Drug & supplement interaction

Inositol + Metformin Hydrochloride

Metformin Hydrochloride brand name: Riomet ER.

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

Inositol has a moderate interaction with Metformin Hydrochloride. Theoretically, taking inositol with antidiabetes drugs might increase the risk of hypoglycemia.

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

Inositol 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 Inositol interacts with.

Theoretically, taking inositol with antidiabetes drugs might increase the risk of hypoglycemia.
Clinical research shows that inositol lowers blood glucose levels and glycated hemoglobin (HbA1c) levels in patients with diabetes.
Severity Moderate Likelihood Possible Evidence A

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: both metformin and inositol work to lower your blood sugar, just through different routes. Metformin helps your body respond better to insulin, and inositol seems to support those same insulin-signaling pathways inside your cells. When you stack two blood-sugar-lowering helpers together, the numbers can sometimes dip lower than expected.

This isn't a dangerous clash, and metformin on its own rarely causes serious low blood sugar. But added to inositol, you might notice shakiness, sweating, dizziness, or hunger, especially if you also take other diabetes meds. The evidence that inositol lowers glucose and HbA1c is solid, so it's worth a heads-up. Don't change anything on your own. Just let your pharmacist or doctor know so they can keep an eye on your readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Zheng X, Liu Z, Zhang Y, et al. Relationship Between Myo-Inositol Supplementary and Gestational Diabetes Mellitus: A Meta-Analysis. Medicine (Baltimore). 2015;94(42):e1604. PubMed
  2. Crawford TJ, Crowther CA, Alsweiler J, Brown J. Antenatal dietary supplementation with myo-inositol in women during pregnancy for preventing gestational diabetes. Cochrane Database Syst Rev. 2015;(12):CD011507. PubMed
  3. Maurizi AR, Menduni M, Del Toro R, et al. A pilot study of D-chiro-inositol plus folic acid in overweight patients with type 1 diabetes. Acta Diabetol. 2017;54(4):361-65. 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

Inositol Also Interacts With Other Medications

Inositol has 85 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 85 No known interaction 2,745 (incl. Metformin Hydrochloride)
Taking anything else?

Check Another of Your Medications Against Inositol

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

From our Q&A

Questions About Inositol or Metformin Hydrochloride

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

This page covers Inositol 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 Inositol as Part of a Dietary Supplement Product? Check It for Interactions

We hold 10,116 real supplement products containing Inositol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Inositol. Your product may carry other ingredients that interact with Metformin Hydrochloride too, on top of Inositol — 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 Inositol 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 Inositol
Top 5%

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

29 days ago today
Medication Metformin Hydrochloride
Top 10%

#158 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 Inositol

What is Inositol?

Inositol
  • Polycystic ovary syndrome (PCOS)
  • Anxiety and panic
  • Depression and mood
  • Insulin and blood sugar support
  • Fertility support
  • Metabolic syndrome

Inositol is a sugar alcohol made naturally in the body and found in many foods, and it is sold as a supplement (often myo-inositol) mainly for PCOS, mood, and metabolic concerns. The strongest evidence is for PCOS-related symptoms, while support for other uses is more limited. It is generally well tolerated, but talk with your pharmacist or doctor before starting it, especially if you are pregnant or have a health condition.

Read the full Inositol monograph & all interactions
Keep checking

Other Drugs & Inositol

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

No interaction 2,744 drugs checked — show the list

We also checked Inositol 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 Inositol list.

See the full Inositol 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
Inositol 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 Inositol and Metformin Hydrochloride Together: Common Questions

Can you take Inositol 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 Inositol 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 Inositol?

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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.