The short answer
Review passionflower before adding it to phenobarbital. It may impair alertness, but the exact combination’s sedation risk has not been established.
What this answer covers
Oral Passiflora incarnata aerial-part preparations matching the monograph; other species or extracts may differ.
- Supplement or preparation
- Passiflora incarnata
- Medication ingredient
- phenobarbital
What official guidance says
The passionflower monograph describes traditional sleep-aid use and possible driving impairment. It also lists no reported interactions. These statements support review but do not prove a phenobarbital interaction.
Human findings are limited
Two short studies around surgery did not find greater sedation or psychomotor impairment with their passionflower products. Neither tested routine use with phenobarbital.
Confirm the actual preparation
Check the Latin species, plant part, extract and added ingredients. No dose interval has been shown to protect against possible combined impairment.
Watch for impaired alertness
Phenobarbital can cause drowsiness and impaired coordination. Avoid driving when affected, and seek urgent help for severe difficulty waking or breathing. Other sedating medicines and alcohol make a careful medication review especially important.
Evidence and practical considerations
Side effects & toxicity
Conditional caution is reasonable; exact-pair additive sedation remains insufficiently established.
- Exact scope
- Oral Passiflora incarnata aerial-part preparations matching the monograph; other species or extracts may differ. with Exact oral phenobarbital; parent and metabolites distinguished; no other drug/route assumed equivalent.
- Medication form and route
- oral supplement unless pregnancy section explicitly distinguishes neonatal injection
- Timing or duration
- Preparation, dose and duration determine applicability; chronic nutrition evidence is not a single-dose interaction.
What remains uncertain
- No phenobarbital co-use trial found. Monograph reports no known interactions, and short preoperative studies found no added sedation; those observations do not prove chronic combination safety.
Factors that may matter: exact supplement identity; dose; other medicines; clinical indication; baseline nutrition; pregnancy where relevant.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral phenobarbital.
Causes CNS depression and can impair driving; other CNS depressants can add to these effects. Adult plasma half-life is prolonged. Abrupt withdrawal after dependence can cause seizures and other serious symptoms. Long-term treatment warrants periodic clinical and laboratory assessment.
How this applies: Exact RxCUI 8134 IN and UNII YQE403BP4D, oral plain ingredient; no automatic sodium-injection or other barbiturate transfer.
Does not name the requested botanicals or establish supplement-specific interaction rates or spacing. Current DailyMed listing is unapproved drug other, not evidence of FDA approval.
Source 2: official guidance
ema.europa.eu · Source check Sep 10, 2026
Population: People considering the specified supplement.
Traditional sleep-aid use; may impair driving. Section 4.5 lists no reported interactions.
How this applies: Preparation-specific context; not a directly measured either requested antiseizure drug interaction.
Traditional-use monograph, not a either requested antiseizure drug trial. No reported interaction is not proof of safety.
Source 3: randomized placebo-controlled trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 60 adults undergoing ambulatory surgery.
Anxiety decreased, but sedation and psychomotor recovery were similar between groups.
How this applies: Preparation-specific context; not a directly measured either requested antiseizure drug interaction.
Short perioperative exposure to one product, no either requested antiseizure drug; does not establish chronic combination safety.
Source 4: randomized placebo-controlled trial
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 60 adults aged 25-55 undergoing spinal anesthesia.
No significant group differences in sedation, psychomotor function, hemodynamics or side effects.
How this applies: Preparation-specific context; not a directly measured either requested antiseizure drug interaction.
Selected perioperative population, no either requested antiseizure drug; not proof that all 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 | |
| Exact current available claims reviewed against captured originals; no clinical review asserted. | |
| Research summary published |
Article revision: c4ccdcae6c8b24fd
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.