The short answer
Kava may add to metaxalone-related drowsiness or impairment. The exact combination risk is unmeasured, so have co-use reviewed rather than relying on a timing gap.
What this answer covers
Piper methysticum beverages/extracts; product strengths vary.
- Supplement or preparation
- Piper methysticum
- Medication ingredient
- metaxalone
Why added impairment is plausible
Metaxalone can depress the central nervous system. Supplement guidance cautions about use with other sedating substances.
What the evidence does not show
No inspected trial provides this pair’s added adverse-event rate. A trial finding no sleep or anxiety benefit from kava/valerian does not prove absence of sedation.
Follow the exact medication directions
Metaxalone 640 mg and 800 mg products have different exposure and switching instructions. Do not substitute a product or alter dosing based on this possible interaction.
Review use and avoid impaired activities
Tell the prescriber about the supplement and other sedating medicines. Avoid driving while impaired. No short spacing interval is established protection; severe confusion, difficulty breathing or inability to wake needs urgent help.
Evidence and practical considerations
Side effects & toxicity
Conditional additive-drowsiness precaution from metaxalone label and supplement effects/guidance; no exact pair incidence or formulation-independent dose rule.
- Exact scope
- Piper methysticum beverages/extracts; product strengths vary. with Metaxalone59078 IN; oral640mg/800mg formulation boundaries and non-opioid muscle-relaxant scope.
- 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 metaxalone
CNS depression and serotonin-syndrome precautions with serotonergic drugs; contraindicated with severe renal/hepatic impairment.
How this applies: Exact metaxalone RxCUI 59078 IN, with stated salt/formulation/route bridge.
640mg and 800 mg products are not mutually substitutable mg-for-mg; no supplement-specific incidence.
Source 2: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed metaxalone
Drowsiness/CNS-depressant and serotonin-syndrome warnings; food can affect exposure.
How this applies: Exact metaxalone RxCUI 59078 IN, with stated salt/formulation/route bridge.
Separate formulation instructions; not a pain opioid or evidence that every supplement is contraindicated.
Source 3: federal supplement safety guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: Users of the specified supplement.
Kava should not be used with other sedating substances. Various kava products have been linked to rare liver injury, sometimes serious or fatal.
How this applies: Original source interpreted for metaxalone only within the stated preparation and endpoint limits.
Not a direct metaxalone 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: 391 participants with anxiety and insomnia.
Neither botanical improved its primary anxiety/insomnia outcome over placebo.
How this applies: Original source interpreted for metaxalone only within the stated preparation and endpoint limits.
Not a direct metaxalone 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 |
|---|---|
| Article prepared | |
| Prepared exact metaxalone article with formulation-specific evidence and uncertainty. | |
| Research summary published |
Article revision: 751d76de911fc076
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.