Drug & supplement interaction

Black Pepper + Metformin

Metformin brand names: Glucophage, Metformin.

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

Black Pepper has a moderate interaction with Metformin. Theoretically, black pepper might increase the risk of hypoglycemia when taken with antidiabetes drugs.

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

Black Pepper and Metformin

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ANTIDIABETES DRUGS

Why this applies to Metformin

Metformin falls under ANTIDIABETES DRUGS — the group Black Pepper interacts with.

Theoretically, black pepper might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Animal research shows that piperine, a constituent of black pepper, can reduce blood glucose levels. Monitor blood glucose levels closely. Dose adjustments might be necessary.
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 simple version: black pepper concentrated into a supplement (think piperine extract) may have a mild blood-sugar-lowering effect of its own. Stack that on top of metformin, which is already working to bring your sugar down, and in theory the two could add up and push your glucose a little lower than expected.

I want to be honest about the evidence, though. This is theoretical and comes mostly from animal studies, not solid human research. The sprinkle of pepper on your dinner is very unlikely to matter. Metformin alone rarely causes serious low blood sugar, but if you take piperine supplements regularly, it's worth keeping an eye on your readings and watching for shakiness, sweating, or dizziness. Chat with your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Panda, S. and Kar, A. Piperine lowers the serum concentrations of thyroid hormones, glucose and hepatic 5'D activity in adult male mice. Horm.Metab Res. 2003;35(9):523-526. PubMed

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

Black Pepper Also Interacts With Other Medications

Black Pepper has 975 moderate, 43 minor known drug interactions in our database — the Metformin one above is one of them. If you take anything else, check it against the full list below.

Moderate 975 Minor 43 No known interaction 1,812 (incl. Metformin)
Taking anything else?

Check Another of Your Medications Against Black Pepper

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

From our Q&A

Questions About Black Pepper or Metformin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Black Pepper or Metformin, 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

This page covers Black Pepper only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin page lists 258 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 · 39 minor.

From our pharmacist’s overview on the Metformin page

“Siberian cocklebur is the ingredient I most want anyone taking metformin (Glucophage) to know about. It has caused severe low blood sugar in people, documented in humans, and it should not be combined with any glucose-lowering medication.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin interaction page

One more smart check

Taking Black Pepper as Part of a Dietary Supplement Product? Check It for Interactions

We hold 5,528 real supplement products containing Black Pepper, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Pepper. Your product may carry other ingredients that interact with Metformin too, on top of Black Pepper — 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 Black Pepper and Metformin 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 Black Pepper
Top 5%

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

29 days ago today
Medication Metformin
Top 5%

#32 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 Black Pepper

What is Black Pepper?

Black Pepper
  • Flavoring and culinary use
  • Digestive complaints like bloating and indigestion
  • Boosting absorption of other supplements
  • Antioxidant and anti-inflammatory support
  • Cold and congestion remedies

Black pepper is a common kitchen spice that is generally safe in the amounts used in food. Its extract, piperine, is mostly added to supplements to help the body absorb other ingredients (like curcumin from turmeric). Strong human evidence for black pepper treating specific health conditions is limited, so use supplement-strength products with care and check with your pharmacist.

Read the full Black Pepper monograph & all interactions
Medication

About Metformin

What Is Metformin Used For?

Brand names: Glucophage, Metformin

Metformin — available as tablets, extended-release tablets, and an oral solution — is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus, always as part of a plan that includes diet and exercise.

Metformin hydrochloride tablets and the oral solution are approved for adults and children 10 years and older. Extended-release tablets (including Fortamet, Glumetza, and Metformin Hydrochloride Extended Release) are approved for adults only. Riomet (oral solution) is approved for adults and children 10 years and older.

See full Metformin drug information
Keep checking

Other Drugs & Black Pepper

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

0Major
975Moderate
43Minor
1,811No known interaction
975 Moderate 43 Minor 1,811 No interaction
Moderate

975 interactions

Showing 60 of 975 moderate interactions — see all 975 on the Black Pepper page.

Minor

43 interactions

No interaction 1,811 drugs checked — show the list

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

Showing the 60 most looked-up of 1,811 medications checked with no known interaction — see the full Black Pepper list.

See the full Black Pepper interactions page
See every supplement checked against Metformin, 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
Black Pepper monograph › Uses, safety, and every drug interaction in one place Metformin supplement interactions › Every supplement checked against Metformin, ranked by severity Metformin drug information › The full plain-English guide to this medication 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 Black Pepper and Metformin Together: Common Questions

Can you take Black Pepper with Metformin?
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.
How serious is the Black Pepper and Metformin 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 and Black Pepper?

Our pharmacists answer your medication & supplement questions — free.

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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.