Herbal Monograph
Cinnamon
Cinnamomum verum J.Presl
Lauraceae
Ancient warming spice with modern blood sugar support — always choose Ceylon ...
Overview
Plant Description
Cinnamomum verum is a small to medium-sized evergreen tree, typically 10–15 m tall in the wild, though maintained as a coppiced bush (2–3 m) in commercial cultivation. The bark is thin, smooth, and pale brown on young branches, becoming rough and grey-brown on older trunks. Leaves are opposite, ovate-lanceolate, 7–18 cm long, coriaceous (leathery), with 3–5 prominent longitudinal veins. Young leaves are characteristically reddish-pink, maturing to dark glossy green above and paler below. Flowers are small, yellowish-white, borne in axillary and terminal panicles, with a distinctly unpleasant odor. Fruit is a dark purple, ovoid drupe approximately 1–1.5 cm long containing a single seed. The medicinally and commercially valuable part is the inner bark (cortex), which is harvested from coppiced shoots. When dried, the thin inner bark curls into the characteristic quills (scrolls) — C. verum quills are notably thinner, more delicate, and multi-layered compared to the thicker, single-scroll quills of C. cassia.
Habitat
Native to the moist tropical forests of Sri Lanka, particularly in the southwestern lowland wet zone at elevations below 500 m. Requires a warm, humid tropical climate with annual rainfall of 1,250–2,500 mm and mean temperatures of 27–30°C. Thrives in well-drained, humus-rich, sandy or lateritic soils with slightly acidic pH (4.5–5.5). Does not tolerate waterlogging or frost. Grows naturally as an understory tree in mixed dipterocarp and tropical evergreen forests.
Distribution
Endemic to Sri Lanka, where it has been cultivated for over 2,000 years. The southwestern coast of Sri Lanka (districts of Galle, Matara, and Ratnapura) remains the world's primary production region for true C. verum cinnamon. Also cultivated in southern India (Kerala, Tamil Nadu, Karnataka), the Seychelles, Madagascar, São Tomé, Comoros Islands, Zanzibar, Egypt, and parts of South America (Brazil) and the Caribbean. Sri Lanka produces approximately 80–90% of the world's true cinnamon (C. verum), with an annual export of 18,000–22,000 tonnes.
Parts Used
Inner bark (Cinnamomi cortex)
Preferred: Powdered bark (capsules or food-grade powder) for blood sugar support; whole quills or bark pieces for decoctions and culinary infusions; tincture for carminative and circulatory applications
The inner bark of coppiced shoots is the primary medicinal and culinary part. It is the subject of the Commission E monograph ('Cinnamomi cortex') and all major pharmacopeial entries for C. verum. The volatile oil (2–4% in C. verum bark) and water-soluble proanthocyanidins are the key therapeutic fractions. Both whole quills and powdered bark are used. Quality is determined by volatile oil content (minimum 1.2% per Ph. Eur.), with fine Ceylon grades containing 2–4%.
Essential oil (Cinnamomi aetheroleum)
Preferred: Steam-distilled bark essential oil; always diluted for topical use (maximum 0.5–1% in carrier oil)
Steam-distilled from the bark or leaves. Bark oil is rich in cinnamaldehyde (65–80%) and is used therapeutically and as a flavoring. Leaf oil has a different chemotype dominated by eugenol (70–85%) rather than cinnamaldehyde, and is pharmacologically distinct. Only bark oil corresponds to the traditional medicinal use of cinnamon. Essential oil is used topically (diluted) and in aromatherapy but requires careful dilution due to potential for skin sensitization (cinnamaldehyde is a known sensitizer).
Key Constituents
Volatile oil (essential oil)
The volatile oil fraction, particularly cinnamaldehyde, is responsible for cinnamon's carminative, antimicrobial, and warming circulatory stimulant actions. Cinnamaldehyde activates TRPA1 receptors in the GI tract, promoting gastric motility and secretion while relieving smooth muscle spasm. The antimicrobial spectrum covers Candida albicans, Staphylococcus aureus, E. coli, Helicobacter pylori, and various food-borne pathogens. Commission E attributes the carminative and appetite-stimulating effects primarily to the volatile oil.
Polyphenols (Proanthocyanidins)
The type-A proanthocyanidins are the primary fraction responsible for cinnamon's insulin-sensitizing and blood glucose-lowering effects. They act as insulin mimetics, enhancing insulin signaling at the receptor level without increasing insulin secretion. This is the key active fraction in cinnamon water-soluble extracts used in clinical trials for type 2 diabetes. Importantly, these compounds are water-soluble and heat-stable, meaning they are present in aqueous extracts, decoctions, and powdered bark preparations — unlike the volatile cinnamaldehyde, which is lost with heat.
Coumarins
Coumarin itself has no therapeutic benefit in cinnamon preparations and is purely a safety concern. It serves as the primary chemical marker for distinguishing C. verum (low coumarin, safe for long-term use) from C. cassia (high coumarin, risk of hepatotoxicity with chronic use at therapeutic doses). Quality-conscious supplement manufacturers specify 'Ceylon cinnamon' or 'C. verum' and may provide certificates of analysis documenting coumarin content.
