Drug & supplement interaction

Collard + Glipizide, Metformin

Glipizide, Metformin brand name: Metaglip.

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

Collard has a moderate interaction with Glipizide, Metformin. In an animal study, an aqueous extract of collard leaves and stems has been shown to reduce glucose levels.

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

Collard and Glipizide, Metformin

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Glipizide, Metformin

Glipizide, Metformin falls under ANTIDIABETES DRUGS — the group Collard interacts with.

In an animal study, an aqueous extract of collard leaves and stems has been shown to reduce glucose levels. Collard extract 60 mg/kg lowers blood glucose levels in a rat model of diabetes after both single- and multi-dose oral administration similarly to glibenclamide 5 mg/kg. Theoretically, collard extract might have additive effects when used concomitantly with antidiabetes drugs and may increase the risk of hypoglycemia. Monitor blood glucose levels closely. Dose adjustments may be necessary. Some antidiabetes drugs include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), and tolbutamide (Orinase).
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

Metaglip combines two diabetes medicines: glipizide, which pushes your pancreas to make more insulin, and metformin, which helps your body use insulin better. Both work to bring your blood sugar down. Here's the wrinkle with collard: in a rat study, a concentrated collard leaf extract lowered blood sugar about as well as a diabetes drug. So in theory, layering that on top of Metaglip could add up and nudge your sugar too low.

I want to be honest about how thin this evidence is. It's an animal study using a concentrated extract, not eating collard at dinner. Normal food amounts almost certainly won't cause trouble. If you start a strong collard supplement, watch for low-sugar signs (shakiness, sweating, dizziness) and check in with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Amssayef A, Eddouks M. Antihyperglycemic Effect of the Moroccan Collard Green (Brassica oleracea var. viridis) in Streptozotocin-Induced Diabetic Rats. Endocr Metab Immune Disord Drug Targets 2020. 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

Collard Also Interacts With Other Medications

Collard has 85 moderate known drug interactions in our database — the Glipizide, 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. Glipizide, Metformin)
Taking anything else?

Check Another of Your Medications Against Collard

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

Everything else you take

See Every Supplement That Interacts With Glipizide, Metformin

This page covers Collard only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Glipizide, Metformin page lists 307 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), Adrafinil (moderate) and African Wild Potato (moderate).

By severity: 2 major · 257 moderate · 48 minor.

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

“Glipizide and metformin (Metaglip) already work hard to pull blood sugar down, which is exactly why this list of 307 ingredients deserves genuine vigilance rather than a shrug. Most of them, 239, can lower glucose on their own, and stacked on this pill the combined effect can tip into true hypoglycemia.”

Reviewed by 2 · Jul 18, 2026

Open the Glipizide, Metformin interaction page

One more smart check

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

We hold 379 real supplement products containing Collard, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Collard. Your product may carry other ingredients that interact with Glipizide, Metformin too, on top of Collard — 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 Collard and Glipizide, 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 Collard
Top half

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

29 days ago today
Medication Glipizide, Metformin
Steady interest

#1,728 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 Collard

What is Collard?

  • General nutrition and vitamin source
  • Bone health
  • Heart health support
  • Digestive fiber
  • Antioxidant intake

Collard is a leafy green vegetable in the cabbage family that is rich in vitamins, minerals, and fiber, and is best thought of as a nutritious food rather than a medicine. Eating it as part of a balanced diet is healthy for most people, but there is little high-quality research on collard as a concentrated supplement. If you take blood thinners or have kidney concerns, talk with your pharmacist or doctor because of its vitamin K and oxalate content.

Read the full Collard monograph & all interactions
Keep checking

Other Drugs & Collard

Browse every other medication we’ve checked against Collard — 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 Collard page.

No interaction 2,744 drugs checked — show the list

We also checked Collard 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 Collard list.

See the full Collard interactions page
See every supplement checked against Glipizide, 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
Collard monograph › Uses, safety, and every drug interaction in one place Glipizide, Metformin supplement interactions › Every supplement checked against Glipizide, Metformin, 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 Collard and Glipizide, Metformin Together: Common Questions

Can you take Collard with Glipizide, 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 Collard and Glipizide, 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

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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.