{"entity":{"id":"comfrey","kind":"technology","name":"Comfrey","aka":[],"tldr":"Comfrey is a garden plant used for wounds and sold in teas and capsules. Taken by mouth it contains alkaloids that damage the liver and cause cancer in animals, and the US regulator asked manufacturers to withdraw comfrey supplements in 2001. Foxglove mistaken for comfrey has caused poisoning and one death.","summary":"Comfrey (Symphytum officinale) leaves and roots have been used for wound healing. Memorial Sloan Kettering's About Herbs summary describes antiproliferative effects of oral comfrey in preclinical work and preliminary data that topical preparations may relieve pain, though a Cochrane review of herbal medicines for low back pain found insufficient evidence. Comfrey contains unsaturated pyrrolizidine alkaloids that MSK describes as hepatotoxic, mutagenic and carcinogenic, and liver damage with oral use is documented in case reports. In June 2001 the US FDA asked manufacturers to remove comfrey-containing dietary supplements from the market, and it is prohibited in Australia and New Zealand. Because foxglove has similar leaves, several people who thought they were drinking comfrey tea suffered cardiac glycoside poisoning, one fatally. There is no evidence that comfrey treats cancer in people.","status":"negative","asOf":"2026-11-04","links":[{"label":"MSK About Herbs: Comfrey (page last updated 8 July 2022)","url":"https://www.mskcc.org/cancer-care/integrative-medicine/herbs/comfrey"}],"tags":["complementary","supportive-care","evidence:harm"],"related":["chaparral-herb","kava-kava"],"cancers":[],"sections":["supportive-care"],"technologies":["integrative-oncology","dietary-supplements-treatment-interactions"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":["b-misinformation"],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"Pyrrolizidine alkaloids are converted in the liver to reactive metabolites that injure the small veins of the liver (veno-occlusive disease) and damage DNA.","strengths":["Topical use for pain has some preliminary data"],"limitations":["Liver-toxic and carcinogenic alkaloids","Oral supplements withdrawn in the US in 2001","Confusion with foxglove has been fatal"]},"route":"/technologies/comfrey/","neighbours":{"technology":[{"id":"chaparral-herb","kind":"technology","name":"Chaparral (creosote bush)","route":"/technologies/chaparral-herb/"},{"id":"dietary-supplements-treatment-interactions","kind":"technology","name":"Dietary supplements during cancer treatment: interactions and harms","route":"/technologies/dietary-supplements-treatment-interactions/"},{"id":"integrative-oncology","kind":"technology","name":"Evidence-based integrative oncology","route":"/technologies/integrative-oncology/"},{"id":"kava-kava","kind":"technology","name":"Kava","route":"/technologies/kava-kava/"}],"section":[{"id":"supportive-care","kind":"section","name":"Supportive Care & Survivorship","route":"/fronts/supportive-care/"}],"bottleneck":[{"id":"b-misinformation","kind":"bottleneck","name":"Misinformation and unproven therapies","route":"/bottlenecks/b-misinformation/"}]}}