The short answer
Green tea and certain concentrated leaf extracts can reduce the amount of nadolol absorbed. Review them with your prescriber, and do not assume that taking nadolol one hour later avoids the interaction.
What this answer covers
Oral nadolol with the exact supplement preparation described below. Studied green-tea brews and aqueous EGCG-concentrated leaf extracts, not automatic equivalence with black tea or every capsule.
- Supplement or preparation
- Camellia Sinensis Leaf Extract
- Medication ingredient
- nadolol
Human studies found reduced nadolol exposure
A repeated green-tea study substantially lowered nadolol levels and reduced its systolic-pressure effect. Kidney clearance did not change, making reduced intestinal availability the main concern.
A one-hour gap did not solve the problem
Another crossover study found lower nadolol exposure both with tea and when tea was consumed one hour earlier. It did not establish a longer interval that reliably prevents the interaction.
Extract evidence is preparation-specific
A separate human study tested aqueous green-tea extracts concentrated in EGCG and also found lower nadolol exposure. Short-term pulse and pressure differences were not significant. These results cannot establish the effect size of every tea or supplement.
Discuss changes before adjusting treatment
Bring the tea or extract label to your prescriber. Do not increase nadolol to compensate or switch tea intake unpredictably. A plan should account for the product and the condition being treated.
Evidence and practical considerations
Absorption & effectiveness
Green tea and certain concentrated leaf extracts can reduce the amount of nadolol absorbed. Review them with your prescriber, and do not assume that taking nadolol one hour later avoids the interaction.
- Exact scope
- Oral nadolol with the exact supplement preparation described below. Studied green-tea brews and aqueous EGCG-concentrated leaf extracts, not automatic equivalence with black tea or every capsule. with Oral nadolol; intravenous cases are identified as indirect route evidence where discussed.
- Medication form and route
- oral
What remains uncertain
- Direct human beverage and aqueous EGCG-extract studies support reduced exposure. One-hour separation failed; short studies do not quantify long-term outcomes for all teas or capsules.
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 nadolol.
Nadolol is not metabolized by the liver and is mainly cleared unchanged by the kidneys. Kidney function affects dosing. Bradycardia and abrupt-withdrawal precautions apply.
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: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Ten healthy volunteers.
Green tea substantially reduced nadolol exposure and its systolic-pressure effect without changing renal clearance.
How this applies: Direct evidence of reduced oral nadolol availability with the studied tea.
Small selected beverage study; not every tea, route or long-term disease outcome.
Source 3: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Eleven healthy volunteers completing a crossover study.
Exposure fell with concurrent tea and with tea one hour beforehand. Acute pulse/pressure comparisons did not significantly differ.
How this applies: Supports a preparation-specific avoidance/review approach, without inventing a two-hour guarantee.
One-hour separation failed; a longer protective interval was not established. Concentrated brew and healthy volunteers limit generalization. Full indexed original read despite raw PMC challenge/API404.
Source 4: Original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Thirteen healthy volunteers.
Both extracts reduced nadolol exposure; pulse and pressure did not significantly change in the short experiment.
How this applies: Direct human extract evidence, stronger than inference from rat experiments alone.
Specific aqueous preparations; no risk estimate for every capsule, black tea, duration or disease.
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: 8416207f59d6dfb0
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.