Drug & supplement interaction

Green Tea + Metformin, Linagliptin

Metformin, Linagliptin brand name: Jentadueto.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Metformin, Linagliptin falls into 3 drug categories that Green Tea can interact with; the most serious is rated moderate. Green tea might increase the levels and adverse effects of P-glycoprotein (P-gp) substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Green Tea and Metformin, Linagliptin

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Green Tea interacts with whole categories of medication. Metformin, Linagliptin falls into 3 of those categories, so it can interact with Green Tea in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

P-GLYCOPROTEIN SUBSTRATES

1 of 3

Why this applies to Metformin, Linagliptin

Metformin, Linagliptin falls under P-GLYCOPROTEIN SUBSTRATES — the group Green Tea interacts with.

Green tea might increase the levels and adverse effects of P-glycoprotein (P-gp) substrates.
In vitro research and case reports suggest that green tea inhibits drug efflux by P-gp, potentially increasing serum levels of P-gp substrates. Case reports from the World Health Organization (WHO) adverse drug reaction database describe increased toxicity in patients taking green tea and certain P-gp substrates.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with Jentadueto (which combines metformin and linagliptin). Green tea may block a transporter in your body called P-glycoprotein, which helps move certain drugs around and out of your system. Linagliptin in particular relies partly on this pump, so in theory green tea could let a little more of it linger in your blood. That could mean a slightly stronger effect, with possible low blood sugar (shakiness, sweating, dizziness) or stomach upset like nausea.

I want to be honest about how shaky this evidence is. It comes mostly from lab studies and a handful of case reports, not solid trials. A cup or two of green tea a day is very unlikely to cause trouble. Concentrated green tea extract pills are the bigger question mark. If you take those regularly, check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pochet S, Lechon AS, Lescrainier C, et al. Herb-anticancer drug interactions in real life based on VigiBase, the WHO global database. Sci Rep 2022;12(1):14178. PubMed
Minor

ANTIDIABETES DRUGS

2 of 3

Metformin, Linagliptin also falls under ANTIDIABETES DRUGS.

Theoretically, taking green tea with antidiabetes drugs might interfere with blood glucose control.
Concomitant use of green tea and antidiabetes drugs might interfere with blood glucose control. The data are conflicting. Reports claim that green tea and/or caffeine, a constituent of green tea, might increase or decrease blood sugar.
Severity Minor Likelihood Unlikely Evidence B

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Good question about pairing green tea with Jentadueto (the metformin and linagliptin combo you take for blood sugar). Honestly, this one is pretty low on my worry list. The concern here is only theoretical, and the studies we have actually pull in both directions: green tea and its caffeine might nudge blood sugar up a little in some people and down a little in others. There's no strong evidence it reliably throws off your control either way.

For most folks, a normal cup or two a day shouldn't cause trouble. The bigger thing to watch is concentrated green tea extract supplements, which can rarely stress the liver. If you notice unusual highs or lows in your readings after adding green tea, just mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Watson JM, Jenkins EJ, Hamilton P, et al. Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes. Diabetes Care 2000;23:455-9. PubMed
  2. Bell DG, Jacobs I, Ellerington K. Effect of caffeine and ephedrine ingestion on anaerobic exercise performance. Med Sci Sports Exerc 2001;33:1399-403. PubMed
  3. Josic, J., Olsson, A. T., Wickeberg, J., Lindstedt, S., and Hlebowicz, J. Does green tea affect postprandial glucose, insulin and satiety in healthy subjects: a randomized controlled trial. Nutr.J. 2010;9:63. PubMed
  4. Hsu, C. H., Liao, Y. L., Lin, S. C., Tsai, T. H., Huang, C. J., and Chou, P. Does supplementation with green tea extract improve insulin resistance in obese type 2 diabetics? A randomized, double-blind, and placebo-controlled clinical trial. Altern.Med.R
  5. Bogdanski, P., Suliburska, J., Szulinska, M., Stepien, M., Pupek-Musialik, D., and Jablecka, A. Green tea extract reduces blood pressure, inflammatory biomarkers, and oxidative stress and improves parameters associated with insulin resistance in obese, h
  6. Liu K, Zhou R, Wang B, Chen K, Shi LY, Zhu JD, Mi MT. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. Am J Clin Nutr. 2013 Aug;98(2):340-8. PubMed
Minor

METFORMIN (Glucophage)

3 of 3
Theoretically, metformin might increase the levels and adverse effects of caffeine.
Green tea contains caffeine. Animal research suggests that metformin can reduce caffeine metabolism. Theoretically, concomitant use can increase caffeine serum concentrations and the risk of caffeine adverse effects.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's a twist on how this one works: it's not your Jentadueto (metformin/linagliptin) that builds up, it's the caffeine in green tea. Animal studies hint that the metformin part may slow down how your body clears caffeine, so the caffeine could hang around a bit longer than usual. That might mean more jitteriness, a racing heart, trouble sleeping, or an upset stomach, basically caffeine side effects turned up a notch.

