Comfrey Herb Tea and Hepatic Veno-Occlusive Disease

Genotoxicity of pyrrolizidine alkaloids

“…The clinical symptoms usually occur suddenly and include vomiting, enlargement of the liver and bleeding diarrhea. Children are more sensitive to PA intoxications than adults (Bach et al, 1989;Bras et al, 1954;Kumana et al, 1985;Mohabbat et al, 1976;Ortiz Cansado et al, 1995;Ridker and McDermott, 1989;Ridker et al, 1985;Schoental and Coady, 1968;Sperl et al, 1995;Tandon et al, 1976;Weston et al, 1987;Yeong et al, 1990).…”

Mutagenicity of comfrey (Symphytum Officinale) in rat liver

“…Comfrey, however, is hepatotoxic in livestock and humans and carcinogenic in experimental animals. It induced hepatic veno-occlusive disease in humans (Ridker et al, 1985;Weston et al, 1987;Bach et al, 1989;Ridker and McDermott, 1989;Yeong et al, 1990) and hepatocellular adenomas and haemangioendothelial sarcomas in rat liver (Hirono et al, 1978). Although there are no epidemiological data regarding the carcinogenicity of comfrey, these adverse effects have raised questions of its potential carcinogenicity in humans.…”

Hepatotoxic Botanicals - An Evidence-based Systematic Review

“…The mechanism of action of comfrey has not been established due to the involvement of multiple constituents (226). Hepatotoxicity of comfrey could be linked to several factors including susceptibility of host, route of exposure as well as ingested dose (43,51). Though, comfrey-induce injury could be due to destruction of veins that cause cirrhosis and finally liver failure (226) or hepatic congestion due to fibrous obliteration of small hepatic veins (54).…”

“…Several studies reported health risk associated with PA. The major hepatotoxic effect of PA is the hepatic venoocclusive disease (VOD) (50,51) that is also known as Sinusoidal obstruction syndrome (52). Portal hypertension with severe ascites is one of major characteristics of VOD disease (53).…”