Symphytum officinale.  Comfrey, Knitbone, Cosolida, Blackwort, Nipbone Family: Boraginaceae   
S. tuberosum = Tuberous Comfrey.
S. X  uplandicum = Russian Comfrey.  


PART USED: Leaves- Upper surface dark-green, paler on the underside, obovate to lanceolate, 15-25 cm in length and 4-10 cm wide.
ODOR: None TASTE: Sweet and mucilaginous.
ACTIONS
GROUP: Herbs for trauma and recovery- Vulnerarys
1. Anti-inflammatory.[1,2] Anti-rheumatic.[1,2]
2. Demulcent.[1,2]
3. Antihemorrhagic.[1]
Topically- Vulnerary.[1,2]
INDICATIONS- Restricted internal use in Australia
1. Ulcers especially chronic varicose ulcers- local use also.
2. Peptic ulcers especially gastric. Gastric and duodenal ulcers.[1]
3. Chronic varicose ulcers. Crural ulcers.
4. Rheumatism.[1,2] Arthritis.[1] Sprains.[1,2]
5. Bruising.
6. Mastitis.
Topical- As poultice or formentation in Bruises, sprains, athlete's foot, crural ulcers and mastitis.[1] Varicose ulcer.
SPECIFIC INDICATIONS: Gastric ulcer.[1] Topically: Vaicose ulcer.[1]
COMBINATIONS
Similar to Comfrey root.
- Powdered leaf, use with Slippery Elm bark and Linseed for poultice.
- Topical treament of sprain, use with Jacobaea and Elder flower leaf.
PREPARATIONS   3X /day
Leaf  2-8 g,[1] or by infusion 1:20.[1,2]
Fluid extract 1:1 in 25% alcohol[4]  2-8 ml.[1,2]
Local-  Ointment  root , poultice  leaf
CONTRAINDICATIONS: Comfrey is not recommended for treatment of fractures if pins or plates are in use. Comfrey may cause pain if an I.U.D. is in use.

PART USED: Root- Collected in Spring or Autumn.  
TASTE: Mucilaginous  ODOR: None
ACTIONS
GROUP: Herbs for trauma and recovery- Vulnerarys
1. Vulnerary.[1,2]
2. Cicitrant (to heal with scar tissue).
3. Demulcent.[1,2]
4. Cell proliferant.[1]
5. Astringent.[1]
6. Antihemorrhagic.[1]
INDICATIONS- Restricted internal use in Australia
1. Gastric and duodenal ulcers.[1,2] Hematemesis.[1,2] Colitis.[1,2] Diarrhea. As a general demulcent.
2. Fractures hernia.
Topically- Ulcers,[1] wounds,[1] fractures,[1] hernia-[1] by application of fresh root preparation.[1]
SPECIFIC INDICATION: Gastric ulcer.[1] Topically- chronic varicose ulcer.[1]
COMBINATIONS
- Gastric ulcer, use with Meadowsweet and/or Marshmallow.
- Topical external application as an ointment, use with Marshmallow.
PREPARATIONS   3X /day
Dried root  2-8 g. 2-4 g,[1,2] or by decoction[1] 1:20.
Liquid extract  1:1 in 25% alcohol  2-4 ml.[1,3]
Liquid extract 1:2 in 25% alcohol.[4]
Local- Ointment of root 10-15% extract in usual type of ointment base.[1]


PART USED: Root and leaves  
ACTIONS
1. Demulcent.[3]
2. Astringent.[3]
3. Anti-inflammatory.[3]
4. Vulnerary.[3]
5. Anti-psoriatic.[3]
INDICATIONS- Restricted internal use in Australia.
1. Pulmonary complaints.[3]
2. Gastric sedative.[3]
3. Rheumatism and painful joints.[3]
4. Local- Ointment, oil, or poultice for psoriasis, eczema, ulcers and to promote wound healing.[3]

ORIGIN: Cultivated in Britain and USA.
HABITAT:
Damp places.
DESCRIPTION:
Leafy perennial, growing to 1 m in height. Leaves; large, bristly obovate or lanceolate. Stem; hollow and bristly. Flowers; bell like, occurring in spikes with white or mauve flowers.
References

Constituents

Research
The anti-inflammatory activity of extracts of Comfrey has been demonstrated in vitro and in vivo.[2,3] this may be due to rosmarinic acid, which has a similar effect.[2]
A herbal extract stimulated the release of a prostaglandin-like material from rat gastric mucosa, possibly explaining its usefulness as a gastric sedative.[3]
The pyrrolizidine alkaloids are hepatotoxic in animals.[4,5,6] Comfrey has been implicated in causing in one instance a case of hepatic veno-occlusive diseases after chronic use.[7] However in animal studies the alkaloids were poorly absorbed through the skin,[8] and since they do not seem to be present in commercial comfrey extracts,[9,10] toxicity does not appear to be a problem.[1] However it would be wise to avoid using fresh leaves in salads.[1]
Aqueous extracts of Comfrey leaves increase survival times of mice bearing spontaneous tumors, and decrease tumor growth,[11] and in an Ames test produced less mutants than the control,[12] suggesting that Comfrey may have antimutagenic activity.[1]
References

