Comfrey has been used medicinally in Japan for more than 2,000 years. It was originally called knitbone because of its topical use as a poultice to heal bruises, burns and swelling. Today, comfrey is used for a variety of ailments. However, comfrey should be used with caution, as it contains toxic chemicals called pyrrolizidine alkaloids, or PAs, that can also be absorbed through the skin. Talk to your doctor before using comfrey as an herbal medicine.
Identification and Dosing
Comfrey is commonly known as blackwort, gum plant, common comfrey, consolidae radix, slippery root, wallwort, Symphytum officinale and healing herb, among other names. According to the Natural Medicines Comprehensive Database, or NMCD, some products labeled as common comfrey may actually contain a more toxic species of comfrey called Symphytum asperum. Currently, there are no official dosing guidelines for comfrey. However, topical use of comfrey should not exceed 100 mcg per day of the PAs, warns Drugs.com.
Uses
Comfrey is taken as a tea for treating stomach ailments, ulcers, diarrhea, blood in the urine and heavy menstrual bleeding. It is also used for bronchitis, cough, chest pain or angina, painful breathing, and cancer. Some use comfrey as a gargle for inflammation of the gums and throat. Comfrey is applied topically for bruises, bone fractures, ulcers, wounds, arthritis, swollen veins or phlebitis, and gout.
Effectiveness
Comfrey may relieve pain and tenderness when applied to the skin for treating bruises, sprains and arthritis, reports the NMCD. There is not enough information to determine the effectiveness of comfrey for other conditions.
Considerations
According to the NMCD, comfrey is possibly safe when applied to unbroken skin in small amounts for fewer than 10 days. Comfrey is rated as likely unsafe when taken orally because the PAs can cause serious side effects, including liver injury, lung damage, and cancer, warns the NMCD. Comfrey should not be used on broken skin or in the presence of liver disease, says the NMCD. Avoid comfrey during pregnancy and lactation.
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