Comfrey (Herb/Suppl)

Brand and Other Names:black root, blackwort, more...bruisewort, common comfrey, gum plant, healing herb, knitbone, prickley comfrey, salsify, slippery root, symphytum officinale, wallwort

Suggested Dosing

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


Suggested Uses

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


Adverse Effects

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

Pregnancy Categories

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.



Metabolism: N/A

Excretion: N/A

Mechanism of Action

Allantoin stimulates connective tissue & leukocyte proliferation

Water extract stimulates prostaglandin production in stomach

Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.