Which Herbs Have Coumarin? A Comprehensive Guide

November 18, 2025 •

3 min read

Coumarin, a fragrant organic compound known for its sweet, fresh hay-like scent, is found naturally in more than 600 plant species. While it is a common natural flavoring, particularly in cinnamon, excessive intake from high-coumarin herbs can pose a risk of liver damage for some individuals.

Quick Summary

This guide identifies common herbs containing coumarin, distinguishing between high-concentration sources like Cassia cinnamon and safer, low-coumarin alternatives. It addresses the potential health risks associated with high intake and provides advice on mindful consumption and substitutions.

Key Points

Cassia Cinnamon is High in Coumarin: The most common cinnamon variety in stores contains significantly higher coumarin levels than safer Ceylon cinnamon.
TDI Limits Coumarin Intake: Regulatory bodies have established a Tolerable Daily Intake (TDI) for coumarin (0.1 mg/kg body weight) to prevent potential liver damage from excessive consumption.
High-Concentration Herbs: Beyond cinnamon, herbs like sweet clover, sweet woodruff, and tonka beans also contain high amounts of coumarin, especially when dried.
Low-Coumarin Alternatives Exist: Ceylon cinnamon offers a low-risk, flavor-rich alternative for those concerned about coumarin intake.
Monitor High Consumption: Individuals who consume large quantities of cinnamon or use high-coumarin herbal supplements should be mindful of their intake to avoid exceeding the safety limits.
Risk for Liver Conditions: People with pre-existing liver conditions are more susceptible to the hepatotoxic effects of coumarin and should be especially cautious.

Common Herbs High in Coumarin

Coumarin is present in various herbs and plants, with concentrations varying widely. Cassia cinnamon is a well-known source, containing significantly higher levels than Ceylon cinnamon. Other plants with notable coumarin content include tonka beans, sweet clover, and sweet woodruff.

Cassia Cinnamon

This common, inexpensive cinnamon (Cinnamomum cassia) found in many grocery stores has coumarin levels up to 10,000 mg/kg. Due to this high concentration, health authorities advise against excessive consumption, particularly for children and sensitive individuals who could exceed the tolerable daily intake (TDI).

Sweet Clover

Historically used in herbal medicine, sweet clover (Melilotus officinalis) contains a coumarin glycoside. When dried or wilted, this can convert into the anticoagulant dicumarol, which caused hemorrhagic disease in livestock. Dried sweet clover can have a coumarin concentration of 0.4% to 1%.

Sweet Woodruff

Sweet woodruff (Galium odoratum) is used to flavor drinks and, like sweet clover, releases coumarin and its characteristic scent primarily when dried.

Other Notable Plants

Other plants containing coumarin include Tonka beans (very high levels), lavender, green tea, celery and parsley (containing furanocoumarins), fenugreek, licorice root, and citrus peels (bergamot, grapefruit, lemon) which contain coumarins and furanocoumarins.

Health Implications of Coumarin

Moderate dietary coumarin intake is generally safe for most people. The European Food Safety Authority (EFSA) sets a Tolerable Daily Intake (TDI) of 0.1 mg/kg body weight. Risks arise with very high consumption of Cassia cinnamon or concentrated herbal supplements over time.

The primary concern is liver damage, which is typically reversible. In most people, coumarin is metabolized into a harmless compound, but in sensitive individuals or those with reduced CYP2A6 enzyme activity, a potentially toxic metabolite can be produced.

Table: Coumarin Content Comparison


Herb Source	Botanical Name	Coumarin Level (Typical Range)	Primary Use	Associated Health Risks (High Intake)
Cassia Cinnamon	Cinnamomum cassia	Very High (up to 10,000 mg/kg)	Spice, flavoring	Liver damage, especially in sensitive individuals
Ceylon Cinnamon	Cinnamomum verum	Very Low (trace amounts)	"True" cinnamon, baking	Generally considered safe for moderate to high intake
Sweet Clover	Melilotus officinalis	High (0.4–1%)	Herbal remedy, anticoagulant precursor	Liver damage, hemorrhagic disease (when dried/fermented)
Sweet Woodruff	Galium odoratum	High (when dried)	Flavoring agent (drinks)	Liver damage with high intake
Tonka Bean	Dipteryx odorata	Very High (1–3%)	Fragrance, flavoring	Liver damage, restricted in food use in some regions
Celery	Apium graveolens	Low (furanocoumarins)	Culinary herb	Photosensitivity with high intake

Recommended Precautions and Alternatives

To minimize potential risks, especially for those with liver issues, consider these steps:

Choose Ceylon Cinnamon: Use Ceylon cinnamon, which has minimal coumarin, particularly for frequent consumption. Always check product labels.
Moderate Intake: Limit high-coumarin foods if you regularly consume large amounts of items like baked goods with Cassia cinnamon.
Consult a Professional: If you have liver disease or are on anticoagulant medication, speak to a healthcare provider before using coumarin-rich herbs or supplements.

Conclusion

Coumarin is a natural compound in many plants and herbs, including Cassia cinnamon, sweet clover, and sweet woodruff. While generally safe in moderation, high intake, particularly from Cassia cinnamon, can pose a risk of liver damage for some individuals. Choosing low-coumarin alternatives like Ceylon cinnamon and being mindful of consumption levels are key to enjoying the flavors of these herbs while minimizing potential health concerns. For most people, dietary coumarin is within safe limits, but awareness allows for informed choices about herbal and spice use.

The European Food Safety Authority (EFSA) provides detailed information on coumarin metabolism and safety.

Frequently Asked Questions

Coumarin is a naturally occurring aromatic organic compound found in many plants. It is known for its sweet, pleasant, and vanilla-like fragrance, reminiscent of fresh-cut hay.

No, there are two main types of cinnamon. Cassia cinnamon contains high levels of coumarin and is the most common variety sold in stores. Ceylon, or 'true' cinnamon, contains only trace amounts and is considered the safer option for frequent consumption.

In large doses and with prolonged use, coumarin can cause liver damage, especially in sensitive individuals. However, occasional, moderate consumption of coumarin-containing foods is generally considered safe for the majority of people.

Exercise caution with supplements containing Cassia cinnamon, sweet clover, or other high-coumarin herbs. Always check product labels for ingredients and consult a healthcare provider for advice, especially if you have liver issues.

For baking and cooking, Ceylon cinnamon is the best low-coumarin alternative. Other warming spices like ginger, cloves, and cardamom can provide similar flavor profiles without the high coumarin risk.

Yes, green tea contains small amounts of coumarin. The concentration can vary based on processing methods and the part of the plant used.

Yes, an individual's metabolism plays a significant role. Some people, particularly those with certain liver enzyme variations (CYP2A6), may be more susceptible to coumarin's hepatotoxic effects. It's recommended to follow guidelines and consult a doctor if concerned.