Comfrey is of the borage family and is a wide type of plant that has pretty pink, white,blue, even yellow flowers. Years ago people used to use this internally for lung disorders, including tuberculosis. Many people  view comfrey as some type of a wonder drug.There's no end as to what this herb can be used for.

Comfrey has a high content of allantoin, which is an agent which promotes cell proliferation. Quantities of tannin and mucilage are also present. The root is more toxic than the leaves.

ALL comfrey species have been found to contain hepatotoxic pyrrolizidine alkaloids that are highly toxic to the liver and can cause death. Pyrrolizidine alkaloids are poisonous compounds and is also absorbed through the skin, and harmful amounts may build up in the body

Comfrey taken internally as a tea or in salads has been reported to cause liver failure. One of the most common causes of veno-occlusive disease is ingestion of plant materials that contain hepatotoxic PA's.

In July 2001, the U.S. Food and Drug Administration required that dietary supplement manufacturers immediately remove all oral comfrey products from the market. The United Kingdom, Australia, Canada, and Germany also have banned the sale of oral products containing comfrey.

We herbalists can do better than that.There are plenty of other herbs we can use instead.