While people have historically smoked coltsfoot (Tussilago farfara), modern health experts strongly discourage the practice. This perennial plant, native to Europe and Asia, has been used in traditional medicine for centuries. Coltsfoot contains compounds that pose serious risks to human health, particularly when consumed over time. These safety concerns have led to significant medical warnings and regulatory restrictions worldwide.
Traditional Role of Coltsfoot as a Smoking Herb
The practice of smoking coltsfoot leaves has a long history. Its Latin genus name, Tussilago, translates to “cough dispeller,” reflecting its traditional use as a remedy for respiratory ailments. The herb was highly regarded and was famously included in British Herb Tobacco.
People commonly used the dried leaves and flowers as a smoking mixture, often as a non-addictive substitute for tobacco. This mixture was believed to help relieve symptoms of asthma, chronic bronchitis, and persistent coughs. The plant contains mucilage, a gummy substance that forms a soothing film over mucous membranes, which was the basis for its perceived benefit in calming irritated airways.
The Primary Health Concern: Pyrrolizidine Alkaloids
The reason coltsfoot is no longer considered safe is its content of specific toxic compounds known as pyrrolizidine alkaloids (PAs). These are naturally occurring plant toxins produced by the herb, likely as a defense mechanism. The PAs found in coltsfoot are classified as highly hepatotoxic.
These alkaloids are not immediately toxic; instead, they are metabolized in the liver by cytochrome P450 enzymes. This process converts the relatively inert PAs into highly reactive pyrrole metabolites, which are responsible for the damage. The PA content in coltsfoot leaves can vary widely.
The primary health risk associated with exposure to these activated PAs is hepatotoxicity, or severe liver damage. The toxins can cause Veno-Occlusive Disease (VOD), a condition where the small veins in the liver are blocked, leading to tissue damage and potential liver failure. Long-term exposure to these pyrrolizidine alkaloids has also been classified as potentially carcinogenic.
Modern Safety Consensus and Medical Warnings
Due to the confirmed presence of hepatotoxic pyrrolizidine alkaloids, modern medical and regulatory bodies strongly advise against the use of coltsfoot. Health experts generally classify the herb as “LIKELY UNSAFE” for oral consumption, including teas and herbal mixtures. The duration of use is a major factor, as liver damage often results from chronic or repeated exposure.
Several international health agencies have restricted its availability. The European Medicines Agency (EMA) recommends a maximum duration of two weeks of continuous use. Countries like Germany and Austria have restricted or prohibited the sale of coltsfoot for internal use entirely.
Coltsfoot is specifically contraindicated for several vulnerable groups due to the severe risks PAs pose. It is considered unsafe during pregnancy and while breastfeeding because the toxins can cause birth defects and liver damage in the fetus or infant. Individuals with existing liver disease or children should also avoid consuming the herb completely. Safer alternatives exist for soothing respiratory irritation, such as marshmallow root or mullein, which provide similar mucilage-based effects without the risk of pyrrolizidine alkaloid toxicity.