Drug & supplement interaction

Ketogenic Diet + Metformin

Metformin brand names: Glucophage, Metformin.

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

Ketogenic Diet has a moderate interaction with Metformin. Theoretically, following the ketogenic diet while using antidiabetes drugs might increase the risk of hypoglycemia.

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

Ketogenic Diet 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 Ketogenic Diet interacts with.

Theoretically, following the ketogenic diet while using antidiabetes drugs might increase the risk of hypoglycemia.
The ketogenic diet involves a very low intake of carbohydrates, which can result in decreased blood glucose levels in patients taking antidiabetes drugs. In some patients, the need for antidiabetes drugs is reduced. Hypoglycemia has also occurred in some individuals without diabetes, although this is uncommon.
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 thing to keep in mind if you're eating keto while taking metformin. A ketogenic diet keeps your carbohydrates very low, which on its own tends to pull your blood sugar down. Stack that on top of metformin, which already works to lower your glucose, and your numbers can drop lower than you expect. In some people the dose of their diabetes medicine even ends up being more than they need.

Metformin by itself rarely causes true low blood sugar, but combined with very low carbs it becomes more possible. Watch for shakiness, sweating, dizziness, or feeling foggy. This is graded as moderate and partly theoretical, so don't panic, but please loop in your doctor or pharmacist before going full keto. They may want to check your sugars or adjust your plan.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Liu H, Yang Y, Wang Y, et al. Ketogenic diet for treatment of intractable epilepsy in adults: A meta-analysis of observational studies. Epilepsia Open. 2018;3(1):9-17. PubMed
  2. Yancy WS Jr, Westman EC, McDuffie JR, et al. A randomized trial of a low-carbohydrate diet vs orlistat plus a low-fat diet for weight loss. Arch Intern Med. 2010;170(2):136-45. PubMed
  3. Goday A, Bellido D, Sajoux I, et al. Short-term safety, tolerability and efficacy of a very low-calorie-ketogenic diet interventional weight loss program versus hypocaloric diet in patients with type 2 diabetes mellitus. Nutr Diabetes. 2016;6(9):e230. PubMed
  4. Saslow LR, Mason AE, Kim S, et al. An online intervention comparing a very low-carbohydrate ketogenic diet and lifestyle recommendations versus a plate method diet in overweight individuals with type 2 diabetes: A randomized controlled trial. J Med Intern
  5. Hussain TA, Mathew TC, Dashti AA, Asfar S, Al-Zaid N, Dashti HM. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Nutrition. 2012;28(10):1016-21. PubMed
  6. Cervenka MC, Hocker S, Koenig M, et al. Phase I/II multicenter ketogenic diet study for adult superrefractory status epilepticus. Neurology. 2017;88(10):938-943. 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

Ketogenic Diet Also Interacts With Other Medications

Ketogenic Diet has 136 moderate, 122 minor 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 136 Minor 122 No known interaction 2,572 (incl. Metformin)
Taking anything else?

Check Another of Your Medications Against Ketogenic Diet

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

From our Q&A

Questions About Ketogenic Diet 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 Ketogenic Diet 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 Ketogenic Diet 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

How much people look this up

Where Ketogenic Diet 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 Ketogenic Diet
Steady interest

#1,206 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.

Eating pattern

About Ketogenic Diet

What is Ketogenic Diet?

  • Weight loss
  • Type 2 diabetes and blood sugar control
  • Drug-resistant epilepsy (especially in children)
  • Reducing appetite
  • Athletic and metabolic interest

The ketogenic diet is a very low-carbohydrate, high-fat eating plan that shifts the body to burn fat for fuel. It has the strongest evidence as a medical therapy for hard-to-treat epilepsy and may help short-term weight loss and blood sugar, but it can be hard to sustain and is not right for everyone. Talk with a doctor or pharmacist before starting, especially if you have a medical condition or take medication.

Read the full Ketogenic Diet 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 & Ketogenic Diet

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

0Major
136Moderate
122Minor
2,571No known interaction
136 Moderate 122 Minor 2,571 No interaction
Moderate

136 interactions

Showing 60 of 136 moderate interactions — see all 136 on the Ketogenic Diet page.

Minor

122 interactions

Showing 60 of 122 minor interactions — see all 122 on the Ketogenic Diet page.

No interaction 2,571 drugs checked — show the list

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

Showing the 60 most looked-up of 2,571 medications checked with no known interaction — see the full Ketogenic Diet list.

See the full Ketogenic Diet 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
Ketogenic Diet 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

Following Ketogenic Diet While Taking Metformin: Common Questions

Can you follow Ketogenic Diet while taking 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 Ketogenic Diet 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 Ketogenic Diet?

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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.