Diterpenes
Minor fraction but may contribute to the overall insulin-sensitizing profile of cinnamon, working synergistically with the type-A proanthocyanidins.
Mucilage and polysaccharides
Mucilage provides mild demulcent activity, soothing the gastrointestinal mucosa. This complements the carminative action of the volatile oil, making cinnamon preparations well-tolerated for digestive complaints.
Tannins and phenolic acids
The tannin fraction provides the astringent action of cinnamon, useful for diarrhea and excessive mucosal secretions. Together with the volatile oil, this dual action (carminative + astringent) makes cinnamon effective for a range of GI complaints.
Minerals
Not therapeutically relevant. Noted as a constituent for completeness and for pharmacognostic identification purposes.
Herbal Actions
Relieves intestinal gas and bloating
Cinnamon is one of the classic warming carminatives of Western herbalism. The volatile oil (cinnamaldehyde and eugenol) relaxes smooth muscle of the GI tract, relieves intestinal gas and bloating, stimulates peristalsis, and promotes gastric secretion. Commission E approved cinnamon bark specifically for 'loss of appetite' and 'dyspeptic complaints such as mild, spastic conditions of the gastrointestinal tract, bloating, and flatulence.' The warming, aromatic quality makes it particularly suitable for cold, sluggish digestive patterns.
[1, 2, 15]Relieves smooth muscle spasm
Relieves smooth muscle spasm in the gastrointestinal tract. Cinnamaldehyde acts on calcium channels and TRPA1 receptors to reduce excessive contractile activity while maintaining normal peristalsis. This antispasmodic action complements the carminative effect, providing relief from cramping, colic, and spasmodic abdominal pain. Particularly effective when digestive disturbance involves both spasm and gas.
[1, 15, 16]Kills or inhibits the growth of microorganisms
Broad-spectrum antimicrobial activity demonstrated in vitro and in some clinical contexts. Cinnamaldehyde disrupts bacterial and fungal cell membranes, inhibits biofilm formation, and shows activity against Candida albicans, Staphylococcus aureus, E. coli, Helicobacter pylori, Aspergillus species, and various food-borne pathogens. The antimicrobial potency is among the strongest of culinary spice essential oils. Traditionally used to preserve food and as part of anti-infective formulas.
[10, 15, 16]A classic warming circulatory stimulant that improves peripheral blood flow and promotes warmth to the extremities. The volatile oil and cinnamaldehyde cause mild vasodilation of peripheral vasculature. In traditional Western herbalism, cinnamon is combined with ginger and other warming herbs to address cold extremities, chilblains, and sluggish peripheral circulation. The warming energetic quality is central to its traditional use across multiple systems (TCM, Ayurveda, Western).
[4, 15, 16]Tightens and tones tissue, reduces secretions
The tannin and proanthocyanidin content provides a moderate astringent action, tightening and toning tissues, reducing excessive secretions, and helping to control diarrhea. This astringent quality combines with the carminative action to make cinnamon effective for both loose stools with gas and for watery diarrhea. BHP lists cinnamon for diarrhea partly on the basis of this astringent action.
[4, 15]Cinnamon's blood sugar-lowering effect is primarily mediated by the type-A proanthocyanidin fraction, which enhances insulin receptor sensitivity (insulin-mimetic action), increases GLUT4-mediated glucose uptake, and inhibits intestinal alpha-glucosidase (slowing carbohydrate absorption). Multiple meta-analyses of RCTs demonstrate modest but statistically significant reductions in fasting blood glucose (averaging 10–30 mg/dL) and HbA1c in type 2 diabetics. This action is dose-dependent (1–6 g/day of powder or equivalent extract) and is additive with conventional diabetes medications.
[6, 7, 8]Promotes perspiration
The warming quality promotes peripheral vasodilation and mild perspiration, particularly when taken as a hot infusion or decoction. Used traditionally as a warming diaphoretic in the early stages of colds and flu, often combined with ginger, elderflower, and peppermint. Less potent than primary diaphoretics (elder, yarrow) but contributes warming support in combinations.
[4, 15]Stimulates or increases menstrual flow
Traditional reputation as a mild emmenagogue that can stimulate menstrual flow when taken in therapeutic (not culinary) doses. This is the basis for the AHPA class-2b (not for use in pregnancy in therapeutic doses) classification. The mechanism may involve uterine smooth muscle stimulation by cinnamaldehyde. Culinary amounts are not considered emmenagogic.
[3, 15]Therapeutic Indications
Digestive System
Loss of appetite (anorexia)
Commission E approved indication. Cinnamon bark stimulates appetite through aromatic stimulation of gustatory and olfactory receptors, promotion of salivary and gastric secretion, and warming stimulation of the digestive fire. Used as a pre-meal bitter/aromatic or in combination with other appetite-stimulating herbs (gentian, ginger).
