Erica M. Hollis
Medicinal Uses of Comfrey (Symphytum species) Past, Present and Future: A literature review and extended monograph tracing the historical uses of the herb through to the present day in order to assess its future potential
A literature review of ancient and modern herbals, research papers and other commentary on medicinal use of comfrey was undertaken to establish the traditional background to modern use.
In the latter half of C20th, discovery of pyrrolizidine alkaloids in Symphytum species, and high-profile reporting of four cases of liver damage attributed to ingestion of comfrey products, raised doubts over its safety. Other authors have addressed these safety concerns in detail, but there appeared to be less effort on establishing comfrey’s historical therapeutic background, the basic justification for modern use.
This dissertation set out to investigate what parts of the plant had been used, how they were prepared, what diseases or conditions they were prescribed for and how comfrey was viewed in terms of traditional Western energetics. To give a modern perspective on the latter, a database of herb tasting results was also sampled.
Early on, it became clear that identification of which species had been used medicinally was frequently misunderstood, so the research was widened to investigate this issue.
Although the literature reviewed was mainly restricted to readily obtainable, English-language texts, reasonable evidence of comfrey’s key therapeutic actions was obtained. However it became apparent that: modern and traditional methods of preparation differed; few researchers understood how to identify the medicinal species and non-herbalist writers considered various different species equally therapeutic.
In conclusion, while there is sufficient evidence to continue using S. officinale for its traditional therapeutic purposes, far more care needs to be taken over species identification.
Future research into growing conditions and analysis of traditional preparations such as syrups might bring additional leverage to prevent it being banned for internal use in the UK, as has happened in several other countries. Restricting supply of comfrey-containing medicines to qualified herbal practitioners, who understand its history and relevant therapeutic considerations, could be a reasonable alternative.
