Not recommended for internal or limited topical use because of the content of hepatotoxic pyrrolizidine alkaloids
Historically daily doses of leaf ranged from 5 to 30 g
Bronchitis, bruises (topical use), cancer, cough (persistent), fractures (topical use), peptic ulcer, rheumatism, skin ulcers (topical use), sprains (topical use), wound healing (topical use), gastritis, ulcers, excessive menstrual flow, gargle for gum disease
Preliminary research suggests that when applied topically may improve pain & tenderness of bruises, as well as muscle and joint pain
FDA released advisory in 2001 recommending that all comfrey products be removed from market because of cases of hepatic veno-occlusive disease
abdominal distension, abdominal pain, anorexia, lethargy, liver enlargement, urine output decrease, veno-occlusive disease
Broken or damaged skin (potentially contains toxic unsaturated pyrrolizidine alkaloids)
Pregnancy & Lactation
Pregnancy Category: avoid use
Lactation: avoid use
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Mechanism of Action
Allantoin stimulates connective tissue & leukocyte proliferation
Water extract stimulates prostaglandin production in stomach