Guide
Green tea extract and medications: what to check
Green tea catechins have been shown to reduce how much of several prescription medications the body absorbs, sometimes substantially, and green tea is separately flagged as a substance to watch for bleeding risk with warfarin. Caffeine content adds a further, separate consideration.
Green tea catechins have been shown to reduce how much of several prescription medications the body actually absorbs — sometimes by a large amount — and green tea is separately named as a substance to watch for bleeding risk alongside warfarin. Caffeine content, which varies by product, adds a further, separate consideration for anyone taking a stimulant medication or managing their own caffeine intake.
Medications whose absorption changes
A 2025 clinical pharmacology review pulled together the published human studies testing how green tea catechins affect the pharmacokinetics — the absorption and blood levels — of specific prescription medications. Across the pharmacokinetic analyses reviewed, most (72%) found green tea catechins significantly reduced systemic exposure to the medication tested, by anywhere from 18% to 99%, mainly by blocking an intestinal transport protein (OATP1A2) that helps some drugs get absorbed, or by reducing drug solubility. Medications affected this way included the statins atorvastatin and rosuvastatin, the blood pressure medications lisinopril, nadolol, and celiprolol, the heart medication digoxin, the allergy medication fexofenadine, folic acid, and the cancer medications nintedanib and raloxifene. One analysis found the opposite direction: green tea catechins increased exposure to sildenafil by about 50%. For several other medications tested — the statins fluvastatin and simvastatin, the decongestant pseudoephedrine, and the cancer medication tamoxifen — no significant change in absorption was found. Case reports specifically linked a change in drug levels from green tea consumption to a change in how well the medication worked for two of these: nadolol and erlotinib (PMID 39748104).
The practical takeaway isn't "avoid all medications" — it's that the effect is medication-specific and can't be assumed either way. If you take any of the specific medications above, or a similar one in the same drug class, ask a doctor or pharmacist whether the timing or dose needs adjusting before adding green tea extract.
Statins specifically
Since statins showed up on both sides of the 2025 review above — reduced absorption for atorvastatin and rosuvastatin, no change for fluvastatin and simvastatin — a blanket statement about "green tea and statins" isn't accurate. Ask a pharmacist which category your specific statin falls into before combining it with green tea extract.
Blood thinners and bleeding risk
A 2021 systematic review of 149 published reports on warfarin interactions with food, herbs, and dietary supplements classified 78 substances by how they affected warfarin, and named green tea among the substances associated with an increased bleeding risk when combined with warfarin (PMID 32478963). No dedicated trial we reviewed tested green tea extract against a newer anticoagulant specifically. Ask a doctor before combining green tea extract with warfarin or any other blood thinner.
Caffeine stacking
Unless labeled decaffeinated, green tea extract likely carries some of the leaf's natural caffeine, and the exact amount varies a lot by product — a 2007 USDA lab analysis of caffeine-containing supplements found per-day amounts ranging from 1 mg to 829 mg across the products tested (PMID 17676317). Combining it with coffee, energy drinks, or a stimulant medication adds up whatever caffeine content each source carries; ask a doctor if you take a stimulant medication and are considering adding a caffeinated supplement on top of it.
Medications with no dedicated interaction data
No dedicated trial we reviewed tested green tea extract combined with an SSRI (such as sertraline), an antidepressant more broadly (such as bupropion), or metformin. That's an absence of evidence, not evidence of safety — ask a doctor or pharmacist before combining green tea extract with any prescription medication not specifically covered above, including these.
Questions people ask
Does green tea extract interact with blood thinners?
Green tea is named in a systematic review of warfarin interactions as a substance associated with increased bleeding risk. Ask a doctor before combining it with warfarin or another blood thinner.
Can you take green tea extract with a statin?
It depends on the specific statin. Reduced absorption has been shown for atorvastatin and rosuvastatin; no significant change was found for fluvastatin and simvastatin. Ask a pharmacist which applies to your prescription.
Does green tea extract interact with metformin?
No dedicated trial we reviewed tested this combination. Ask a doctor or pharmacist before combining them.
Does green tea extract interact with blood pressure medication?
Yes, for some specific medications — lisinopril, nadolol, and celiprolol all showed reduced absorption when combined with green tea catechins in the studies reviewed, and case reports linked reduced nadolol levels to reduced blood-pressure control in at least one instance. Ask a doctor if you take a blood pressure medication.
Can you take green tea extract with an antidepressant?
No dedicated trial we reviewed tested green tea extract combined with an SSRI or another antidepressant. Ask a doctor or pharmacist before combining them.
Does green tea extract interact with coffee?
No dedicated trial tested this combination specifically, but both can contain caffeine, so combining them adds up whatever caffeine content each one carries.
Related reading: green tea extract side effects, who should not take green tea extract?, and how much green tea extract should you take a day?
Sources
- Green Tea Catechins as Perpetrators of Drug Pharmacokinetic Interactions A 2025 review found green tea catechins reduced the body's absorption of folic acid by a meaningful amount in a pharmacokinetic study — relevant because folate status is specifically important during pregnancy.
- Warfarin and food, herbal or dietary supplement interactions: A systematic review A 2021 systematic review of warfarin interactions named green tea among the substances associated with an increased bleeding risk when combined with warfarin, out of 78 foods, herbs, and supplements reviewed.
- The caffeine contents of dietary supplements commonly purchased in the US: analysis of 53 products with caffeine-containing ingredients A 2007 USDA lab analysis of 53 caffeine-containing dietary supplements — including some with green tea extract — found per-day caffeine content ranging from 1 to 829 mg across products, illustrating how much caffeine content can vary by brand and formulation.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.