Comfrey is a potent tissue healer of the skin, connective tissues and bone (2). It is now recommended for external use only, as it contains potentially toxic constituents called pyrrolizidine alkaloids (PAs) (3). See the section on safety (below).

Comfrey is a primary first aid remedy for wounds, cuts, abrasions, burns, scalds, sunburn, skin irritations and rashes (4,5). It has a soothing and cooling effect. The cell-healing action of some of the constituents, notably allantoin which rapidly moves through the tissues, speeds up wound healing and reduces the production of scar tissue (6).

There is a wealth of clinical research demonstrating the efficacy and safety of comfrey preparations for topical treatment of painful muscle and joint complaints including pain, inflammation and swelling of muscles and joints in degenerative arthritis; acute myalgia (muscle pain); sprains, contusions and strains after sports injuries and accidents (7,8).

Comfrey is cooling, moistening, and slightly constricting (9,10,11). Energetically and emotionally, comfrey relates to the base chakra; where energy is stored (12). Comfrey is for those who lack structure and form in their lives, who need to develop a solid base, to give a sense of order where chaos is felt (12). Comfrey is a powerful healer of raw and sensitive emotional wounds and trauma, providing a soothing and grounding protective layer while the person heals (12).  Comfrey also confers determination, cohesiveness, and the ability to fuse back together what has come apart, while encouraging growth and change (2,13).

I can see no evidence for the classic proving of the homeopathic use of comfrey and I guess it is just a commercial enterprise. I vote to exclude this sentence.

Comfrey has a long history of use in healing wounds, injured tissues, and broken bones; and many of the common names allude to these virtues (14). Parkinson recommended that the fresh roots were “bruised, beaten small and laid on leather” to be applied externally to broken bones, fresh wounds, gout, painful joints, ulcers, and gangrene (11). A decoction of the root was used externally for mastitis and bleeding haemorrhoids, while the internal applications were for ailments of the lungs to help expectorate mucus and heal ulcers in those who are coughing up blood (11).

The earlier traditions of internal use largely stemmed from the effect of the mucilaginous agents on mucous tissues of the lungs and digestive tract (15). A strong decoction of the root, drunk ad libitum, was used for pneumonia, quinsy, whooping cough, to relieve breathing difficulty and to aid expectoration, especially in cases of bleeding in the lungs (14,16). Comfrey root, boiled in water, or made into a wine or syrup was used for diarrhoea, dysentery, bronchial irritation, coughs, haemoptysis, leucorrhoea, female debility, and passive haemorrhages from the bowels, kidneys, or womb (15). These were taken in doses of 1 to 4 fluid ounces (30–100ml), 2–3 times a day. (15).

The young leaves were eaten as a green vegetable and used to flavour cakes, while the roots were used together with chicory and dandelion root as a coffee alternative (14).

It should be noted that since the discovery of pyrrolizidine alkaloids, constituents with known toxicity risks, that can cause veno-occlusive liver disease in susceptible individuals, many of the traditional herbal uses of the comfrey have come into question (11) The delayed nature of this potential toxicity means that it is unlikely to have been spotted in earlier practice and now we cannot exclude the possibility that this happened. See the section on safety below.

Skin

The therapeutic properties of comfrey are based on its tissue healing, astringent, anti-inflammatory, and analgesic effects when applied directly to the skin (7). Due to the PA content of comfrey and the associated potential hepatotoxicity, the safest means of taking this herb is via external application. The skin absorption of PAs is low, while the other therapeutic constituents are freely absorbed (3).

Comfrey stimulates granulation and tissue regeneration and prevents scar tissue formation, making it an excellent remedy for any type of skin damage (7). Allantoin and rosmarinic acid are implicated in the pharmacodynamic effects of comfrey (7). Allantoin is a potent cell-proliferator, which stimulates the growth of healthy tissue, speeds wound-healing and reduces scar formation (6,17). Rosmarinic acid has anti-inflammatory, anti-viral and anti-bacterial activity (3,17). In addition to the action of allantoin and the phenols, the mucilaginous polysaccharides have a local anti-inflammatory and soothing action (18). There are also high levels of astringent tannins that will help heal surface damage. This makes comfrey ideal for topical applications to the skin for bruises, swellings, irritable skin lesions, wounds, ulcers, insect bites, eczema and psoriasis (10,18,19). Allantoin is highly soluble in hot water, somewhat soluble in oil, and only slightly soluble in alcohol extracts (17). For this reason, comfrey works well as a poultice, compress, soak or wash for wounds, external ulcers, burns, eczema, acne, psoriasis and chronic varicose ulcers (2,6). Human clinical and observational studies have identified the efficacy of external comfrey preparation for acne, psoriasis, atopic dermatitis and venous leg ulcers (21).

