Comfrey

Purported Benefits, Side Effects & More
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This information describes the common uses of Comfrey, how it works, and its possible side effects.
Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

Although comfrey has been used historically for various conditions, cases of liver toxicity have been reported.

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.

What are the potential uses and benefits?

  • To treat bronchitis
    There is no scientific evidence to support this claim.
  • To treat pain
    A review of herbal medicine for low back pain did not find sufficient evidence for topical use of comfrey.
  • To treat cancer
    This claim is not backed by research.
  • To treat peptic ulcers
    There is no scientific evidence to support this.
  • To improve wound healing
    Lab studies show that comfrey leaves have wound healing effects, but human data are lacking.

What are the side effects?

Liver damage

What else do I need to know?

Patient Warnings:

  • In 2001 the FDA, along with the Center for Food Safety and Applied Nutrition, advised all dietary supplement manufacturers to remove products containing comfrey from the market.
  • Comfrey contains compounds that are toxic to the liver and animal experiments suggest it can cause liver cancer.
  • Comfrey has been confused with foxglove, a poisonous plant with similar leaves. Several cases of accidental ingestion of what was thought to be comfrey herbal tea occurred, resulting in poisoning and death in one case.