[1, 2]Dyspeptic complaints (bloating, flatulence, mild GI spasm)
Commission E approved indication. The dual carminative-antispasmodic action relieves bloating, gas, cramping, and nausea. Particularly suited to 'cold' dyspepsia with sluggish digestion, feelings of fullness, and cold sensations in the epigastrium. The aromatic, warming quality differentiates it from 'cool' carminatives like peppermint.
[1, 2, 15]Diarrhea (non-specific, non-infectious)
The combination of astringent tannins and warming carminative volatile oil makes cinnamon useful for watery diarrhea, particularly when associated with cold, damp digestive patterns. BHP lists it for this indication. Used in Ayurveda for similar purposes. Not appropriate as sole treatment for infectious diarrhea.
[4, 15]Nausea and vomiting
Traditional use as a warming antiemetic, particularly for nausea associated with cold, sluggish digestion. Used in combination formulas for morning sickness (only at culinary doses — not therapeutic doses during pregnancy) and travel sickness. The aromatic volatile oil settles the stomach and reduces reflex nausea.
[15, 16]Endocrine System
Type 2 diabetes mellitus (adjunctive blood sugar support)
Multiple RCTs and meta-analyses demonstrate that cinnamon supplementation (1–6 g/day of powder, or equivalent aqueous extract) produces modest but statistically significant reductions in fasting blood glucose (mean reduction 10–30 mg/dL), HbA1c (mean reduction 0.09–0.5%), and fasting insulin levels in type 2 diabetics. The effect is additive with metformin and sulfonylureas. IMPORTANT: Always specify C. verum for long-term use to avoid coumarin hepatotoxicity risk associated with C. cassia at these doses.
[6, 7, 8]Insulin resistance and metabolic syndrome
The insulin-sensitizing type-A proanthocyanidins improve insulin receptor signaling in vitro and in vivo. Preliminary clinical data suggest beneficial effects on lipid profiles (total cholesterol, LDL, triglycerides) in metabolic syndrome. Further large-scale trials needed for this broader indication.
[7, 8]Polycystic ovary syndrome (PCOS) — insulin resistance component
Small pilot studies suggest cinnamon supplementation may improve insulin sensitivity, menstrual cyclicity, and metabolic parameters in women with PCOS. The mechanism is consistent with the insulin-sensitizing action. Further replication in larger RCTs is needed.
[12]Cardiovascular System
Poor peripheral circulation with cold extremities
Classic traditional indication across Western, Ayurvedic, and Chinese systems. Cinnamon's warming, circulatory-stimulant action improves blood flow to the periphery, relieving cold hands and feet, chilblains, and general feelings of coldness. Used in combination with ginger, cayenne, and prickly ash for circulatory formulas.
[4, 15, 16]Dyslipidemia (adjunctive cholesterol support)
Some clinical trials demonstrate modest reductions in total cholesterol, LDL cholesterol, and triglycerides with cinnamon supplementation. A 2013 meta-analysis found significant reductions in total cholesterol and triglycerides but results were heterogeneous across studies. Not a substitute for standard lipid-lowering therapy.
[7]Respiratory System
Common cold and influenza (early stage)
Used as a warming diaphoretic in the early, chilly stage of colds and flu, particularly when symptoms include chills, shivering, clear nasal discharge, and body aches. Typically combined with ginger, elderflower, and honey as a hot infusion. The antimicrobial volatile oil provides additional benefit. This use is consistent across Western herbalism, Ayurveda (Vata-type cold), and TCM (wind-cold pattern).
[4, 15]Bronchitis with copious clear sputum
Traditional use for 'cold, damp' respiratory conditions with watery or white sputum, chest congestion, and chills. The warming, drying energetic quality helps mobilize and clear cold phlegm. Not appropriate for hot, dry coughs or thick yellow/green sputum (indicating heat).
[15]Reproductive System
Dysmenorrhea (menstrual cramps)
Small RCTs suggest cinnamon supplementation may reduce menstrual pain intensity. A 2015 randomized trial found 420 mg cinnamon three times daily significantly reduced pain severity compared to placebo in primary dysmenorrhea. The antispasmodic and circulatory-stimulant actions provide a plausible mechanism.
[11]Amenorrhea and oligomenorrhea (cold pattern)
Traditional emmenagogue use for scanty or absent menses attributed to cold, stagnant patterns. Used in Ayurveda and Western herbalism for this purpose. The warming, circulatory-stimulating action is thought to promote uterine blood flow and menstrual regularity. Use only in confirmed non-pregnant individuals.
[3, 15]Musculoskeletal System
Joint and muscle pain aggravated by cold and damp
Traditional use for arthritic and rheumatic conditions worsened by cold, wet weather. The warming, circulatory-stimulating properties improve local blood flow, while the anti-inflammatory action of cinnamaldehyde provides modest pain relief. Used topically as a warming liniment (diluted essential oil) and internally as part of warming formulas. In TCM, Gui Zhi (cinnamon twig) is used in the classic formula Gui Zhi Tang for wind-cold bi syndrome.
