Comfrey leaves and roots have been used for many centuries for wound healing, inflammation, and other conditions, but these effects have not been confirmed in humans through clinical trials.
Cases of liver toxicity have been reported with use of comfrey. It has also been confused with foxglove, a poisonous plant, which has resulted in several cases of accidental poisoning.
Comfrey is a shrub growing in parts of Europe, Asia, and North America. While it may help with wounds and joint pain, studies warn against eating it due to a risk of liver damage and cancer.