Twenty-two adults in a randomized crossover driving study.
Medicinal-dose kava did not significantly impair driving outcomes; oxazepam impaired some outcomes.
How this applies: Preparation-specific original evidence; no untested antidepressant or route transfer.
Not combined administration or evidence that all kava preparations lack impairment.
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: ed47eb3885111f79
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.