Herb & supplement monograph

Theaflavin Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by ·Updated June 2026
What is this page for?

First and foremost: how Theaflavin interacts with medications. The heart of this page is the interaction list — every drug Theaflavin is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Theaflavin is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Reviewed by licensed pharmacists Sourced from Natural Medicines
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Interaction report

Drugs that interact with Theaflavin

130 medications have a known interaction with Theaflavin, graded by severity. Select any drug for the full evidence-based detail.

2,830 drugs
AcarboseGlucobay, Prandase, Precose› AcetohexamideDymelor› AlbiglutideTanzeum› AlogliptinNesina› Alogliptin, MetforminKazano› Alogliptin, PioglitazoneOseni› Antidiabetes, Dipeptidyl Peptidase-4 (dpp-iv) InhibitorGlyxambi› AtorvastatinAtorvaliq› Atorvastatin CalciumLipitor› BosentanTracleer› BrincidofovirTembexa› CanagliflozinInvokana› Canagliflozin, MetforminInvokamet› Canagliflozin, Metformin HydrochlorideInvokamet XR› CeliprololCelicard› Cerivastatin SodiumBaycol› ChlorpropamideChlorpropam, Diabinese› CinoxacinCinobac› CiprofloxacinCiloxan, Cipro, Cipro IV, Cipro XR, Ciprobay, Otiprio› Ciprofloxacin, HydrocortisoneCipro HC Otic› ClinafloxacinClinafloxacin› DapagliflozinFarxiga› Dapagliflozin Propanediol, MetforminXigduo XR› Dapagliflozin Propanediol, Saxagliptin HydrochlorideQtern› Dapagliflozin, Metformin Hydrochloride, Saxagliptin HydrochlorideQternmet XR› Dasiglucagon HydrochlorideZegalogue› DulaglutideTrulicity› EmpagliflozinJardiance› Empagliflozin, Linagliptin, Metformin HydrochlorideTrijardy XR› Empagliflozin, MetforminSynjardy›
Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. Interaction 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each drug listed above links to the full report for that exact Theaflavin combination — clinical detail, likelihood, evidence level, and citations.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.
The big picture

The kinds of drugs Theaflavin affects

Every type of medication (drug category) Theaflavin is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 2 drug categories Theaflavin interacts with
Antidiabetes DrugsOrganic Anion-transporting Polypeptide Substrates (oatp)
Antidiabetes Drugs

In an animal diabetic model, giving theaflavin reduced fasting blood glucose, with an effect comparable to metformin. A fermented green tea product containing theaflavin also appears to reduce blood glucose levels in healthy humans and in an animal model. Theoretically, concomitant use with antidiabetes drugs might cause additive hypoglycemic effects. Use with caution.

Likelihood Possible Evidence D
Organic Anion-Transporting Polypeptide Substrates (Oatp)

In vitro, theaflavin inhibits organic anion-transporting polypeptide (OATP)2B1. OATP2B1 is expressed in the small intestine and liver and is responsible for the uptake of drugs and other compounds. This interaction has not been shown in humans. However, theaflavin might reduce the absorption of drugs that are OATP2B1 substrates. Use with caution.

Likelihood Possible Evidence D
Monograph

Theaflavin: Uses, Safety & Side Effects

Medically reviewed by · Reviewed June 2026 ·
The bottom line

Theaflavins are antioxidant compounds formed when tea leaves are oxidized to make black tea. Early research suggests they may help with cholesterol and provide antioxidant effects, but high-quality human evidence is limited and doses are not standardized. Drinking black tea is generally safe, but talk to your pharmacist or doctor before taking concentrated extracts.

Scientific name
Camellia sinensis
Family
Theaceae
Part used
Leaves (fermented/oxidized, as in black tea)
Common forms
Black tea, standardized black tea extract capsules, tablets, powders
People commonly use it for
  • Heart health and cholesterol support
  • Antioxidant support
  • Weight management
  • Blood sugar support
  • General wellness

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance
OverallUse caution

Black tea is generally safe in normal amounts, but concentrated extracts are less studied.

PregnancyInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full pregnancy detail
BreastfeedingInsufficient reliable information

Insufficient reliable information available; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Theaflavins are a group of plant compounds (polyphenols) found mainly in black tea. They are created when the leaves of the tea plant, Camellia sinensis, are oxidized (sometimes called fermented) during black tea processing. This same process gives black tea its dark color and rich flavor.

The tea plant is grown widely in countries such as China, India, Sri Lanka, and Kenya. While green tea is best known for a compound called EGCG, theaflavins are more specific to black tea. Some people drink black tea for these compounds, while others take black tea extract supplements standardized to contain theaflavins.

How it works

Theaflavins act as antioxidants, meaning they may help neutralize unstable molecules called free radicals that can damage cells. This antioxidant activity is the main reason researchers are interested in them.

In laboratory and animal research, theaflavins have shown effects such as reducing inflammation and possibly affecting how the body absorbs and handles cholesterol and fats. Some studies also explore effects on blood vessels and blood sugar.

It is important to remember that much of this is based on test-tube and animal studies. What happens in a lab does not always translate into meaningful health benefits in people.

Effectiveness

Does Theaflavin work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by .