Musculoskeletal

Bone

Comfrey is one of the best herbs to support bone healing from fractures and breaks, due to the combination of the minerals, the healing properties of allantoin, and the anti-inflammatory action. Allantoin is a remarkable cell proliferator that stimulates the production of collagen, connective tissue, cartilage and bone (4).

Soft-tissue

The anti-inflammatory, analgesic and healing properties of comfrey can be applied to heal soft-tissue injuries such as sprains, bruises, pulled muscles, ligament strains; and myalgia (muscle pain) (19,33,34). The topical application of comfrey has been shown to have an anti-inflammatory and analgesic action which improves pain and functional movement in acute myalgia (22). In acute ankle sprains, comfrey ointment has been shown to reduce pain and ankle oedema, and improve ankle mobility (23), with a superior analgesic effect to diclofenac (24,25).

Joints

Comfrey reduces inflammation and pain in joint conditions such as osteoarthritis, degenerative arthritis and gout (19,33,34). In addition to the actions of allantoin, phenols and mucilage, the silica in comfrey affects both soft and firm structures in the human body, having a firming effect on soft connective tissue and strengthening and stabilising joints and ligaments (13). Comfrey root extract ointment has been clinically demonstrated to reduce pain, improve mobility and increase quality of life in knee osteoarthritis (26). Additionally, two observational studies identified that two weeks of topical treatment with comfrey root preparations reduced joint pain by 50% and completely eliminated morning stiffness in osteoarthritis (26). In addition to working well as an ointment for musculoskeletal conditions, comfrey works well as a warm compress, as the mucilage retains the heat and allows the heat to penetrate the tissues more progressively (18).

Gastrointestinal

Due to concerns about hepatotoxicity the internal use of comfrey is no longer recommended. However before these potential long-term risks were identified it was used in the gastrointestinal tract for its wound-healing, analgesic, astringent and soothing effects and some practitioners still reserve it for the short term only (3). The mucilaginous polysaccharides produce a mucous coating which soothes and protects exposed or irritated surfaces of the gastrointestinal tract (18). The astringent tannins can stop bleeding and protect the surface membranes against inflammation and infection (4). Comfrey has therefore been used in the treatment of gastric and duodenal ulcers, gastric reflux, oesophagitis, ulcerative colitis and hiatus hernia (6,18).

Herbal alternatives to comfrey to support mucous membrane healing and treat gastric ulcers, gastritis and gastrointestinal inflammations include slippery elm bark (Ulmus fulva), marshmallow root (Althaea officinalis), liquorice (Glycyrrhiza glabra), plantain (Plantago lanceolata) and meadowsweet (Filipendula ulmaria) (4,6).

A critical scoping review in 2013 evaluated the clinical evidence to support the external uses of comfrey (21). The authors concluded that there is robust evidence of benefit for ankle distortions (sprains), back pain, abrasion wounds and osteoarthritis (21).

Wound-healing

Barna carried out a randomised-controlled, double-blind clinical study on 278 patients with fresh skin abrasions. Topical application of a comfrey ointment (10% extract) was compared to a lower dose, reference preparation (1% extract). After 2–3 days there was a significantly faster reduction in the wound area with the 10% extract, and a complete healing time that was three days faster than the 1% extract. The authors concluded that comfrey ointment extract can contribute to significant wound-healing effects (20).

Muscle pain/myalgia

Kucera et al. assessed the effectiveness of two strengths of topical comfrey cream (10% vs 1%) in 215 patients with myalgia. Participants in both groups applied 2–3 g of cream three times per day, for 8–10 days to their affected pain area. Pain in motion, pain at rest, and pain on palpation all decreased in both groups, and this effect was significantly greater for the 10% cream. The authors concluded that the study confirms the anti-inflammatory and analgesic effects of topical comfrey application for muscle pain (22).

Osteoarthritis

Grube et al. carried out a randomis ed, double‐blind, placebo-controlled trial of 220 patients with painful osteoarthritic knee. Three times a day for 21 days the patients applied 2 g comfrey root cream (35% of a 1:2 extract, equivalent to 17.5 g comfrey root per 100 g) or placebo cream. Pain at rest and during movement decreased significantly more in the comfrey group (54.7%) compared to the placebo (10.7%). Pain, stiffness and function symptoms were reduced by 58.0% in the comfrey group, which was significantly greater than the placebo (14.1%). Knee mobility and quality of life significantly increased in the comfrey group. The authors concluded that comfrey root extract ointment is well suited for the treatment of knee osteoarthritis by reducing pain, improving mobility and increasing quality of life (26).

Sprains

142 patients with a unilateral acute ankle sprain took part in a double-blind, randomised, placebo-controlled study (23). A comfrey extract ointment (35% of a 1:2 extract, equivalent to 17.5 g comfrey root per 100 g) or placebo, was applied at 2 g, four times per day, for 7—9 days. The comfrey treatment significantly reduced pain and ankle oedema, and significantly improved ankle mobility compared to the placebo (23).