[15, 16]Immune System
Oral and oropharyngeal candidiasis (thrush)
In vitro studies demonstrate potent antifungal activity of cinnamaldehyde against Candida species, including fluconazole-resistant strains. Cinnamon-containing mouthwashes have shown preliminary clinical efficacy. The in vitro MIC values are among the lowest of any culinary herb. Requires further clinical validation.
[10, 16]Energetics
Temperature
hot
Moisture
dry
Taste
Tissue States
cold/depression, damp/stagnation, damp/relaxation
Cinnamon is one of the hottest and most drying herbs in the Western materia medica. In TCM, Rou Gui (C. cassia bark) is classified as acrid, sweet, and hot, entering the Kidney, Heart, Liver, and Spleen channels — it warms the Kidney yang, promotes circulation, and disperses cold. In Ayurveda, Tvak/Dalchini is pungent (katu), sweet (madhura), heating (ushna virya), and pungent in post-digestive effect (katu vipaka); it pacifies Vata and Kapha while potentially aggravating Pitta in excess. In Western energetics (Hoffmann, Wood, Tierra), it addresses cold/depressive tissue states characterized by sluggish digestion, poor appetite, cold extremities, and damp/stagnant conditions with bloating, loose stools, and excess mucus. It is the archetype of the warming stimulant aromatic. Contraindicated in hot/excitation tissue states and excess Pitta conditions.
Traditional Uses
Traditional Chinese Medicine (TCM)
- Rou Gui (C. cassia bark) — warms the Kidney Yang, strengthens Ming Men fire; used for cold extremities, impotence, infertility, and weakness of the lower back and knees (Kidney Yang deficiency)
- Rou Gui disperses cold, warms the channels, and alleviates pain; used for cold-type abdominal pain, cold painful obstruction (bi syndrome), and amenorrhea due to cold stagnation
- Gui Zhi (C. cassia twigs) — releases the exterior and adjusts Ying and Wei Qi; used in Gui Zhi Tang for wind-cold invasion with sweating
- Gui Zhi warms and opens the channels; used for frozen shoulder, chest painful obstruction (chest bi), and palpitations
- Rou Gui assists in generating Qi and Blood when added to tonic formulas; it 'leads fire back to its source' (guides deficiency heat back to the Kidneys)
"Li Shizhen, Ben Cao Gang Mu (Compendium of Materia Medica, 1578): 'Gui [cinnamon] supplements fire from the source of destiny [Ming Men], it is the essential herb for commanding fire to return to its origin.' The Shen Nong Ben Cao Jing (c. 200 CE) classifies Rou Gui as a superior herb. Note: TCM primarily uses C. cassia, not C. verum, though the pharmacological profiles overlap significantly for most traditional indications."
[17]
Ayurveda
- Tvak (Dalchini) — a warming digestive spice (deepana) that kindles agni (digestive fire) and relieves ama (toxic accumulation)
- Used for poor appetite, sluggish digestion, abdominal distension, and colic (Vata-Kapha digestive disorders)
- Warms the respiratory tract and clears Kapha accumulation; used for productive cough with clear phlegm, rhinitis, and bronchial congestion
- Promotes menstrual flow (artavajnana) and relieves menstrual cramps; used for cold-type dysmenorrhea and amenorrhea
- Supports healthy blood sugar metabolism (Prameha — urinary disorders including diabetes)
- Applied topically for toothache and oral infections (as an analgesic and antimicrobial)
"Tvak is classified in the Charaka Samhita (c. 400 CE) among the Trijata group (three aromatics — cinnamon, cardamom, and bay leaf) used to balance Vata and Kapha. The Bhavaprakash Nighantu (16th century) states: 'Tvak is pungent and sweet in taste, hot in potency, and pungent in post-digestive effect. It is light and dry. It alleviates Vata and Kapha, purifies the blood, and is useful in diseases of the head, rhinitis, and heart diseases.'"
[18]
Western Herbalism (Eclectic and Modern)
- Warming carminative for flatulent dyspepsia, colic, and sluggish digestion with cold, damp presentation
- Warming diaphoretic in early-stage colds and flu, typically combined with ginger and elderflower
- Circulatory stimulant for poor peripheral circulation, cold extremities, and as an adjunct in warming formulas
- Astringent for non-infectious diarrhea and excessive mucosal discharge
- Flavoring agent to improve palatability of bitter or unpleasant herbal formulas
- Emmenagogue for scanty or delayed menses (in non-pregnant women)
"Felter and Lloyd, King's American Dispensatory (1898): 'Cinnamon is a powerful local stimulant, carminative, astringent, and aromatic. It is employed to relieve nausea and vomiting, to check flatulence, and to assist the action of other remedies by stimulating the gastro-intestinal tract.' Hoffmann (2003): 'Cinnamon is used wherever a warming and stimulating effect is needed in the digestive system. It stimulates a sluggish digestion, eases nausea, and helps with diarrhea.'"
