Drug & supplement interaction

Cassia Cinnamon + Metformin, Sitagliptin

Metformin, Sitagliptin brand names: Janumet, Janumet XR.

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

Cassia Cinnamon has a moderate interaction with Metformin, Sitagliptin. Theoretically, cassia cinnamon may have additive effects with antidiabetes drugs.

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

Cassia Cinnamon and Metformin, Sitagliptin

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Metformin, Sitagliptin

Metformin, Sitagliptin falls under ANTIDIABETES DRUGS — the group Cassia Cinnamon interacts with.

Theoretically, cassia cinnamon may have additive effects with antidiabetes drugs.
Cassia cinnamon may lower blood glucose levels, and have additive effects in patients treated with antidiabetic agents. Dose adjustments to diabetes medications 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 thing to keep in mind with Janumet (the combo of metformin and sitagliptin): both of these medicines already work to bring your blood sugar down. Cassia cinnamon, taken as a concentrated supplement, may nudge your blood sugar a little lower on its own. Put them together and the effects can stack, so your sugar could dip more than you expect.

If that happens, you might feel shaky, sweaty, dizzy, or tired (signs of low blood sugar). Honestly, the evidence here is fairly weak and the cinnamon you sprinkle on toast or oatmeal isn't likely to cause trouble. It's the daily high-dose capsules I'd watch. Before starting a supplement, check in with your pharmacist or doctor, and keep an eye on your blood sugar readings.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Khan A, Safdar M, Ali Khan M, et al. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care 2003;26:3215-8. PubMed
  2. Crawford P. Effectiveness of cinnamon for lowering hemoglobin A1C in patients with type 2 diabetes: a randomized, controlled trial. J Am Board Fam Med 2009;22:507-12. PubMed
  3. Akilen, R., Tsiami, A., Devendra, D., and Robinson, N. Glycated haemoglobin and blood pressure-lowering effect of cinnamon in multi-ethnic Type 2 diabetic patients in the UK: a randomized, placebo-controlled, double-blind clinical trial. Diabet.Med. 2010; PubMed
  4. Lu T, Sheng H Wu J Cheng Y Zhu J Chen Y. Cinnamon extract improves fasting blood glucose and glycosylated hemoglobin level in Chinese patients with type 2 diabetes. Nutr Res. 2012;32(6):408-412. PubMed
  5. Stoecker BR, Zhan Z, Luo R, et al. Cinnamon extract lowers blood glucose in hyperglycemic subjects. FASEB J. 2010;22:722.1 (Abstract only). DOI

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

Cassia Cinnamon Also Interacts With Other Medications

Cassia Cinnamon has 441 moderate known drug interactions in our database — the Metformin, Sitagliptin one above is one of them. If you take anything else, check it against the full list below.

Moderate 441 No known interaction 2,389 (incl. Metformin, Sitagliptin)
Taking anything else?

Check Another of Your Medications Against Cassia Cinnamon

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

Everything else you take

See Every Supplement That Interacts With Metformin, Sitagliptin

This page covers Cassia Cinnamon only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin, Sitagliptin 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, Sitagliptin page

“Many people prescribed metformin with sitagliptin (Janumet, Janumet XR) for type 2 diabetes also try herbs sold as blood sugar support, fenugreek among the most popular, and that habit is exactly where the risk on this page concentrates. Of 257 documented supplement interactions, 239 can push glucose in the same direction the medicatio…”

Reviewed by 2 · Jul 18, 2026

Open the Metformin, Sitagliptin interaction page

One more smart check

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

We hold 3,249 real supplement products containing Cassia Cinnamon, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cassia Cinnamon. Your product may carry other ingredients that interact with Metformin, Sitagliptin too, on top of Cassia Cinnamon — 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 Cassia Cinnamon and Metformin, Sitagliptin 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 Cassia Cinnamon
Top 10%

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

29 days ago today
Medication Metformin, Sitagliptin
Top 25%

#610 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 Cassia Cinnamon

What is Cassia Cinnamon?

Cassia Cinnamon
  • Blood sugar support
  • Digestive upset
  • Antioxidant support
  • Flavoring and culinary use
  • Antimicrobial

Cassia cinnamon is the common, inexpensive cinnamon used in cooking, and it is also taken as a supplement, most often for blood sugar support. The evidence for its health benefits is mixed and far from proven, and because cassia is naturally high in coumarin, taking large amounts regularly may stress the liver. Use food amounts freely, but talk with a pharmacist or doctor before using high-dose supplements.

Read the full Cassia Cinnamon monograph & all interactions
Keep checking

Other Drugs & Cassia Cinnamon

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

0Major
441Moderate
0Minor
2,388No known interaction
441 Moderate 2,388 No interaction
Moderate

441 interactions

Showing 60 of 441 moderate interactions — see all 441 on the Cassia Cinnamon page.

No interaction 2,388 drugs checked — show the list

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

Showing the 60 most looked-up of 2,388 medications checked with no known interaction — see the full Cassia Cinnamon list.

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

Can you take Cassia Cinnamon with Metformin, Sitagliptin?
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 Cassia Cinnamon and Metformin, Sitagliptin 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, Sitagliptin and Cassia Cinnamon?

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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.