The short answer
Guarana adds caffeine, which can affect blood pressure and sleep. An additional stimulant interaction specifically caused by labetalol has not been established, so review the total caffeine and exact seed product.
What this answer covers
Oral labetalol with the exact supplement preparation described below.
- Supplement or preparation
- Paullinia cupana
- Medication ingredient
- labetalol
Guarana is a caffeine-containing ingredient
The seed preparation has stimulant properties and cardiovascular and sleep precautions. A herbal label does not mean the product is caffeine-free.
Intrinsic caffeine effects are not an exact drug interaction
A caffeine study found an acute pressure increase in susceptible participants. It did not test guarana with labetalol or show that labetalol raises guarana exposure.
Review the full energy-product formula
The seed, concentrated extract and multi-ingredient drink may deliver different exposures. Check added caffeine and other stimulants, and do not assume an hours-apart schedule removes their effects.
Keep the prescribed treatment plan
Do not stop labetalol abruptly or adjust the dose to compensate for a supplement. Bring the product label and your recent blood-pressure and pulse readings to your pharmacist or prescriber so any change can be assessed in context.
Evidence and practical considerations
Side effects & toxicity
Guarana adds caffeine, which can affect blood pressure and sleep. An additional stimulant interaction specifically caused by labetalol has not been established, so review the total caffeine and exact seed product.
- Exact scope
- Oral labetalol with the exact supplement preparation described below. with Oral labetalol; intravenous cases are identified as indirect route evidence where discussed.
- Medication form and route
- oral
What remains uncertain
- Guarana caffeine content and intrinsic pressor guidance support narrower product review; no demonstrated labetalol-caused stimulant amplification or fixed safe interval.
Factors that may matter: Exact ingredient and preparation; Kidney function and clinical indication; Concomitant medicines.
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 labetalol.
Oral labetalol undergoes extensive first-pass metabolism, mainly glucuronide conjugation. Food increases bioavailability. This is separate from intravenous exposure and emergency treatment.
How this applies: Exact active-ingredient and oral-route context.
Label omission of an herb does not prove safety. No invented exact supplement interaction rate or universal spacing rule.
Source 2: Regulatory herbal monograph
ema.europa.eu · Source check Sep 10, 2026
Population: Adults considering defined guarana-seed preparations.
Covered seed products have cardiovascular and sleep precautions.
How this applies: Supports stimulant-product review without claiming labetalol raises guarana levels.
Not an exact labetalol co-use trial or every extract. Caffeine content varies; no additional interaction rate established.
Source 3: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Forty-eight young men, half with borderline hypertension.
Caffeine raised pressure more in the borderline-hypertension group.
How this applies: Supports reviewing stimulant intake when assessing blood pressure.
No labetalol co-use, short-term exposure and selected population; not impaired drug absorption.
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: 0be44125f1e17074
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.