Comfrey (Symphytum officinale) is a member of the Boraginaceae family with leaf and root parts being used for medicinal purposes (Terra, 1998). The plant has attracted some controversy due to published research that has found that long-term ingestion of comfrey root was shown to cause liver damage (Mattocks, 1980).
Comfrey contains allontoin, mucilage, tannins, starch, inulin, traces of oil and liver-toxic pyrilizidine alkaloids which in animal studies have shown to cause liver disease.
Traditionally, comfrey was indicated for internal and external bleeding, broken bones, internal bleeding, lung problems, and digestive complaints with outstanding results due to its ability to increase cell proliferation (Terra, 1998).
Research on animal studies has provided evidence that comfrey damages rats’ livers when applied internally. As a result the FDA in 2001 requested comfrey be taken off the market.
Lewis (2001) states, “While information is generally lacking to establish a cause-effect relationship between comfrey ingestion and observed adverse effects in humans, the adverse effects that have been seen are entirely consistent with the known effects of comfrey ingestion described in the scientific literature” (Lewis, 2001).
The FDA’s ruling only applies to comfrey products designed for internal use, and not to the external use of comfrey such as ointment or salve. Special caution is advised when applying comfrey to open wounds.
Externally, comfrey is used for sprains, strains and torn ligaments, muscles, and tendons.
Recent studies published in Germany (Barna, et al., 2007) confirm comfrey’s ability to speed the healing of wounds when used externally. Another study that compared comfrey
ointment to a placebo for osteoarthritis has found comfrey to be superior to a placebo and effective in reducing pain, increasing the mobility of affected joints, and improving
quality of life (Grube, et al., 2007). Positive result research continues in the use of comfrey externally as a pain reliever and wound healer.
At the time of writing this article, there are no well known drug interactions with comfrey. According to Terra (1998), pregnant women, developing fetuses and infants seem to be vulnerable to pyrilizidine alkanoids, therefore comfrey is not recommended to these groups.
Barna, M., Kucera, A., Hladícova, M., Kucera, M. (2007). Wound healing effects of a
Symphytum herb extract cream (Symphytum x uplandicum): results of a randomized, controlled double-blind study. Wien Med Wochenschr, 157(21-22), 569-574. Abstract retrieved June 2, 2008, from PubMed database.
Grube, B., Grünwald, J., Krug, L., Staiger, C. (January, 2007). Efficacy of a comfrey root
(Symphyti offic. radix) extract ointment in the treatment of patients with painful
osteoarthritis of the knee: results of a double-blind, randomised, bicenter, placebo-controlled trial. Phytomedicine, 14(1), 2-10. Epub 2006 Dec 13. Abstract retrieved June 2, 2008, from PubMed database.
Lewis, C. (July 6, 2001). FDA advises dietary supplement manufacturers to remove
comfrey products from the market (FDA memo). Retrieved June 2, 2008, from
Mattocks A. R. (November 22, 1980). Toxic pyrrolizidine alkaloids in comfrey
[Electronic version]. Lancet, (2)82040, 1136-1137.
Terra, M. (1998). The way of Herbs. New York, NY: Pocket Books