Cinnamon is a popular spice mainly used for its flavor; however, scientific research about cinnamon nutrition has led to a variety of commercial forms, such as cinnamon supplements, cinnamon extract, and cinnamon oil.
The benefits of cinnamon for human health are many; however, studies have also reported about cinnamon's possible side effects, indicating that it should be consumed with caution.
Most Reported Cinnamon Side Effects
Cinnamon is considered to be safe and beneficial for consumption; however, common adverse effects have been reported, especially due to one key cinnamon component called coumarin. This chemical can be found in many plants, including the two main types of cinnamon, Cinnomomum verum, popularly called real cinnamon, and Cinnomomum cassia, also known as cassia or Chinese cinnamon.
The amount of coumarin in true cinnamon (C. verum) is so low that it has been deemed safe; however, according to the German Federal Institute for Risk Assessment, one teaspoon of cassia, or Chinese cinnamon, powder contains 5.8-12.1 mg of coumarin.1 If taken in high doses over a long period of time, it can cause liver and kidneys damage. This level of cinnamon toxicity can cause uncomfortable but reversible symptoms, such as mild dizziness, diarrhea, and vomiting.
Bear in mind that even low doses of coumarin can cause liver damage in sensitive individuals during a long period of consumption.
Uncommon Cinnamon Side Effects
The topical use of cinnamon essential oil can result in skin reactions in some individuals. The high percentage of cinnamldehyde (80%) in cinnamon essential oils may cause irritation, urticaria, contact dermatitis, and rosacea.
It is vital when using cinnamon essential oil to make sure it is properly diluted before application.
Oral cinnamon products, like herbal toothpastes and chewing gums, may cause oral lesions in some individuals. While both of these cinnamon side effects are uncommon, they are possible and, therefore, small doses are recommended for topical or oral use.
Cinnamon Cautions & Interactions
Cinnamon side effects are more likely to occur and could be more severe when consumed by individuals with certain health conditions, or when mixed with other herbs, supplements, or medications.
Heart Conditions. Because cinnamon can increase the heart rate, individuals with heart conditions should avoid taking large doses of the spice.
Pregnancy. The essential oils in cinnamon can cross the placental barrier in pregnant woman. Although little research is available to show its effects during pregnancy and infancy, cinnamon should be used with caution or avoided altogether by pregnant women.
Coronary artery disease. Individuals with coronary artery disease typically have other conditions as well, such as diabetes. When cinnamon is taken with prescribed drugs for these conditions, it can potentially cause liver damage.
Inflammatory liver disorders. The coumarin in cinnamon is damaging to the liver; therefore, it is not recommended for individuals with liver disorders.
BEFORE TAKING ANY HERBAL SUPPLEMENT, PEOPLE WITH PRE-EXISTING CONDITIONS - E.G., CHRONIC ILLNESSES AND GENETIC CONDITIONS - AS WELL AS THOSE WHO ARE PREGNANT OR BREASTFEEDING SHOULD FOLLOW GENERAL PRECAUTIONS IN ACCORDANCE WITH MEDICAL ADVICE.
The Cinnamon Challenge
A very unique but highly publicized cinnamon risk is the severe gag reflex, choking, and pulmonary damage as a result of aspiring or ingesting a large dose of ground cinnamon. An increased awareness of this possible hazard is a consequence of the infamous social media “Cinnamon Challenge,” in which individuals filmed themselves attempting to swallow a tablespoon of ground cinnamon in 60 seconds without drinking fluids. According to the American Association of Poison Control Centers, at least 30 participants in the United States have required medical attention after attempting this challenge.2
While no studies on cinnamon inhalation have been conducted on humans so far, a pre-clinical study on rats published by the Journal of the American Academy of Pediatrics found both immediate and slow-developing effects of cinnamon ingestion.3 A single 15 mg dose of cinnamon dust and cellulose dust showed damaged lung elasticity and alveobronchiolitis in one to seven days and fibrosis after a month.
When consumed along with other medications, cinnamon can cause adverse effects. Cinnamon should be avoided in therapeutic doses when taking the following:
Blood-thinning medications. The anticoagulant abilities of Chinese cinnamon (Cinnamomum cassia) can potentiate the effects of these prescription drugs, increasing the risk of bleeding.
Diabetes medication. All types of cinnamon are able to lower sugar by reducing insulin resistance. In diabetics taking prescribed drugs, therapeutic doses of cinnamon can worsen the hypoglycemic effects.
Cytochrome 450 substrates. Depending on the amounts consumed, the high levels of coumarin in cinnamon - particularly in cassia or Chinese cinnamon - can cause liver damage and inhibit the effects of these medications, which have been formulated to aid the metabolism of toxic compounds.
Statins. These drugs are meant to lower cholesterol by inhibiting its production in the liver. Large amounts of cinnamon can compromise liver function and negatively interact with statins.
Depending on the amounts consumed and individual health conditions, it is possible to experience cinnamon side effects; however, if used in appropriate doses as as a culinary spice rather than medicine, cinnamon is considered safe.
- Institute for Traditional Medicine, An Introduction to Chinese Herbs
- Journal of Food Additives & Contaminants, Coumarin and cinnamaldehyde in cinnamon marketed in Italy: A natural chemical hazard?, 2008
- Memorial Sloan Kettering Cancer Center, Cinnamon
- National Institutes of Health, National Center fo Complementary and Integrative Health, Cinnamon
- Penn State University, Cinnamon and Blood Sugar | Information: Cassia and Cinnamon
- The American Journal of Case Reports, Do Cinnamon Supplements Cause Acute Hepatitis?, 2015
- The Scientific World Journal, Assessment of Coumarin Levels in Ground Cinnamon Available in the Czech Retail Market, 2012
- Tisserand Institute, New Survey Reveals Dangers of Not Diluting Essential Oils
- University of Minnesota, Are Essential Oils Safe?
- University of Washington, Is Cinnamon Good for You?
- Federal Institute for Risk Assessment (BfR). (2012). Cassia cinnamon with high coumarin contents to be consumed in moderation. Retrieved October 25, 2021, from: https://www.bfr.bund.de/en/press_information/2012/26/cassia_cinnamon_with_high_coumarin_contents_to_be_consumed_in_moderation-131836.html
- Injury & Violence. (2015). Lung injury and the cinnamon challenge: college students should beware this Internet dare. Retrieved October 25, 2021, from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4288296/
- Journal of The American Academy of Pediatrics. (2013). Ingesting and Aspirating Dry Cinnamon by Children and Adolescents: The “Cinnamon Challenge”. Retrieved October 25, 2021, from: https://pediatrics.aappublications.org/content/131/5/833