Rahul Arora, in Food Toxicology and Forensics, 2021 11.4.1 Comfrey For internal applications, comfrey has been used as infusions and extracts for the treatment of gastritis, gastroduodenal ulcers, and lung congestion ( Roeder, 1995). Humans have widely consumed comfrey as a vegetable and taken comfrey formulations of tea or tablets. A herbal practitioner survey of the external use of comfrey in the United Kingdom indicated that comfrey is rated most effective for fractures, wounds, post-surgery healing, and problems with tendon, ligament, and muscle while it is less effective for treating boils, hemorrhoids, and varicose veins ( Frost et al., 2014). Several randomized, controlled trials have demonstrated the efficacy of topical comfrey preparations in the treatment of muscle and joint pain ( Staiger, 2012). Comfrey is applied externally in the form of extracts, ointments, or compress pastes of comfrey leaves and roots to treat joint inflammatory disorders, wounds, bone fractures, gout, hematomas, and thrombophlebitis. Comfrey has been used both internally and externally as a herbal medicine for more than 2000 years in many countries ( Rode, 2002). (the major comfrey species), Symphytum asperum Lepech, Symphytum x uplandicum Nyman, Symphytum tuberosum L., and Symphytum caucasicum Bieb ( Mei et al., 2010b). Lei Guo, in Nutraceuticals (Second Edition), 2021 Therapeutic use of comfreyĬomfrey belongs to the plant family Boraginaceae and there are at least five species referred to as comfrey, including Symphytum officinale L. Sometimes there is also damage to the lungs. They can produce veno-occlusive disease of the liver with clinical features like abdominal pain with ascites, hepatomegaly, splenomegaly, anorexia, nausea, vomiting, and diarrhea. Certain representatives of this class and the plants in which they occur are hepatotoxic, as well as mutagenic and carcinogenic.

Symphytum officinale contains pyrrolizidine alkaloids, which are the subject of a separate monograph.

Herbal medicines that provide more than 1 mg internally or more than 100 mg externally per day, when used as directed, are not permitted herbal medicines that provide 0.1–1 mg internally or 10–100 mg externally per day, when used as directed, may be applied only for a maximum of 6 weeks per year, and they should not be used during pregnancy or lactation. The German Federal Health Office has restricted the availability of botanical medicines containing unsaturated pyrrolizidine alkaloids. Symphytum officinale (black wort, boneset, bruise wort, comfrey, knitback, knitbone, slippery root) contains pyrrolizidine alkaloids, such as lasiocarpine and symphytine, and their N-oxides, and has repeatedly been associated with hepatotoxicity.Ĭomfrey products have been withdrawn from the market in several countries, including the USA and the UK. In Meyler's Side Effects of Drugs (Sixteenth Edition), 2016 Symphytum officinale