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Comfrey (comphrey) extracts are widely used topically and are from the herb Symphytum officinale (close relations are Symphytum × uplandicum and Symphytum asperum). Extracts contain allantoin but from the point of view of ingestion toxicity also contain pyrrolizidine alkaloids such as intermedine, lycopsamine, symphytine, echimidine and symglandine which would be metabolised to cause hepatotoxicity due to for example hepatic veno-occlusive disease.