CinnamonSpice

There's no official recommended daily amount for cinnamon. Clinical studies on blood sugar have used 1–6 g of cassia cinnamon per day for around 40 days without reporting serious short-term adverse events — but that's a study dose, not a safety ceiling.

EFSA's coumarin Tolerable Daily Intake is 0.1 mg/kg body weight/day. For a 60 kg adult, that works out to a coumarin ceiling of about 6 mg/day from all sources combined.

Cassia cinnamon can approach or exceed that ceiling at just fractions of a teaspoon, depending on its coumarin content. Ceylon cinnamon poses much less risk at the same weight, since it contains far less coumarin. ^[6]

Used as a normal cooking spice, cinnamon is considered safe during pregnancy, and there's no evidence that cinnamon tea induces labor.

The NCCIH (National Center for Complementary and Integrative Health) does caution that cinnamon may not be safe in amounts larger than what's typically found in food. So concentrated cinnamon supplements are best avoided without medical advice.

Part of the concern is that cinnamon may reduce platelet count and raise bleeding risk, which matters more around delivery. ^[7]

Ceylon cinnamon ('true cinnamon,' from Cinnamomum verum, native to Sri Lanka) has thin, multi-layered, easily crumbled quills, a milder flavor, and very low coumarin content.

Cassia cinnamon (from Cinnamomum cassia and related species, grown across China and Southeast Asia) has thicker, harder, single-layer sticks, a stronger and spicier flavor, and roughly 250 times more coumarin than Ceylon by one estimate. It's also the type most commonly sold as generic "cinnamon" in supermarkets.

Preliminary research shows both types have similar potential to help manage blood sugar. But Ceylon is the lower-risk pick for anyone consuming cinnamon in larger daily amounts. ^[8]

There's a documented concern here, though not a precisely quantified one. A systematic review notes that in animal studies, cinnamon's coumarin compounds have been associated with decreased platelet counts and increased bleeding risk — relevant for anyone on anticoagulant or antiplatelet therapy.

A separate medically reviewed source advises against cinnamon while on blood-thinning medication for the same reason. Read this as a plausible, precautionary flag from reviewers, not a large confirmed dataset of human interactions. ^[1]

Not at typical culinary intakes, for most people. At high, chronic doses, though, it can be — specifically because of the coumarin in cassia-type cinnamon.

Regulatory risk assessments from EFSA, France's ANSES, and Austria's AGES confirm coumarin is hepatotoxic above the established Tolerable Daily Intake. One published case report describes a woman who developed hepatitis after consuming about 1–2 g of cinnamon daily (an estimated 3.3–6.6 mg of coumarin) for two months.

Individual susceptibility appears to vary. Ceylon cinnamon's much lower coumarin content makes it the lower-risk choice for anyone eating cinnamon in larger daily amounts long-term. ^[9]

Yes. Cinnamon oil and cinnamic aldehyde are recognized contact allergens, and cinnamon-flavored gum, candy, and toothpaste have repeatedly been linked to oral reactions.

Those reactions include burning, red patches, and ulceration, mainly on the inside of the cheeks and sides of the tongue.

These typically resolve within 1–2 days of stopping the cinnamon-flavored product.

Cinnamon can also cause allergic or irritant contact dermatitis on skin that touches it. Occupational exposure — bakers and spice workers, for instance — has been linked to hand or facial dermatitis. ^[5]