Comfrey is used as a tea for upset stomach, ulcers, heavy menstrual periods, diarrhea, bloody urine, persistent cough, painful breathing (pleuritis), bronchitis, cancer, and chest pain (angina). It is also used as a gargle for gum disease and sore throat.
Comfrey is applied to the skin for ulcers, wounds, joint inflammation, bruises, rheumatoid arthritis, swollen veins (phlebitis), gout, and fractures.