Unani-Tibb (Greco-Arabic medicine)
- Darchini (cinnamon) — classified as hot and dry in the second degree; used to warm the stomach and liver
- Used for cold indigestion, flatulence, and to strengthen the stomach and expel gas
- Applied as a warming tonic for the kidneys and bladder; used for urinary frequency from cold constitution
- Used in compound formulas for impotence and sexual weakness attributed to cold temperament
"Ibn Sina (Avicenna), Al-Qanun fi al-Tibb (The Canon of Medicine, c. 1025): classifies Darchini as hot in the second degree and dry in the first degree, with actions to resolve flatulence, strengthen the stomach, and act as an aphrodisiac in cold temperaments."
[20]
Modern Research
Blood glucose regulation in type 2 diabetes
The most extensively studied modern indication. Multiple RCTs and meta-analyses examine the effect of cinnamon supplementation on glycemic parameters in type 2 diabetes mellitus.
Findings: Allen et al. (2013) Cochrane review of 10 RCTs (n=577) found cinnamon supplementation significantly reduced fasting blood glucose (mean difference -0.82 mmol/L [~14.8 mg/dL], 95% CI: -1.63 to -0.01). Davis & Yokoyama (2011) meta-analysis found significant reductions in fasting glucose (pooled mean: -24.59 mg/dL, 95% CI: -40.52 to -8.67) and trends toward reduced HbA1c. Khan et al. (2003) landmark RCT (n=60) showed 1, 3, and 6 g/day of cinnamon reduced fasting glucose by 18–29% after 40 days, with additional reductions in triglycerides, LDL, and total cholesterol. Effects were dose-independent (all three doses equally effective) and persisted for 20 days after cessation.
Limitations: Heterogeneity in cinnamon species used (many studies used C. cassia or did not specify species), dose (0.5–6 g/day), duration (40 days to 4 months), and concomitant medications. Effect sizes were modest. The Cochrane review noted 'no statistically significant effect on HbA1c' in the pooled analysis, though individual trials showed trends. Not all meta-analyses reached the same conclusions, with some (Baker et al. 2008) finding no significant effect. Long-term cardiovascular outcome data are absent.
Insulin-sensitizing mechanism of type-A proanthocyanidins
In vitro and animal studies elucidating the mechanism of cinnamon's insulin-sensitizing action.
Findings: Anderson et al. (2004) identified the type-A proanthocyanidin polymers (trimers to undecamers) as the active insulin-potentiating fraction in aqueous cinnamon extract. These compounds enhance insulin receptor autophosphorylation by 5–20 fold at µg/mL concentrations. They increase GLUT4 translocation to cell membranes in adipocytes and skeletal muscle cells, facilitating glucose uptake. The activity is independent of insulin secretion (insulin-mimetic, not insulin-secretagogue). Additionally, cinnamon extract inhibits intestinal alpha-glucosidase, slowing carbohydrate absorption postprandially.
Limitations: In vitro insulin-potentiating concentrations may not be reliably achieved in vivo after oral administration. Bioavailability and pharmacokinetics of the type-A proanthocyanidins in humans are not fully characterized. Animal model (rodent) results do not always translate to human outcomes.
[9]
Antimicrobial activity
In vitro studies evaluating the broad-spectrum antimicrobial activity of cinnamon bark essential oil and cinnamaldehyde.
Findings: Shan et al. (2007) and multiple subsequent studies demonstrate that cinnamon bark oil and cinnamaldehyde exhibit potent antimicrobial activity against a wide range of pathogens. MIC values for cinnamaldehyde: Candida albicans 0.015–0.06 mg/mL, Staphylococcus aureus 0.25–0.5 mg/mL, E. coli 0.25–0.5 mg/mL, Helicobacter pylori 6.25–12.5 µg/mL. Cinnamaldehyde disrupts cell membrane integrity, inhibits ATPase activity, and prevents biofilm formation. Cinnamon essential oil consistently ranks among the most potent antimicrobial essential oils in comparative studies.
Limitations: In vitro antimicrobial activity does not directly translate to clinical efficacy. Oral bioavailability of cinnamaldehyde is limited by rapid metabolism (conjugation with glutathione). Clinical trials for specific infections are sparse. Topical and local (oral rinse) applications may be more clinically relevant than systemic use.
[10]
Effects on lipid profiles
Clinical trials examining the effect of cinnamon on cardiovascular risk markers including total cholesterol, LDL, HDL, and triglycerides.
Findings: Allen et al. (2013) meta-analysis found cinnamon significantly reduced total cholesterol, LDL, and triglycerides with a non-significant increase in HDL. Khan et al. (2003) showed 12–26% reductions in total cholesterol, 10–24% reductions in triglycerides, and 7–27% reductions in LDL in the treatment groups. These effects may be mediated by the same insulin-sensitizing mechanisms that improve glucose metabolism, as insulin resistance drives dyslipidemia in metabolic syndrome.
Limitations: Lipid effects were secondary outcomes in most diabetes trials. Effect sizes are modest and unlikely to replace statin therapy. Species and dose heterogeneity as with glycemic studies. Long-term cardiovascular outcome data are absent.
Coumarin hepatotoxicity risk — species differentiation
Safety studies and regulatory assessments comparing coumarin content and hepatotoxicity risk across Cinnamomum species.
