Drug & supplement interaction

Pu-erh Tea + Metformin Hydrochloride

Metformin Hydrochloride brand name: Riomet ER.

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

Metformin Hydrochloride falls into 2 drug categories that Pu-erh Tea can interact with; the most serious is rated minor. Theoretically, taking pu-erh tea with antidiabetes drugs might interfere with blood glucose control.

Read the full interaction report
SeverityMinor
LikelihoodUnlikely
Interactions2
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Pu-erh Tea and Metformin Hydrochloride

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Pu-erh Tea interacts with whole categories of medication. Metformin Hydrochloride falls into 2 of those categories, so it can interact with Pu-erh Tea in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Minor).

Minor

ANTIDIABETES DRUGS

1 of 2

Why this applies to Metformin Hydrochloride

Metformin Hydrochloride falls under ANTIDIABETES DRUGS — the group Pu-erh Tea interacts with.

Theoretically, taking pu-erh tea with antidiabetes drugs might interfere with blood glucose control.
Pu-erh tea contains caffeine. Reports claim that caffeine might increase or decrease blood sugar levels.
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

Here's the short version: drinking pu-erh tea alongside your metformin is very unlikely to cause a real problem. Metformin works mainly in your liver and gut to lower blood sugar, and it isn't activated or broken down by the same pathways that tea compounds touch, so pu-erh doesn't really change how the drug itself works.

The only loose connection is the caffeine in pu-erh. Caffeine can nudge blood sugar slightly up or down in some people, which is why this shows up as a theoretical interaction. The evidence here is weak, though, and a cup or two of tea is unlikely to matter. If you drink a lot of it or notice unusual highs, lows, or shaky, sweaty feelings, mention it to your pharmacist or doctor. Don't change your metformin on your own.

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
Minor

Metformin (Glucophage)

2 of 2
Theoretically, metformin might increase the levels and adverse effects of caffeine.
Pu-erh 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 the interesting twist with this pairing: it's not really your metformin that's affected. Pu-erh tea contains caffeine, and the concern flows the other way around. Some animal studies hint that metformin may slow how your body clears caffeine. If that holds true in people, the caffeine from your tea could linger a bit longer and feel stronger.

What that might look like is the usual too-much-caffeine stuff: feeling jittery, a racing heart, trouble sleeping, or an upset stomach (which can overlap with metformin's own tendency to cause nausea or loose stools). Honestly, this is theoretical and based only on lab and animal work, so a normal cup or two probably isn't a big deal. If you notice you're wired or sleepless, 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

Pu-erh Tea Also Interacts With Other Medications

Pu-erh Tea has 9 major, 448 moderate, 209 minor known drug interactions in our database — the Metformin Hydrochloride one above is among them. If you take anything else, check it against the full list below.

Major 9 Moderate 448 Minor 209 No known interaction 2,164 (incl. Metformin Hydrochloride)
Taking anything else?

Check Another of Your Medications Against Pu-erh Tea

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

Everything else you take

See Every Supplement That Interacts With Metformin Hydrochloride

This page covers Pu-erh Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin Hydrochloride page lists 257 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 217 moderate · 38 minor.

From our pharmacist’s overview on the Metformin Hydrochloride page

“Anyone taking metformin hydrochloride (Riomet ER) should treat this list with genuine care, because two of its 257 entries are rated major. Siberian cocklebur has caused severe hypoglycemia in people and should not be combined with metformin at all, and activated charcoal can adsorb the drug in the gut so less reaches your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin Hydrochloride interaction page

How much people look this up

Where Pu-erh Tea and Metformin Hydrochloride 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 Pu-erh Tea
Steady interest

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

29 days ago today
Medication Metformin Hydrochloride
Top half

#929 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 Pu-erh Tea

What is Pu-erh Tea?

  • Weight management
  • Cholesterol and heart health
  • Digestion after meals
  • Mental alertness
  • General antioxidant support

Pu-erh tea is a fermented, aged form of tea made from the same plant as green and black tea. It is enjoyed worldwide as a beverage and is sometimes promoted for weight loss, cholesterol, and digestion, but human evidence for these uses is limited. As a normal drink it is generally well tolerated, though it does contain caffeine.

Read the full Pu-erh Tea monograph & all interactions
Keep checking

Other Drugs & Pu-erh Tea

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

9Major
448Moderate
209Minor
2,163No known interaction
9 Major 448 Moderate 209 Minor 2,163 No interaction
Major

9 interactions

Moderate

448 interactions

Showing 60 of 448 moderate interactions — see all 448 on the Pu-erh Tea page.

Minor

209 interactions

Showing 60 of 209 minor interactions — see all 209 on the Pu-erh Tea page.

No interaction 2,163 drugs checked — show the list

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

Showing the 60 most looked-up of 2,163 medications checked with no known interaction — see the full Pu-erh Tea list.

See the full Pu-erh Tea interactions page
See every supplement checked against Metformin Hydrochloride, 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
Pu-erh Tea monograph › Uses, safety, and every drug interaction in one place Metformin Hydrochloride supplement interactions › Every supplement checked against Metformin Hydrochloride, 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 Pu-erh Tea and Metformin Hydrochloride Together: Common Questions

Can you take Pu-erh Tea with Metformin Hydrochloride?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Pu-erh Tea and Metformin Hydrochloride?
Metformin Hydrochloride belongs to more than one drug category, and Pu-erh 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 Pu-erh Tea and Metformin Hydrochloride interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

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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.