Evidence overview · 1 use evaluated
1 Insufficient evidence
How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.
2Likely EffectiveGood evidence, though not yet conclusive.
3Possibly EffectiveSome evidence suggests a benefit.
4Possibly IneffectiveSome evidence it may not help.
5Likely IneffectiveFairly strong evidence it doesn’t help.
6IneffectiveStrong evidence it doesn’t work.
7Insufficient Reliable Evidence to RateToo little research to say either way.

For Theaflavin, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 1 condition — evidence insufficient to rate
Insufficient Reliable Evidence To Rate Hyperlipidemia
Rating & evidence shown verbatim from Natural Medicines

Preliminary clinical research in Chinese adults with mild to moderate untreated hyperlipidemia shows that taking a theaflavin-enriched green tea extract providing 75 mg of theaflavin daily for 12 weeks reduces total cholesterol by 11% and low-density lipoprotein (LDL) cholesterol by 16% when compared with placebo.

Sources Ref 11308

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

Drinking black tea in normal amounts is generally considered safe for most adults. Concentrated theaflavin or black tea extract supplements are less studied, so their long-term safety is not well understood.

Because black tea naturally contains caffeine, people sensitive to caffeine, those with heart rhythm problems, anxiety, or sleep trouble should be cautious. Some concentrated extracts may also affect the stomach or, rarely, the liver. People with liver conditions should be especially careful with high-dose tea extracts.

For pregnancy and breastfeeding, it is safest to limit caffeine-containing tea and to avoid concentrated extracts unless your doctor approves, since safety data for supplements is lacking. Always check with your pharmacist or doctor before starting any new supplement.

Side effects

When consumed as black tea, theaflavins rarely cause problems beyond the effects of caffeine, such as jitteriness, trouble sleeping, a fast heartbeat, or an upset stomach. Drinking tea on an empty stomach can cause nausea in some people.

Concentrated extracts may more commonly cause stomach upset. In rare cases, high doses of tea extracts have been linked to liver problems. Stop use and seek medical care if you notice symptoms such as yellowing of the skin or eyes, dark urine, severe stomach pain, or unusual fatigue.

Dosing

There is no established standard dose of theaflavin. Supplements vary widely in how much theaflavin they contain and how the black tea extract is standardized.

If you choose to take a product, follow the directions on the label and do not exceed the recommended amount. Because products differ so much, it is best to check with your pharmacist or doctor to help you choose a reputable product and a sensible amount. Drinking black tea is a simpler, well-tolerated way to get theaflavins for most people.

Pregnancy & Breastfeeding

Theaflavin & Pregnancy

Insufficient reliable information

Insufficient reliable information available; avoid using.

Theaflavin & Breastfeeding

Insufficient reliable information

Insufficient reliable information available; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

© 2026 Therapeutic Research Center

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 4 references that drive our Theaflavin monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Maron DJ, Lu GP, Cai NS, et al. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med 2003;163:1448-53.. PubMed
  2. Takemoto M, Takemoto H, Kouno H, Soeda T, Moriya T. A simple, enzymatic biotransformation method using fresh green tea leaves efficiently generates theaflavin-containing fermentation water that has potent physiological functions in mice and humans. Biol P PubMed
  3. Kondo A, Narumi K, Okuhara K, et al. Black tea extract and theaflavin derivatives affect the pharmacokinetics of rosuvastatin by modulating organic anion transporting polypeptide (OATP) 2B1 activity. Biopharm Drug Dispos. 2019;40(8):302-306. PubMed
  4. Gothandam K, Ganesan VS, Ayyasamy T, Ramalingam S. Antioxidant potential of theaflavin ameliorates the activities of key enzymes of glucose metabolism in high fat diet and streptozotocin - induced diabetic rats. Redox Rep. 2019;24(1):41-50. PubMed
Keep reading

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.

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

Brand directory

Brands that make products with Theaflavin

3 brands in our database make a supplement containing Theaflavin.

Product directory

Supplement products with Theaflavin

11 products in our database contain Theaflavin. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Theaflavin: Common Questions

What is Theaflavin used for, and does it work?
People use Theaflavin for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.
Does Theaflavin interact with prescription medications?
Yes. We list 130 medications with a known interaction with Theaflavin. Use the checker above to see how Theaflavin interacts with a specific drug.
How are Theaflavin interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Theaflavin with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Theaflavin interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Theaflavin used for?
It is most commonly used for heart and cholesterol health and as an antioxidant, though strong human evidence is limited. It is found naturally in black tea.
Is Theaflavin the same as drinking black tea?
Theaflavins are compounds found in black tea, so drinking black tea provides them naturally. Supplements offer a more concentrated dose from black tea extract.
Can I take Theaflavin if I'm pregnant or breastfeeding?
It's safest to limit caffeine-containing tea and avoid concentrated extracts during pregnancy and breastfeeding, since supplement safety isn't well studied. Check with your doctor first.
Does Theaflavin have caffeine?
Black tea naturally contains caffeine, so teas and some extracts may contain it. Check the label, especially if you are sensitive to caffeine.

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

Keep exploring

Products that contain Theaflavin

A rotating sample of real supplements in our database that list Theaflavin — open any to see its full ingredients and every drug interaction we check.

See all 11 products with Theaflavin →
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