Interaction Details

Metformin is classified as belonging to the following category: Antidiabetes Drugs

Theoretically, Ceylon cinnamon may have additive effects with antidiabetes drugs.
Ceylon cinnamon may lower blood glucose levels. Dose adjustments might be necessary.

Interaction Rating


Likelihood of Occurrence


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

Pharmacist Analysis

It is important to note that although cinnamon has a mild blood sugar-lowering effect, it is not generally associated with causing hypoglycemia.

This is likely due to how cinnamon purportedly works to lower blood sugar. It does not stimulate the release of insulin, but rather, increases our the body's sensitivity to insulin. This allows insulin to more effectively move glucose from the bloodstream into cells where it can be used for energy, which helps reduce blood glucose levels.

Even though it is important to be aware of the fact that, theoretically, cinnamon could interact with other drugs that lower blood sugar due to an additive effect, in general, this interaction isn't overly clinically significant with many drugs used for diabetes that also carry only a low risk of hypoglycemia (like metformin).

There may be more of a concern with drugs that directly affect insulin, like sulfonylureas (e.g., glipizide), and in those who take insulin itself.



  • Anderson RA, Broadhurst CL, Polansky MM, et al. Isolation and Characterization of Polyphenol Type-A Polymers from Cinnamon with Insulin-like Biological Activity. J Agric Food Chem 2004;52:65-70.
  • Jarvill-Taylor KJ, Anderson RA, Graves DJ. A hydroxychalcone derived from cinnamon functions as a mimetic for insulin in 3T3-L1 adipocytes. J Am Coll Nutr 2001;20:327-36.
  • Onderoglu S, Sozer S, Erbil KM, et al. The evaluation of long-term effcts of cinnamon bark and olive leaf on toxicity induced by streptozotocin administration to rats. J Pharm Pharmacol 1999;51:1305-12.

Ceylon Cinnamon Overview

Ceylon Cinnamon Ceylon cinnamon, sometimes known as "true" cinnamon, is a type of cinnamon that is native to Sri Lanka. It is a member of the Cinnamomum verum species and is known for its light, sweet flavor and light brown color. Ceylon cinnamon is considered to be of higher quality and is more expensive than other types of cinnamon, such as cassia cinnamon (which is more common in the United States). Ceylon cinnamon is often used in cooking and baking to add spice and flavor to dishes. The bark of Ceylon cinnamon, which contains cinnamaldehyde, is used in traditional medicine treat a variety of conditions, including indigestion, diabetes, and high cholesterol.

Metformin Overview

  • Metformin is used alone or with other medications, including insulin, to treat type 2 diabetes (condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood). Metformin is in a class of drugs called biguanides. Metformin helps to control the amount of glucose (sugar) in your blood. It decreases the amount of glucose you absorb from your food and the amount of glucose made by your liver. Metformin also increases your body's response to insulin, a natural substance that controls the amount of glucose in the blood. Metformin is not used to treat type 1 diabetes (condition in which the body does not produce insulin and therefore cannot control the amount of sugar in the blood).

  • Over time, people who have diabetes and high blood sugar can develop serious or life-threatening complications, including heart disease, stroke, kidney problems, nerve damage, and eye problems. Taking medication(s), making lifestyle changes (e.g., diet, exercise, quitting smoking), and regularly checking your blood sugar may help to manage your diabetes and improve your health. This therapy may also decrease your chances of having a heart attack, stroke, or other diabetes-related complications such as kidney failure, nerve damage (numb, cold legs or feet; decreased sexual ability in men and women), eye problems, including changes or loss of vision, or gum disease. Your doctor and other healthcare providers will talk to you about the best way to manage your diabetes.

Ceylon Cinnamon - More Interactions

Ceylon Cinnamon interacts with 252 drugs

Interaction Rating Key

These severity listings are for informational use only. Never start, stop or otherwise change your therapy before speaking with your provider.

Major The combined use of these agents is strongly discouraged as serious side effects or other negative outcomes could occur.
Moderate Use cautiously under the care of a healthcare professional or avoid this combination. A significant interaction or negative outcome could occur.
Minor Be aware that there is a chance of an interaction. Watch for warning signs of a potential interaction.
Unknown No interactions have been reported or no interaction data is currently available.

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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

Drug descriptions are provided by MedlinePlus.

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Dr. Brian Staiger, PharmD

In addition to being a clinical pharmacist specializing in pharmacotherapy, Dr. Brian Staiger is a registered herbalist through the American Herbalist Guild. He has combined his passion for pharmacy practice with the study of medical ethnobotany to improve patient care. Feel free to reach out about any of your herbal or medication questions!

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