I want to keep this in perspective. This is a theoretical concern based only on lab and animal data, and it's rated minor. A normal cup or two of green tea is very unlikely to cause trouble. If you load up on concentrated green tea extracts or drink a lot of caffeine and feel wired, mention it to your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Mohiuddin, M., Azam, A. T., Amran, M. S., and Hossain, M. A. In vive effects of gliclazide and metformin on the plasma concentration of caffeine in healthy rats. Pak.J Biol Sci 5-1-2009;12(9):734-737.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Green Tea Also Interacts With Other Medications

Green Tea has 13 major, 904 moderate, 375 minor known drug interactions in our database — the Metformin, Linagliptin one above is among them. If you take anything else, check it against the full list below.

Major 13 Moderate 904 Minor 375 No known interaction 1,538 (incl. Metformin, Linagliptin)
Taking anything else?

Check Another of Your Medications Against Green Tea

Covers the 2,830 medications we’ve checked against Green Tea. Pick one to open its full report.

From our Q&A

Questions About Green Tea or Metformin, Linagliptin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Green Tea or Metformin, Linagliptin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Metformin, Linagliptin

This page covers Green Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin, Linagliptin page lists 285 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), St. John's Wort (major), Acai (moderate) and Adrafinil (moderate).

By severity: 3 major · 242 moderate · 40 minor.

From our pharmacist’s overview on the Metformin, Linagliptin page

“Siberian cocklebur is the risk anyone taking metformin and linagliptin (Jentadueto) should understand first, since it has caused severe hypoglycemia in people who consumed it. The wider picture deserves real care too.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin, Linagliptin interaction page

One more smart check

Taking Green Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9,084 real supplement products containing Green Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Green Tea. Your product may carry other ingredients that interact with Metformin, Linagliptin too, on top of Green Tea — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Green Tea and Metformin, Linagliptin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Green Tea
Top 5%

#25 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Metformin, Linagliptin
Steady interest

#1,557 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Green Tea

What is Green Tea?

Green Tea
  • Antioxidant support
  • Weight loss
  • Heart health
  • Mental alertness
  • Cancer risk reduction

Green tea is a popular beverage rich in antioxidants called catechins, and drinking it in normal amounts is considered safe for most people. Concentrated green tea extracts are a different story—they may help modestly with weight or heart health for some, but high doses have been linked to rare liver problems. Talk to your pharmacist or doctor before taking green tea supplements, especially if you have liver concerns or are pregnant.

Read the full Green Tea monograph & all interactions
Keep checking

Other Drugs & Green Tea

Browse every other medication we’ve checked against Green Tea — both the ones with a known interaction and the ones without. Select any drug for the full detail.

13Major
904Moderate
375Minor
1,537No known interaction
13 Major 904 Moderate 375 Minor 1,537 No interaction
Major

13 interactions

Moderate

904 interactions

Showing 60 of 904 moderate interactions — see all 904 on the Green Tea page.

Minor

375 interactions

Showing 60 of 375 minor interactions — see all 375 on the Green Tea page.

No interaction 1,537 drugs checked — show the list

We also checked Green Tea against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,537 medications checked with no known interaction — see the full Green Tea list.

See the full Green Tea interactions page
See every supplement checked against Metformin, Linagliptin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Green Tea monograph › Uses, safety, and every drug interaction in one place Metformin, Linagliptin supplement interactions › Every supplement checked against Metformin, Linagliptin, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Green Tea and Metformin, Linagliptin Together: Common Questions

Can you take Green Tea with Metformin, Linagliptin?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Green Tea and Metformin, Linagliptin?
Metformin, Linagliptin belongs to more than one drug category, and Green Tea interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Green Tea and Metformin, Linagliptin interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Metformin, Linagliptin and Green Tea?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.