The short answer
Confirm which valerian species and preparation you have before combining it with promethazine. A sedating valerian product may add impairment, but the generic root name does not establish a predictable interaction.
What this answer covers
Oral promethazine with the specific preparation described below.
- Supplement or preparation
- Radix et Rhizoma Valerianae
- Medication ingredient
- promethazine
The root name leaves an identity question
Radix et Rhizoma Valerianae describes valerian root and rhizome without resolving the species or extract. Guidance about Valeriana officinalis cannot automatically be applied to every material sold under a generic valerian name.
Why alertness deserves review
Federal guidance describes a possible but unproven sleep-inducing effect and advises against valerian with sedatives. Promethazine can impair mental or physical performance. If the product is a sedating preparation, overlapping effects are a reasonable concern even though this exact combination has not been measured.
Evidence uncertainty changes the strength of the claim
The sources do not establish how often this unspecified root product adds drowsiness, or show a pair-specific respiratory-depression risk. They also do not establish a dose that is safe across species, extracts and other medicines.
Review the whole alertness burden
Bring the exact supplement label and all medicines to your pharmacist, particularly if promethazine already makes you sleepy, dizzy or confused. Avoid driving when affected. The reviewed evidence does not identify a supplement dose or hours-apart schedule that guarantees normal alertness.
Evidence and practical considerations
Side effects & toxicity
Confirm which valerian species and preparation you have before combining it with promethazine. A sedating valerian product may add impairment, but the generic root name does not establish a predictable interaction.
- Exact scope
- Oral promethazine with the specific preparation described below. with Oral promethazine; the hyoscine source, where relevant, is explicitly transdermal.
- Medication form and route
- oral
What remains uncertain
- Inventory root/rhizome name does not authenticate Valeriana officinalis. Conditional alertness guidance for a confirmed sedating preparation, not exact unknown-root evidence, a measured event rate or protective gap.
Factors that may matter: Exact preparation and amount; Other medicines with overlapping effects; Route and gut-transit 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 promethazine.
Promethazine can cause marked drowsiness, can intensify other CNS depressants and requires caution with other anticholinergic medicines. It can lower the seizure threshold.
How this applies: Exact active ingredient and oral-route context.
Label warnings do not measure every exact supplement pair or provide a universal safe supplement dose or interval.
Source 2: Federal supplement guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the named botanical or supplement.
Sedation is possible but not proven; guidance advises avoiding use with sedatives. The material discussed is Valeriana officinalis.
How this applies: The generic root/rhizome inventory name does not prove species identity, so any application is conditional.
General guidance does not quantify this exact medication combination or establish a universal protective interval.
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 research draft with exact preparation limits, contrary findings and source-access details. Clinical review not recorded. | |
| Research summary published |
Article revision: f6ac4d07570936e6
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.