Drug & supplement interaction

Maritime Pine + Metformin Hydrochloride

Metformin Hydrochloride brand name: Riomet ER.

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

Maritime Pine has a moderate interaction with Metformin Hydrochloride. Theoretically, maritime pine bark extract might increase the risk of hypoglycemia when used with antidiabetes drugs.

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

Maritime Pine and Metformin Hydrochloride

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Metformin Hydrochloride

Metformin Hydrochloride falls under ANTIDIABETES DRUGS — the group Maritime Pine interacts with.

Theoretically, maritime pine bark extract might increase the risk of hypoglycemia when used with antidiabetes drugs.
One clinical study shows that maritime pine bark extract decreases blood sugar in patients with diabetes being treated with antidiabetes agents. Monitor blood glucose levels closely. Dose adjustments might be necessary.
Severity Moderate Likelihood Possible Evidence B

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: maritime pine bark (Pycnogenol) may gently lower your blood sugar on its own. Since metformin is already working to bring your glucose down, stacking the two could push your numbers lower than expected. This isn't a dangerous chemical clash, it's more of an additive effect.

Metformin by itself rarely causes true low blood sugar, but adding this supplement could nudge you that way. Keep an eye out for shakiness, sweating, dizziness, or feeling unusually hungry or foggy. The evidence here is fairly limited (one smaller study), so it's a possibility rather than a sure thing. If you'd like to try the supplement, check your glucose a bit more often at first and loop in your pharmacist or doctor before making any changes.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu X, Wei J, Tan F, et al. Antidiabetic effect of Pycnogenol French maritime pine bark extract in patients with diabetes type II. Life Sci 2004;75:2505-13. 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

Maritime Pine Also Interacts With Other Medications

Maritime Pine has 326 moderate known drug interactions in our database — the Metformin Hydrochloride one above is one of them. If you take anything else, check it against the full list below.

Moderate 326 No known interaction 2,504 (incl. Metformin Hydrochloride)
Taking anything else?

Check Another of Your Medications Against Maritime Pine

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

Everything else you take

See Every Supplement That Interacts With Metformin Hydrochloride

This page covers Maritime Pine 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

One more smart check

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

We hold 452 real supplement products containing Maritime Pine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Maritime Pine. Your product may carry other ingredients that interact with Metformin Hydrochloride too, on top of Maritime Pine — 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 Maritime Pine 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 Maritime Pine
Top 25%

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

29 days ago today
Medication Metformin Hydrochloride
Top 10%

#143 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 Maritime Pine

What is Maritime Pine?

Maritime Pine
  • Circulation and vein health
  • Antioxidant support
  • Skin health and aging
  • High blood pressure
  • Joint comfort

Maritime pine bark extract (often sold as Pycnogenol) is a plant-based antioxidant most studied for circulation, vein, and skin health. Some research is promising, but many studies are small or industry-funded, so benefits are not firmly proven. It is generally well tolerated, but talk to your pharmacist or doctor before starting it.

Read the full Maritime Pine monograph & all interactions
Keep checking

Other Drugs & Maritime Pine

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

0Major
326Moderate
0Minor
2,503No known interaction
326 Moderate 2,503 No interaction
Moderate

326 interactions

Showing 60 of 326 moderate interactions — see all 326 on the Maritime Pine page.

No interaction 2,503 drugs checked — show the list

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

Showing the 60 most looked-up of 2,503 medications checked with no known interaction — see the full Maritime Pine list.

See the full Maritime Pine 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
Maritime Pine 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 Maritime Pine and Metformin Hydrochloride Together: Common Questions

Can you take Maritime Pine with Metformin Hydrochloride?
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 Maritime Pine and Metformin Hydrochloride 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 Hydrochloride and Maritime Pine?

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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.