Comfrey side-effects


What are the adverse effects of using comfrey as a medicinal plant?

flowers of comfrey
Closeup photo of some flowers of comfrey

Potential adverse effects derived from the use of comfrey are:

  • Liver disease: Its toxic principles accumulate and damage the liver (hepatotoxic). Externally, if too often used, it can cause liver damage. It can aggravate existing liver disease such as cirrhosis or hepatitis.

Animals fed with comfrey for 6 months have come to produce liver cancer, because it contains carcinogenic components (components that cause cancer).

  • Loss of appetite, abdominal pain, vomiting: It has been reported that the plant can have side effects related to digestive disorders.
  • Dermatitis: Comfrey can cause contact dermatitis or skin irritation by direct contact with the fresh plant.
  • Hypersensitivity: This plant can cause hypersensitivity because it is very hairy. It can cause irritation to mucous membranes or to skin.
  • Allergy: Some people may have allergy to comfrey.
  • Medicines: comfrey can interact with certain medicines, including some antidepressants.

* More information on comfrey contraindications.

Comfrey use in pregnancy and lactation

Comfrey treatments must not be used in pregnancy or lactation

Toxic alkaloids can cross the placental and breast barriers, reaching the fetus or the baby. NO treatment with comfrey (internally or externally) should be administered during pregnancy and lactation.

More information on comfrey.

This article was endorsed by Vicente Martínez Centelles - Founder of the web and director. Teacher of natural sciences, expert in plants, natural remedies and botanical photography.
Written by Editorial Botanical-online team in charge of content writing

5 February, 2022

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This material is for informational purposes only. In case of doubt, consult the doctor.
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