The short answer
Added sedation from St John’s wort with carbinoxamine has not been established. Carbinoxamine itself can make you sleepy, and the herb’s many other medication interactions still justify a full product review.
What this answer covers
Oral carbinoxamine with the specific preparation described below.
- Supplement or preparation
- Hypericum perforatum
- Medication ingredient
- carbinoxamine
Carbinoxamine is a sedating antihistamine
Both immediate-release and extended-release carbinoxamine labeling warn about drowsiness and combinations with sedatives. The extended-release formulation has its own exposure pattern; it should not be used to infer an immediate-release schedule.
The herb’s warning is more specific than a blanket sedative label
St John’s wort guidance describes dizziness, restlessness, trouble sleeping and important interactions with selected medicines. Those facts do not establish that it acts as a clinically significant sedative with carbinoxamine. Reports involving infants exposed through breastfeeding also do not answer this adult combination question.
Keep different interaction mechanisms separate
Carbinoxamine’s warning about MAO inhibitors does not mean every antidepressant herb belongs to that drug class. Likewise, enzyme interactions documented for other medicines cannot substitute for a measured sedation effect from this exact pair.
Review the whole alertness burden
Bring the exact supplement label and all medicines to your pharmacist, particularly if carbinoxamine 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
Added sedation from St John’s wort with carbinoxamine has not been established. Carbinoxamine itself can make you sleepy, and the herb’s many other medication interactions still justify a full product review.
- Exact scope
- Oral carbinoxamine with the specific preparation described below. with Oral carbinoxamine; the hyoscine source, where relevant, is explicitly transdermal.
- Medication form and route
- oral
What remains uncertain
- Adult exact-pair sedation not demonstrated. St John’s wort is not automatically an MAO inhibitor or a proven CNS depressant; infant breastfeeding drowsiness reports are not adult carbinoxamine evidence.
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 carbinoxamine.
Carbinoxamine is a sedating antihistamine with anticholinergic activity. The immediate-release label cautions about sedatives and tranquilizers; MAO inhibitors are separately contraindicated.
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: Current U.S. regulatory product labeling
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed extended-release carbinoxamine maleate.
Warns of marked drowsiness and additional CNS depressant effects; anticholinergic effects matter in gastrointestinal obstruction.
How this applies: Additional exact-ingredient formulation context.
Extended-release exposure is not an immediate-release schedule. No exact botanical event rate.
Source 3: Federal supplement guidance
nccih.nih.gov · Source check Sep 10, 2026
Population: People considering the named botanical or supplement.
St John’s wort has important interactions with certain medicines. Adult adverse effects include dizziness, restlessness and trouble sleeping.
How this applies: Does not establish adult carbinoxamine co-sedation; breastfeeding infant reports cannot be transferred to adult co-use.
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: d4346f42f6110ba9
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.