Toxicity
Tussilago farfara contains tumorigenic pyrrolizidine alkaloids. Senecionine and senkirkine, present in coltsfoot, have the highest mutagenetic activity of any pyrrolozidine alkaloid, tested using Drosophila melanogaster to produce a comparative genotoxicity test. There are documented cases of Coltsfoot tea causing severe liver problems in an infant, and in another case, an infant developed liver disease and died because the mother drank tea containing coltsfoot during her pregnancy. In response the German government banned the sale of coltsfoot. Clonal plants of colstfoot free of pyrrolizidine alkaloids were then developed in Austria and Germany. This has resulted in the development of the registered variety Tussilago farfara Wein which has no detectable levels of these alkaloids.
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