In vivo wound healing effects of Symphytum officinale L. leaves extract in different topical formulations.
Araújo LU, Reis PG, Barbosa LC, Saúde-Guimarães DA, Grabe-Guimarães A, Mosqueira VC, Carneiro CM, Silva-Barcellos NM.
Abstract
The present work evaluates wound healing activity of leaves extracts of Symphytum officinale L. (comfrey) incorporated in three pharmaceutical formulations. Wound healing activity of comfrey was determined by qualitative and quantitative histological analysis of open wound in rat model, using allantoin as positive control. Three topical formulations, carbomer gel, glycero-alcoholic solution and O/W emulsion (soft lotion) were compared. The histological analysis of the healing process shows significant differences in treatment, particularly on its intensity and rate. The results indicate that emulsion containing both extracts, commercial and prepared, induced the largest and furthest repair of damaged tissue. This could be evidenced from day 3 to 28 by increase in collagen deposition from 40% to 240% and reduction on cellular inflammatory infiltrate from 3% to 46%. However, 8% prepared extract in emulsion presented the best efficacy. This work clearly demonstrates that comfrey leaves have a wound healing activity. The O/W emulsion showed to be the vehicle most effective to induce healing activity, particularly with extracts obtained from comfrey leaves collected in Minas Gerais state in Brazil. It shows the best efficacy to control the inflammatory process and to induce collagen deposition at 8% concentration.
PMID: 22570943  Pharmazie. 2012 Apr;67(4):355-60. ncbi.nlm.nih.gov

Comfrey: A Clinical Overview
Christiane Staiger*
Abstract
Comfrey has a centuries-old tradition as a medicinal plant. Today, multiple randomized controlled trials have demonstrated the efficacy and safety of comfrey preparations for the topical treatment of pain, inflammation and swelling of muscles and joints in degenerative arthritis, acute myalgia in the back, sprains, contusions and strains after sports injuries and accidents, also in children aged 3 or 4 and over. This paper provides information on clinical trials and non-interventional studies published on comfrey to date and further literature, substantiating the fact that topical comfrey preparations are a valuable therapy option for the treatment of painful muscle and joint complaints.
Phytother Res. 2012 Oct; 26(10): 1441–1448. Published online 2012 Feb 23. doi: 10.1002/ptr.4612  PMCID: PMC3491633 ncbi.nlm.nih.gov Full article

Absence of mutagenic effects of a particular Symphytum officinale L. liquid extract in the bacterial reverse mutation assay.
Benedek B, Ziegler A, Ottersbach P.
Abstract
Comfrey (Symphytum officinale L.) root is traditionally used for the topical treatment of contusions, strains and sprains. Besides allantoin and rosmarinic acid, which are discussed as pharmacologically active principles, the drug contains pyrrolizidine alkaloids (PAs) known for their hepatotoxic, carcinogenic and mutagenic properties. The topical herbal medicinal products Kytta-Salbe f and Kytta-Plasma f contain a PA-free liquid extract from comfrey root as active substance. The aim of this study was to demonstrate the absence of genotoxic effects of this special extract in the bacterial reverse mutation assay (Ames test). Briefly, comfrey root liquid extract was investigated for its ability to induce gene mutations in Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537 with and without metabolic activation using the mammalian microsomal fraction S9 mix. Reference mutagens were used to check the validity of the experiments. Comfrey root fluid extract showed no biologically relevant increases in revertant colony numbers of any of the five tester strains, neither in the presence nor in the absence of metabolic activation. In conclusion, the comfrey root fluid extract contained in Kytta-Salbe f and Kytta-Plasma f was not mutagenic in the bacterial reverse mutation assay.
PMID: 19827020 DOI: 10.1002/ptr.3000 Phytother Res. 2010 Mar;24(3):466-8. doi: 10.1002/ptr.3000. ncbi.nlm.nih.gov

Comfrey (Symphytum Officinale. l.) and Experimental Hepatic Carcinogenesis: A Short-term Carcinogenesis Model Study
Maria Fernanda Pereira Lavieri Gomes, Cristina de Oliveira Massoco, José Guilherme Xavier, and Leoni Villano Bonamin
Abstract
Comfrey or Symphytum officinale (L.) (Boraginaceae) is a very popular plant used for therapeutic purposes. Since the 1980s, its effects have been studied in long-term carcinogenesis studies, in which Comfrey extract is administered at high doses during several months and the neoplastic hepatic lesions are evaluated. However, the literature on this topic is very poor considering the studies performed under short-term carcinogenesis protocols, such as the ‘resistant hepatocyte model’ (RHM). In these studies, it is possible to observe easily the phenomena related to the early phases of tumor development, since pre-neoplastic lesions (PNLs) rise in about 1–2 months of chemical induction. Herein, the effects of chronic oral treatment of rats with 10% Comfrey ethanolic extract were evaluated in a RHM. Wistar rats were sequentially treated with N-nitrosodiethylamine (ip) and 2-acetilaminofluorene (po), and submitted to hepatectomy to induce carcinogenesis promotion. Macroscopic/microscopic quantitative analysis of PNL was performed. Non-parametric statistical tests (Mann–Whitney and ?2) were used, and the level of significance was set at P = 0.05. Comfrey treatment reduced the number of pre-neoplastic macroscopic lesions up to 1 mm (P = 0.05), the percentage of oval cells (P = 0.0001) and mitotic figures (P = 0.007), as well as the number of Proliferating Cell Nuclear Antigen (PCNA) positive cells (P = 0.0001) and acidophilic pre-neoplastic nodules (P = 0.05). On the other hand, the percentage of cells presenting megalocytosis (P = 0.0001) and vacuolar degeneration (P = 0.0001) was increased. Scores of fibrosis, glycogen stores and the number of nucleolus organizing regions were not altered. The study indicated that oral treatment of rats with 10% Comfrey alcoholic extract reduced cell proliferation in this model.
Evid Based Complement Alternat Med. 2010 Jun; 7(2): 197–202.
Published online 2007 Dec 26. doi: 10.1093/ecam/nem172   PMCID: PMC2862927 ncbi.nlm.nih.gov