Findings: The German Federal Institute for Risk Assessment (BfR) issued a risk assessment in 2006 and 2012 highlighting that C. cassia contains approximately 2,100–4,400 mg/kg coumarin, while C. verum contains 0–40 mg/kg (>100-fold difference). EFSA established a tolerable daily intake (TDI) for coumarin of 0.1 mg/kg body weight. At commonly used therapeutic doses of cinnamon (1–6 g/day), C. cassia delivers 2.1–26.4 mg coumarin — exceeding the TDI for most adults. C. verum at the same dose delivers 0–0.24 mg coumarin, well within safe limits. Coumarin hepatotoxicity presents as elevated liver transaminases, typically reversible upon cessation. Susceptibility varies with CYP2A6 genotype (5–10% of the population are poor metabolizers at higher risk).
Limitations: Epidemiological data on cinnamon-related hepatotoxicity are limited to case reports from C. cassia use. No controlled studies have directly compared hepatic safety outcomes between C. verum and C. cassia at therapeutic doses. The TDI is derived primarily from animal data with uncertainty factors.
Dysmenorrhea
Clinical trials examining cinnamon supplementation for primary dysmenorrhea (menstrual pain).
Findings: Jaafarpour et al. (2015) randomized 76 students with primary dysmenorrhea to cinnamon (420 mg three times daily), ibuprofen (400 mg), or placebo for the first 3 days of menstruation. Cinnamon significantly reduced pain severity (VAS) and duration compared to placebo (p<0.05) and showed comparable efficacy to ibuprofen for pain severity. The antispasmodic and anti-inflammatory actions of cinnamaldehyde provide a plausible mechanism.
Limitations: Small sample size (n=76). Single study. Short treatment duration (one menstrual cycle). Further replication in larger, multi-cycle trials is needed.
[11]
Preparations & Dosage
Decoction
Strength: 1:125 to 1:250 (bark to water)
Simmer 1–2 g of crushed cinnamon bark (approximately one 5-cm quill or half a teaspoon of broken quills) in 250 mL water for 10–15 minutes. Strain and drink warm. The prolonged simmering extracts both the volatile oil and the water-soluble proanthocyanidins. Decoction is the traditional method for bark drugs and is preferred over simple infusion for cinnamon.
0.5–1 g of bark per cup, 2–4 g total daily (Commission E: 2–4 g daily of bark)
2–3 times daily, preferably before or with meals
For dyspeptic complaints: as needed. For blood sugar support: minimum 6–8 weeks to assess efficacy; long-term use is safe with C. verum.
Children over 6: half adult dose. Not recommended for children under 6 at medicinal doses.
Decoction extracts both the volatile cinnamaldehyde fraction (partially lost to evaporation with prolonged boiling — keep covered) and the water-soluble type-A proanthocyanidins (the insulin-sensitizing fraction). A covered simmer balances extraction of both fractions. Add honey or fresh ginger for synergistic warming and palatable effect.
Tincture
Strength: 1:5 in 45–70% ethanol (BHP specification)
Tincture of cinnamon bark in 45–70% ethanol. Macerate for 2–4 weeks, shaking daily. The high alcohol percentage is needed to extract the cinnamaldehyde and essential oil components effectively.
0.5–1 mL (10–20 drops) of 1:5 tincture, three times daily
Three times daily, before meals for appetite stimulation; after meals for dyspepsia
As needed for acute GI complaints; 6–12 weeks for ongoing support
Not recommended for children under 12 as a tincture due to alcohol content and pungency
Tincture is the preferred form for carminative and circulatory-stimulant indications in Western herbal practice. The alcohol efficiently extracts the volatile oil (cinnamaldehyde) and provides a convenient dosage form. However, the tincture may not extract the higher-molecular-weight type-A proanthocyanidins as effectively as aqueous preparations, so it is less optimal for blood sugar support compared to powdered bark or water-soluble extract.
Capsule / Powder
Strength: 500 mg standardized powdered bark per capsule (typical commercial formulation)
Powdered C. verum bark in capsules. Use finely ground bark powder from a verified C. verum (Ceylon) source. Ensure the product specifies 'Ceylon cinnamon' or 'C. verum' — most generic cinnamon capsules contain C. cassia unless labeled otherwise.
1–6 g daily of powdered bark (typically 500 mg capsules, 2–12 capsules daily) divided into 2–3 doses taken with meals
Divided into 2–3 doses with meals (particularly important for blood sugar effect — take with carbohydrate-containing meals)
For blood sugar support: minimum 8–12 weeks. Safe for long-term use with C. verum (low coumarin). For C. cassia: limit to 6–8 weeks and monitor liver enzymes.
Not established for supplemental use in children
Capsules of powdered bark deliver the complete phytochemical profile including both the volatile oil fraction (cinnamaldehyde) and the water-soluble proanthocyanidins. This is the form most commonly used in clinical trials for type 2 diabetes. CRITICAL: Verify species — C. verum capsules should contain <0.004% coumarin. Some products provide certificates of analysis. C. cassia capsules at 6 g/day deliver hepatotoxic levels of coumarin with chronic use.
