Comfrey (Symphytum officinale, oral)

Tier 4 — risky / avoid · Hepatotoxicity · Pyrrolizidine alkaloids

Contains toxic compounds called pyrrolizidine alkaloids that cause liver vein blockage disease, a serious and potentially fatal condition. FDA, European, and Australian authorities all advise against oral use. Multiple cases of liver failure have been reported. Topical application for musculoskeletal pain is the only acceptable use.

Dose: AVOID oral use entirely — topical application only for musculoskeletal pain