Cinnamon Tea: What Research Shows About the Tea, Safety and Cautions

Which cinnamon is in the tea matters. Cassia cinnamon contains coumarin, a chemical that has been linked to liver effects. NCCIH says cassia is the most common type sold in North America. [1] It says coumarin-liver interactions have been reported, some cassia products contain high levels, and prolonged use could be an issue for sensitive people such as those with liver disease. [1] Ceylon cinnamon may contain only a trace. [1] If you have liver disease or take medicines for diabetes, ask a pharmacist or clinician before drinking cinnamon tea regularly.

Which plants are called cinnamon

Cinnamon is the dried bark of various Cinnamomum trees (family Lauraceae). Ceylon or "true" cinnamon is Cinnamomum verum J.Presl, grown mainly in Sri Lanka. [1][2] Cassia cinnamon is Cinnamomum aromaticum Nees, the accepted name in the GBIF backbone, also called C. cassia. [1][3] Other cassia species, C. loureiroi and C. burmannii, are also sold in the US as cinnamon. [4] Products may not say which species or bark part was used, and the types differ in chemistry. [1] See Ceylon vs Cassia Cinnamon and Cinnamon (herb profile).

Traditional use

NCCIH reports that cinnamon bark, leaves, flowers, fruits and roots have a long history in traditional medicine and cooking in China, India and Persia (Iran), and that cinnamon was thought to help with inflammation, nerve pain, heart disease and cough. [1] That is traditional use only, not evidence.

What research shows

The tea trial used a cassia-group species, so coumarin matters for that tea. [5][4]

Safety

• Coumarin. The European Food Safety Authority (EFSA) set a tolerable daily intake for coumarin of 0.1 mg per kg of body weight in 2004, based on animal liver toxicity data, as summarized in a 2010 paper. [9] The same paper found heavy users of cassia cinnamon, such as in German holiday baking, may reach that level. [9] Coumarin was found in all cinnamon samples, cinnamon-flavored foods and supplements bought in the US; C. verum bark had only traces. [4] Levels differ between barks, and Vietnamese cinnamon had more than other types in one lab study. [10] We did not read a German BfR statement.
• Diabetes medicines. Because trials report lower blood sugar, people taking diabetes medicines should ask a pharmacist; no source we read documents a specific tea-medicine interaction. See Supplements and Diabetes Medicines.
• Other medicines. NCCIH says there are theoretical reasons to suspect some cinnamon components may interact with an anticancer medicine or with nicotine. [1] See How Interactions Work.
• Pregnancy and breastfeeding. NCCIH says Ceylon cinnamon in larger amounts during pregnancy is considered unsafe. [1] The EU monograph does not recommend use in pregnancy and lactation. [11] The NIH LactMed database says no data exist on cinnamon safety in nursing mothers or infants. [12]
• Children. The EU monograph says use under 18 has not been established. [11]
• Allergy. NCCIH lists stomach problems and allergic reactions as the most common side effects at larger amounts or long use. [1] The EU monograph lists hypersensitivity to the active substance or Peru balsam as a contraindication. [11]
• Never swallow dry cinnamon powder as a dare; NCCIH calls the "cinnamon challenge" unsafe. [1]
• Kidney disease, surgery, older adults: not described in the sources we read.

Official statements

The EU herbal monograph (HMPC, 2011) covers Ceylon cinnamon bark as a traditional herbal medicine for mild spasmodic stomach complaints including bloating and flatulence, and for mild diarrhea. [11] It describes an herbal tea of 0.5 to 1 g of comminuted bark as an infusion up to four times daily for adults, and says to consult a doctor if symptoms last over 2 weeks (stomach complaints) or 2 days (diarrhea). [11] It notes that for diarrhea rehydration should be the first measure. [11] This is a regulator description, not advice for a reader.