Essential Oil
Strength: Pure steam-distilled bark essential oil; cinnamaldehyde content 55–80%
Cinnamon bark essential oil (Cinnamomi corticis aetheroleum) obtained by steam distillation of the dried inner bark. Use only externally and with appropriate dilution. NEVER ingest undiluted essential oil. For topical use, dilute to 0.5–1% in a carrier oil (jojoba, coconut, almond) to reduce skin sensitization risk.
Topical: 0.5–1% dilution in carrier oil (approximately 1–2 drops per tablespoon of carrier). Aromatic: 2–3 drops in a diffuser or steam inhalation.
Topical: 2–3 times daily to affected area. Aromatic: 15–30 minutes per session.
Short-term topical use (1–2 weeks). Discontinue if irritation occurs.
Not recommended topically for children under 6 due to sensitization risk. Aromatic use with caution in children over 2.
Cinnamaldehyde is a recognized skin sensitizer (IFRA restricted ingredient). Always perform a patch test before first use. Do not apply undiluted to skin. Do not use on mucous membranes. Not for internal use as essential oil — use whole bark preparations for internal therapeutic purposes. Leaf oil (eugenol-dominant) has a different profile and is less sensitizing but also less representative of traditional cinnamon bark medicine.
[21]
Safety & Interactions
Class 2b
Not to be used during lactation (AHPA Botanical Safety Handbook)
Contraindications
Cinnamaldehyde is one of the most common fragrance allergens, causing allergic contact dermatitis in sensitized individuals. Cross-reactivity may occur with other cinnamate-containing products (cosmetics, perfumes, dental products). Oral allergy syndrome (lip/tongue tingling, swelling) has been reported. Avoid all cinnamon preparations in confirmed cinnamon-allergic individuals.
AHPA class 2b: 'Not to be used during pregnancy' at therapeutic doses. Cinnamon is a traditional emmenagogue with potential uterine-stimulating activity at high doses. Cinnamaldehyde has shown uterotonic effects in animal studies. IMPORTANT DISTINCTION: Normal culinary use of cinnamon as a food spice is considered safe during pregnancy and is not contraindicated. The concern applies only to concentrated supplemental doses (>1 g/day as supplement, essential oil, or high-dose tincture).
C. cassia (NOT C. verum) at therapeutic doses (1–6 g/day) delivers coumarin at levels exceeding the EFSA tolerable daily intake, posing hepatotoxicity risk in susceptible individuals. Patients with pre-existing liver disease, elevated liver enzymes, or taking hepatotoxic medications should avoid C. cassia supplementation. C. verum is not contraindicated in liver disease at standard doses due to its negligible coumarin content.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| Insulin (Insulin preparations) | moderate | Cinnamon's insulin-sensitizing type-A proanthocyanidins enhance insulin receptor signaling, potentially amplifying the glucose-lowering effect of exogenous insulin. Additive hypoglycemic effect. |
| Metformin (Biguanides (antidiabetic)) | moderate | Both metformin and cinnamon proanthocyanidins enhance insulin sensitivity through partially overlapping mechanisms (AMPK activation, improved insulin receptor signaling). Additive glucose-lowering effect. |
| Sulfonylureas (glipizide, glyburide, glimepiride) (Insulin secretagogues) | moderate | Additive hypoglycemic effect. Sulfonylureas increase insulin secretion; cinnamon increases insulin sensitivity. The combination could produce excessive glucose lowering. |
| Warfarin and other anticoagulants (Anticoagulants) | minor | Coumarin (present in significant amounts only in C. cassia) is structurally related to warfarin but does not have clinically significant anticoagulant activity at dietary levels. However, C. cassia at very high doses could theoretically contribute to coumarin load. Additionally, cinnamaldehyde has mild antiplatelet properties in vitro. |
| Hepatotoxic drugs (acetaminophen, statins, isoniazid, methotrexate) (Hepatotoxic medications) | minor | C. cassia coumarin adds hepatotoxic burden when combined with other hepatotoxic drugs. Additive hepatotoxicity risk in susceptible individuals (CYP2A6 poor metabolizers). |
Pregnancy & Lactation
Pregnancy
possibly unsafe
Lactation
likely safe
AHPA class 2b: 'Not to be used during pregnancy' at therapeutic doses due to emmenagogue and potential uterotonic activity. CRITICAL DISTINCTION: Normal culinary use of cinnamon as a food spice is universally considered safe during pregnancy and is not restricted. The concern applies only to concentrated therapeutic doses (supplements >1 g/day, essential oil, or high-dose tinctures). There is no evidence of teratogenicity. During lactation, culinary use is safe and cinnamon is a traditional galactagogue in some cultures. High-dose supplementation during lactation has insufficient safety data but is likely safe — the volatile oil compounds are poorly excreted into breast milk.