A randomised, parallel-group study enrolled 164 patients with an acute, unilateral ankle sprain (24). Four times per day, for 7 days they applied 2 g of either comfrey ointment (35% 1:2 extract, equivalent to 17.5 g comfrey root per 100 g), or diclofenac gel. The improvement in tenderness to pressure was superior in the comfrey group. Pain at rest decreased by 92% and 85% in the comfrey and diclofenac groups, respectively, and pain during movement decreased by 83% and 72% for the comfrey and diclofenac groups, respectively. There was a slightly greater, but not significantly different reduction in pain in the comfrey group, meaning the comfrey had a comparable analgesic effect to the diclofenac (24). A later study re-evaluated the data and concluded that comfrey ointment was statistically superior to diclofenac (25).

Comfrey is used as an organic fertiliser by soaking the leaves in water to make a liquid feed for nourishing poor-quality soil   (27,28). The fresh leaves also speed up composting and can be used as mulch around other plants in the growing season (27). However, using comfrey in such a way can increase the PA content of plants in the vicinity via horizontal transfer (29). The use of comfrey in composting and as a fertiliser is, therefore, only appropriate for ornamental gardening.

The native distribution is across Europe and UK, and is widely naturalised across North America, parts of South America and temperate Asia (41,42). Comfrey often forms extensive colonies and can be found in wetland areas such as damp grassland, riverbanks, streambanks, canal sides, ditches, bogs, marshes, swamps, peatlands and damp road verges (39,40,42).

Comfrey is not listed by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), therefore is not subject to any trading controls (44).

Comfrey has not been ranked by Nature Serve since it is common and well distributed across North America, and does not appear on the U.S. Endangered Species act (45). Comfrey is not on the United Plant Savers “to watch” list (46).

The International Union for Conservation of Nature (IUCN) globally assessed Symphytum officinale in 2012 and lists it as “Least Concern”. They state that the species is widely distributed and abundant in many parts of Europe, with stable subpopulations, and there are currently no known threats to this species (42).

The Vascular Plant, Red Data List for Great Britain lists comfrey as least Concern (LC),  meaning it has been evaluated against the criteria and does not qualify as critically endangered, endangered, vulnerable or near threatened (43).

Habitat loss and over-harvesting from the wild are two of the biggest threats faced by medicinal plant species. There are an increasing number of well-known herbal medicines at risk of extinction. We must, therefore, ensure that we source our medicines with sustainability in mind.

The herb supplement industry is growing at a rapid rate and until recent years a vast majority of medicinal plant produce in global trade was of unknown origin. There are some very real and urgent issues surrounding sustainability in the herb industry. These include environmental factors that affect the medicinal viability of herbs, the safety of the habitats that they are taken from, as well as the welfare of workers in the trade.

The botanical supply chain efforts for improved visibility (transparency and traceability) into verifiably sustainable production sites around the world is now certificated through the emergence of credible international voluntary sustainability standards (VSS).

Read our article on Herbal quality and safety: What to know before you buy and Sustainable sourcing of herbs to learn more about what to look for and questions to ask suppliers about sustainability.

Herbal medicines are often very safe to take; however, their safety and efficacy can be jeopardised by quality issues. So, it is important to buy herbal medicines from a reputable supplier, from sources known to test their herbs to ensure there is no contamination, adulteration or substitution with incorrect plant matter, as well as ensuring that recognised marker compounds are at appropriate levels in the herbs.

Some important quality assurances to look for are certified organic labelling, the correct scientific/botanical name, and the availability of information from the supplier about ingredient origins. A supplier should be able to tell you where the herbs have come from, what contaminants are not in the herb, and what the primary compounds are.

Propagation can be either by division of the roots in spring, root cuttings in early winter, or seed sown in pots in a cold frame in autumn or spring, though the germination of seeds is slow and erratic (27,28). Comfrey grows well in moderately fertile, moist soil in sun or partial shade, though it can grow vigorous once established, with the potential to become a nuisance (28).

Healing balm

This anti-inflammatory and healing balm is ideal for broken bones, sprains and strains, muscles and joint aches.

Ingredients

• 75 ml comfrey leaves and root infused oil – Find out how to make infused oils on our page How to make herbal oils.
• 25 ml arnica-infused oil
• 10 g beeswax
• 10 drops wintergreen essential oil
• 5 drops rosemary essential oil

Method

• Heat the infused oil and beeswax in a bain-marie, until the wax has melted.
• Remove from the heat and allow to cool for 5–10 minutes before stirring in the essential oils.
• Pour into a sterilised jar and allow to cool before adding the lid.
• Label and store in a cool, dark place for use within a year.
• Massage into the area required three times per day.

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