Coltsfoot

The flowers, leaves, and roots of coltsfoot have been used as herbal medicines. However, the roots are generally avoided now. Coltsfoot originates in Eurasia and North Africa, and now also grows throughout damp areas of North America.

Coltsfoot historically has been used by herbalists to alleviate coughs due to all manner of conditions. It was considered particularly useful for people with chronic coughs, such as those due to emphysema or silicosis.¹ Coltsfoot leaf was originally approved for the treatment of sore throats in the German Commission E monograph² but has since been banned in Germany for internal use.³

Mucilage, bitter glycosides, and tannins are considered the major constituents of coltsfoot.⁴ These are thought to give the herb anti-inflammatory and antitussive (cough prevention and treatment) activity.⁵ Coltsfoot also contains pyrrolizidine alkaloids, potentially toxic constituents.

Internal use of coltsfoot root is not recommended due to the potential liver toxicity of its pyrrolizidine alkaloids. Tea of coltsfoot leaf or flower is made by steeping 1–2 teaspoons (5–10 grams) in 1 cup (250 ml) hot water for ten to twenty minutes.⁶ People can drink three cups (750 ml) daily. Alternatively, 1/2–1 teaspoon (2–4 ml) of tincture of the leaf or flower can be taken three times per day. Some practitioners of herbal medicine have recommended having hot coltsfoot tea ready in a thermos to drink for morning coughs due to emphysema.⁷ People should not use coltsfoot for more than one month consecutively unless on the advice of a doctor. Also, preparations guaranteed to be pyrrolizidine-free can be used indefinitely and are preferable.

Coltsfoot contains potentially liver-damaging pyrrolizidine alkaloids, with much higher levels appearing in the root than in the leaves or the flowers. Animal studies using amounts of coltsfoot hundreds of times higher than those used as medicine have shown these alkaloids can cause cancer in animals.⁸ A single case of an infant who developed liver disease and died after the mother drank tea containing coltsfoot during pregnancy has been reported.⁹ This eventually led to the banning of coltsfoot in Germany in 1992.

Coltsfoot should not be taken during pregnancy or breast-feeding.¹⁰ Otherwise, coltsfoot is generally safe.¹¹

Coltsfoot should be differentiated from the plant called western coltsfoot (Petastites frigidus), because western coltsfoot can contain higher amounts of pyrrolizidine alkaloids. Use of western coltsfoot is not recommended.