Drug & supplement interaction

Chaga + Metformin

Metformin brand names: Glucophage, Metformin.

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

Chaga has a moderate interaction with Metformin. Theoretically, taking chaga with antidiabetes drugs might increase the risk of hypoglycemia.

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

Chaga 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 Chaga interacts with.

Theoretically, taking chaga with antidiabetes drugs might increase the risk of hypoglycemia.
Animal research suggests that chaga might decrease blood glucose levels and increase insulin levels. This has not been reported in humans.
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: Chaga may have its own mild blood sugar lowering effect, and metformin is already working to bring your sugar down. Put them together and, in theory, your levels could dip a little lower than expected. That can show up as feeling shaky, sweaty, lightheaded, hungry, or unusually tired.

I want to be honest about the strength of this, though. This concern comes from animal studies only, where chaga lowered glucose and raised insulin. It hasn't actually been reported in people, so it's more of a theoretical caution than a proven problem. Metformin alone rarely causes true lows. Still, if you'd like to add chaga, check with your pharmacist or doctor first and keep an eye on your numbers.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sun JE, Ao ZH, Lu ZM, et al. Antihyperglycemic and antilipidperoxidative effects of dry matter of culture broth of Inonotus obliquus in submerged culture on normal and alloxan-diabetes mice. J Ethnopharmacol 2008;118(1):7-13. PubMed
  2. Su L, Xin C, Yang J, et al. A polysaccharide from Inonotus obliquus ameliorates intestinal barrier dysfunction in mice with type 2 diabetes mellitus. Int J Biol Macromol 2022;214:312-323. PubMed
  3. Chen S, Ma Y, Li H, et al. Anti-diabetic e?ects of Inonotus obliquus extract in high fat diet combined streptozotocin-induced type 2 diabetic mice. Nutr Hosp 2022;39(6):1256-1263. PubMed
  4. Ye X, Wu K, Xu L, et al. Methanol extract of Inonotus obliquus improves type 2 diabetes mellitus through modifying intestinal flora. Front Endocrinol (Lausanne) 2023;13:1103972. 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

Chaga Also Interacts With Other Medications

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

Check Another of Your Medications Against Chaga

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

From our Q&A

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

We hold 889 real supplement products containing Chaga, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Chaga. Your product may carry other ingredients that interact with Metformin too, on top of Chaga — 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 Chaga 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 Chaga
Top 25%

#280 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 Chaga

What is Chaga?

  • Immune support
  • Antioxidant support
  • General wellness/tonic
  • Blood sugar support
  • Inflammation

Chaga is a fungus that grows mostly on birch trees and is used as a tea or supplement, mainly for immune and antioxidant support. Human evidence for its benefits is very limited, and it may raise some safety concerns such as effects on blood sugar, bleeding, and kidney stones. Talk with your pharmacist or doctor before using it, especially if you have a health condition or take other medicines.

Read the full Chaga 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 & Chaga

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

No interaction 2,503 drugs checked — show the list

We also checked Chaga 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 Chaga list.

See the full Chaga 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
Chaga 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 Chaga and Metformin Together: Common Questions

Can you take Chaga 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 Chaga 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 Chaga?

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.