Drug & supplement interaction

Black Mustard + Metformin

Metformin brand names: Glucophage, Metformin.

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

Black Mustard has a moderate interaction with Metformin. Theoretically, black mustard seed might increase the risk of hypoglycemia when used with antidiabetes drugs.

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

Black Mustard 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 Mustard interacts with.

Theoretically, black mustard seed might increase the risk of hypoglycemia when used with antidiabetes drugs.
Animal research shows that some extracts of black mustard seeds can reduce blood glucose levels, possibly by regulating the release of insulin and the metabolism of glucose.
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 gist for metformin and black mustard. Some animal studies hint that concentrated black mustard seed extracts may nudge blood sugar a bit lower on their own. Since metformin already works to bring your glucose down, stacking the two could, in theory, push your numbers lower than you want. That might show up as shakiness, sweating, a fast heartbeat, dizziness, or feeling unusually hungry or foggy.

I want to keep this in perspective. This is a theoretical concern based on lab and animal work, not strong human evidence. Mustard as a food on your sandwich or in a recipe is very unlikely to matter. Concentrated supplement doses are the part worth watching. If you'd like to try one, check with your pharmacist or doctor first and keep an eye on your readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Anand, P., Murali, K. Y., Tandon, V., Chandra, R., and Murthy, P. S. Preliminary studies on antihyperglycemic effect of aqueous extract of Brassica nigra (L.) Koch in streptozotocin induced diabetic rats. Indian J Exp.Biol 2007;45(8):696-701.
  2. Anand, P., Murali, Y. K., Tandon, V., Murthy, P. S., and Chandra, R. Insulinotropic effect of aqueous extract of Brassica nigra improves glucose homeostasis in streptozotocin induced diabetic rats. Exp.Clin.Endocrinol.Diabetes 2009;117(6):251-256.

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 Mustard Also Interacts With Other Medications

Black Mustard has 85 moderate 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 85 No known interaction 2,745 (incl. Metformin)
Taking anything else?

Check Another of Your Medications Against Black Mustard

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

From our Q&A

Questions About Black Mustard 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 Mustard 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 Mustard 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 Mustard as Part of a Dietary Supplement Product? Check It for Interactions

We hold 77 real supplement products containing Black Mustard, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Mustard. Your product may carry other ingredients that interact with Metformin too, on top of Black Mustard — 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 Mustard 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 Mustard
Top half

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

29 days ago today
Medication Metformin
Top 1%

#29 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 Mustard

What is Black Mustard?

Black Mustard
  • Culinary spice
  • Muscle and joint aches (topical plaster)
  • Chest congestion (chest rub or poultice)
  • Digestive upset
  • Antioxidant and anti-inflammatory support

Black mustard is best known as a pungent culinary spice and a traditional topical remedy for muscle aches and congestion. Solid human evidence for any specific health benefit is limited, and concentrated seed extracts or undiluted oil can irritate or burn the skin. Use it mainly as a food, and talk to a pharmacist or doctor before using it medicinally.

Read the full Black Mustard monograph & all interactions
Medication

About Metformin

What Is Metformin Used For?

Brand names: Glucophage, Metformin

Metformin is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus. It is always used together with diet and exercise, not instead of them.

Metformin hydrochloride tablets and oral solution are approved for adults and children 10 years and older. Metformin hydrochloride extended-release tablets — including brands such as Fortamet, Glumetza, and Metformin Hydrochloride Extended Release — are approved for adults only.

See full Metformin drug information
Keep checking

Other Drugs & Black Mustard

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

0Major
85Moderate
0Minor
2,744No known interaction
85 Moderate 2,744 No interaction
Moderate

85 interactions

Showing 60 of 85 moderate interactions — see all 85 on the Black Mustard page.

No interaction 2,744 drugs checked — show the list

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

Showing the 60 most looked-up of 2,744 medications checked with no known interaction — see the full Black Mustard list.

See the full Black Mustard 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 Mustard 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 Mustard and Metformin Together: Common Questions

Can you take Black Mustard 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 Mustard 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 Mustard?

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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.