Adverse Effects
References
Monograph Sources
- [1] Blumenthal, M., Busse, W.R., Goldberg, A., et al.. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines — Cinnamomi cortex (Cinnamon Bark). American Botanical Council / Integrative Medicine Communications (1998) . ISBN: 978-0-9655555-0-0
- [2] World Health Organization. WHO Monographs on Selected Medicinal Plants, Volume 4: Cortex Cinnamomi. World Health Organization, Geneva (2009) . ISBN: 978-92-4-154702-0
- [3] Gardner, Z., McGuffin, M. (eds.). American Herbal Products Association's Botanical Safety Handbook, 2nd Edition. CRC Press (2013) . ISBN: 978-1-4665-1695-3
- [4] British Herbal Medicine Association. British Herbal Pharmacopoeia. BHMA (1983) . ISBN: 978-0-903032-07-1
- [5] European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). Community herbal monograph on Cinnamomum verum J.S. Presl, cortex. EMA/HMPC/246774/2009 (2011)
Clinical Studies
- [6] Khan, A., Safdar, M., Ali Khan, M.M., Khattak, K.N., Anderson, R.A.. Cinnamon improves glucose and lipids of people with type 2 diabetes. Diabetes Care (2003) ; 26(12) : 3215–3218 . DOI: 10.2337/diacare.26.12.3215 . PMID: 14633804
- [7] Allen, R.W., Schwartzman, E., Baker, W.L., Coleman, C.I., Phung, O.J.. Cinnamon use in type 2 diabetes: an updated systematic review and meta-analysis. Annals of Family Medicine (2013) ; 11(5) : 452–459 . DOI: 10.1370/afm.1517 . PMID: 24019277
- [8] Davis, P.A., Yokoyama, W.. Cinnamon intake lowers fasting blood glucose: meta-analysis. Journal of Medicinal Food (2011) ; 14(9) : 884–889 . DOI: 10.1089/jmf.2010.0180 . PMID: 21480806
- [9] Anderson, R.A., Broadhurst, C.L., Polansky, M.M., Schmidt, W.F., Khan, A., Flanagan, V.P., Schoene, N.W., Graves, D.J.. Isolation and characterization of polyphenol type-A polymers from cinnamon with insulin-like biological activity. Journal of Agricultural and Food Chemistry (2004) ; 52(1) : 65–70 . DOI: 10.1021/jf034916b . PMID: 14709014
- [10] Shan, B., Cai, Y.Z., Brooks, J.D., Corke, H.. The in vitro antibacterial activity of dietary spice and medicinal herb extracts. International Journal of Food Microbiology (2007) ; 117(1) : 112–119 . DOI: 10.1016/j.ijfoodmicro.2007.03.003 . PMID: 17449125
- [11] Jaafarpour, M., Hatefi, M., Khani, A., Khajavikhan, J.. Comparative effect of cinnamon and ibuprofen for treatment of primary dysmenorrhea: a randomized double-blind clinical trial. Journal of Clinical and Diagnostic Research (2015) ; 9(4) : QC04–QC07 . DOI: 10.7860/JCDR/2015/12084.5783 . PMID: 26023601
- [12] Kort, D.H., Lobo, R.A.. Preliminary evidence that cinnamon improves menstrual cyclicity in women with polycystic ovary syndrome: a randomized controlled trial. American Journal of Obstetrics and Gynecology (2014) ; 211(5) : 487.e1–487.e6 . DOI: 10.1016/j.ajog.2014.05.009 . PMID: 24813595
- [13] Bundesinstitut für Risikobewertung (BfR — German Federal Institute for Risk Assessment). New insights into coumarin contained in cinnamon. BfR Health Assessment No. 036/2012 (2012)
- [14] Abraham, K., Wöhrlin, F., Lindtner, O., Heinemeyer, G., Lampen, A.. Toxicology and risk assessment of coumarin: focus on human data. Molecular Nutrition & Food Research (2010) ; 54(2) : 228–239 . DOI: 10.1002/mnfr.200900281 . PMID: 20024932
Traditional Texts
- [15] Hoffmann, D.. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press (2003) . ISBN: 978-0-89281-749-8
- [16] Mills, S., Bone, K.. Principles and Practice of Phytotherapy: Modern Herbal Medicine, 2nd Edition. Churchill Livingstone / Elsevier (2013) . ISBN: 978-0-443-06992-5
- [17] Bensky, D., Clavey, S., Stöger, E.. Chinese Herbal Medicine: Materia Medica, 3rd Edition. Eastland Press (2004) . ISBN: 978-0-939616-42-8
- [18] Frawley, D., Lad, V.. The Yoga of Herbs: An Ayurvedic Guide to Herbal Medicine, 2nd Edition. Lotus Press (2001) . ISBN: 978-0-941524-82-4
- [19] Felter, H.W., Lloyd, J.U.. King's American Dispensatory, 18th Edition. Ohio Valley Company (1898)
- [20] Ibn Sina (Avicenna). Al-Qanun fi al-Tibb (The Canon of Medicine). Original manuscript c. 1025 CE; various modern translations available (1025)
Pharmacopeias & Reviews
- [21] Tisserand, R., Young, R.. Essential Oil Safety: A Guide for Health Care Professionals, 2nd Edition. Churchill Livingstone / Elsevier (2014) . ISBN: 978-0-443-06241-4
Last updated: 2026-03-02 | Status: review
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