General poisoning notes:

Common comfrey (Symphytum officinale) is an introduced and naturalized herb found on damp roadsides and waste places in many parts of Canada. This plant contains several pyrrolizidine alkaloids, which cause veno-occlusive symptoms, liver cirrhosis, and death. Humans have been affected after ingesting herbal teas and medicines. Rats have developed hepatocellular tumors after ingesting the alkaloid symphytine, found in common comfrey. Canadian health officials have sought to ban sale of some comfrey products. Animals normally do not ingest the plant because of the bristly hairs. Topical herbal preparations are not considered toxic because the alkaloids do not reach the liver (Steuart 1987, Huxtable 1989, Ridker and McDermott 1989). Russian comfrey (Symphytum X uplandicum Nym. [synonymy: Symphytum peregrinum Ledeb.]) has been grown in Canada in Lethbridge, Alta., and Vancouver Island, as a trial forage crop for livestock, but it was not found to be suitable. This plant may be available from some nursery seed suppliers. Russian comfrey also contains pyrrolizidine alkaloids and should not be taken internally as a herb remedy.

References:

Huxtable, R. J. 1989. Human health implications of pyrrolizidine alkaloids and herbs containing them. Pages 41-86 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Ridker, P. M., McDermott, W. V. 1989. Comfrey herb tea and hepatic veno-occlusive disease. Lancet, 1989: 657-658.

Steuart, G. 1987. Growing alkaloid-free comfrey. Herbs Spices Med. Plants, 5(4): 9.

Nomenclature:

Scientific Name: Symphytum officinale L.

Vernacular name(s): common comfrey

Scientific family name: Boraginaceae

Vernacular family name: borage

References:

Agriculture Quebec. 1975. Noms des maladies des plantes du Canada/ Names of plant diseases in Canada. , Quebec City, Que., Canada. 288 pp.

Alex, J. F., Cayouette, R., Mulligan, G. A. 1980. Common and botanical names of weeds in Canada/Noms populaire et scientifiques des plantes nuisibles du Canada. Revised. Agric. Can. Publ., Ottawa, Ont., Canada. 132 pp.

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Scoggan, H. J. 1978, 1979. The flora of Canada. Nat. Mus. Nat. Sci. (Ottawa) Publ. Bot. 7(1)-7(4). 1711 pp.

Van Wijk, H. L. 1911. A dictionary of plant names. Martinus Nijhoff, The Hague, The Netherlands. 1444 pp.

Victorin, M. 1964. Flore Laurentienne. 2nd ed. Univ. Montreal, Montreal, Que., Canada. 952 pp.

Geographic Information

Alberta
British Columbia
New Brunswick
Newfoundland
Ontario
Quebec

References:

Bailey, L. H., Bailey, E. Z. 1976. Hortus third. Revised. MacMillan, New York, N.Y., USA. 1290 pp.

Boivin, B. 1966, 1967. Énumération des plantes du Canada. Provencheria 6. Nat. Can. (Que.) 93: 253-274; 371-437; 583-646; 989-1063. 94: 131-157; 471-528; 625-655.

Notes on Poisonous plant parts:

The roots have greater concentrations of pyrrolizidine alkaloids than the leaves. Animals do not commonly ingest the plants because of the bristly leaves (Cooper and Johnson 1984, Huxtable 1989).

Toxic parts:

all parts
leaves
roots

References:

Cooper, M. R., Johnson, A. W. 1984. Poisonous plants in Britain and their effects on animals and man. Her Majesty's Stationery Office, London, England. 305 pp.

Huxtable, R. J. 1989. Human health implications of pyrrolizidine alkaloids and herbs containing them. Pages 41-86 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Notes on Toxic plant chemicals:

Common comfrey contains several pyrrolizidine alkaloids, including echimidine, heliosupine, lycopsamine, and symphytine. Alkaloids were found in the plant totalling 0.07% dry weight in roots and 0.062% in dry leaves, and 0.006% in fresh leaves. Two alkaloids found in common comfrey were shown to cause liver and bladder tumors in rats; the roots have more toxins the than leaves. Some commercial products of roots and leaves sold as herbal teas and medicinal preparations have a total alkaloidal concentration of 270 mg/kg (leaves) and 2900 mg/kg (roots). Ingesting a cup of tea made from the roots may contain 8.5 mg of alkaloid, which is 26 mg per cup if the gelatinous residue is consumed. [Huxtable 1989].

Toxic plant chemicals:

echimidine
heliosupine
lycopsamine

References:

Huxtable, R. J. 1989. Human health implications of pyrrolizidine alkaloids and herbs containing them. Pages 41-86 in Cheeke, P. R., ed. Toxicants of plant origin. Vol. I. Alkaloids. CRC Press, Inc., Boca Raton, Fla., USA. 335 pp.

Animals/Human Poisoning:

Note: When an animal is listed without additional information, the literature (as of 1993) contained no detailed explanation.

Humans

General symptoms of poisoning:

ascites
liver, cirrhosis of

Notes on poisoning:

Ingesting pyrrolizidine alkaloids for several months leads to veno-occlusive problems and severe portal hypertension, which can lead to cirrhosis of the liver and death. Symptoms include ascites, edema, and reduced urinary output. Children are more susceptible than adults. In two cases, one women was estimated to consume at least 85 mg of pyrrolizidine alkaloids from a herbal leaf preparation over 6 months; another woman consumed 512 mg over 6 months (comfrey-pepsin preparation) (Huxtable 1990). Ridker and McDermott (1989) note that pulmonary endothelial hyperplasia can also occur from direct exposure to these alkaloids. Rats have developed hepatocellular tumors because of the alkaloid symphytine.

References:

Ridker, P. M., McDermott, W. V. 1989. Comfrey herb tea and hepatic veno-occlusive disease. Lancet, 1989: 657-658.

Information Source: ©Canadian Poisonous Plants Information System, Canadian Biodiversity Information Facility.