Comfrey’s old name of knitbone refers to its strong healing action for broken bones. It will also knit flesh together, speeding the healing of wounds. Applied as a poultice or ointment, it can be used to treat bruises, dislocations and sprains. Despite much controversy, comfrey is safe if correct guidelines are followed.
Boraginaceae Borage family
Description: A lush, hairy, fast-growing plant with yellowish-cream or dull purple flowers, and a winged stem.
Habitat: Moist, marshy places.
Distribution: Common in the southern UK, but absent from parts of Scotland, Wales and Ireland. Native through Europe to Siberia. Introduced to North America and other temperate regions.
Related species: There are a number of species found in the British Isles, both natives and garden escapes. They can all be used externally, but only Symphytum officinale should be taken internally. Russian comfrey (S. x uplandicum) is common on drier ground, and is a hybrid between common comfrey (S. officinale) and rough comfrey (S. asperum). Tuberous comfrey (S. tuberosum) is native, with pale yellowish-cream flowers. White comfrey (S. orientale) has pure white flowers, while creeping comfrey (S. grandiflorum) has reddish flowers, which fade to yellowish-cream. Because comfreys hybridise, it can be difficult to tell them apart.
Parts used: Leaves, root.
Comfrey has a long history of use for its healing and anti-inflammatory effects on bone fractures, arthritis, inflamed joints, cuts, wounds and other injuries.
This herb had such a reputation for repairing tissue that it became popular for less virtuous brides to bathe in comfrey before their wedding day to restore their virginity!
Comfrey’s scientific and common names both refer to its healing qualities. Symphytum is from the Greek symphyo, make grow together, and phyton, plant; ‘comfrey’ is said to be from the Roman word conferre, join together.
In addition to medicinal benefits, comfrey is often grown as a fodder plant for animals, as a fertiliser and to add to compost. The most commonly grown comfrey for these purposes is Bocking 14, a sterile clone of Russian comfrey (S. x uplandicum).
Use comfrey for …
In the past, comfrey was widely used for healing ulceration in the digestive tract, as it is mucilaginous and soothing as well as healing. It was also used for bronchitis and other chest complaints, to soothe the irritation and promote expectoration of mucus.
Today, other herbs tend to be preferred for these conditions, owing to the possible dangers of the pyrrolizidine alkaloids contained in comfrey – see box on page 40. Comfrey nonetheless remains valuable as one of the best herbs for healing broken bones, snapped tendons, sprains, strains and bruises.
Once a bone has been set by a qualified person, apply a fresh comfrey poultice. If the fracture is in plaster, take the comfrey up to the edges of the plaster. In addition, use homeopathic comfrey (Symphytum 6x) internally as directed by a homeopath, or – as long as you are not pregnant or breastfeeding – you can drink a couple of cups of comfrey leaf tea a day until the bone heals. Use a leaf or half a large leaf per cup of tea, infusing for 5 minutes.
Comfrey can also be applied to varicose veins, as a poultice. For wounds and ulcers that are open, place mashed comfrey on the skin around the affected part. Comfrey can help heal old wounds such as surgical scars, being applied as a fresh poultice or using the infused oil or ointment. It is also effective on bruises and other injuries to the muscles, ligaments and tendons.
Comfrey’s powerful healing effects are partly explained by its allantoin content. This chemical stimulates cell proliferation, which speeds up the healing process, and is also an anti-inflammatory that supports the immune system.
Comfrey is so good at ‘knitting’ that it must not be used on broken bones until they have been set, or it will start bonding them together in the wrong position. Likewise, do not apply it on deep wounds, which can close at the top before the deep part has healed underneath. St John’s wort is better for deep puncture wounds.
Common comfrey’s leaves run down the stem to the joint below, giving the stem a winged appearance
Common comfrey is the commonest comfrey in wetter habitats, but the flower colour is very variable, ranging from creamy white through pink to dull purple. The leaves run down onto the stem, with the upper leaves extending right down to the next set of leaves, giving the stem a winged appearance (see photo).
Russian comfrey is the most common comfrey in drier places. Its flowers are bright blue or purple, and the upper stem leaves don’t run down the stem, or do so only slightly. Rough comfrey, its other parent plant, has bluish flowers and the upper stem leaves have short stalks and never run down the stem.
Comfrey and the pyrrolizidine alkaloid controversy
Comfrey has come into disrepute in recent years because it contains pyrrolizidine alkaloids. This is a large group of chemicals, some of which are toxic to the liver and can cause hepatic veno-occlusive disease. Poisoning has been reported in people eating other plants with high levels of these alkaloids, and there are a few reported cases of liver damage that appear to be based on the use of comfrey root.
Some herbalists argue that comfrey has been used traditionally and safely for hundreds of years without any problems, but the other side of the argument is that damage could occur gradually over time and not be attributed to the herb.
Another factor is the fact that Russian comfrey has been promoted for its benefits as a fertiliser and in making compost, especially for organic gardeners. It is wonderful for this purpose, but the problem from a medicinal point of view is that this is now the comfrey that most people have growing in their gardens.
Its levels of pyrrolizidine alkaloids are much higher than those of common comfrey, the ‘official’ species of herbalism. Russian comfrey and rough comfrey, both introduced but now naturalised in Britain and Ireland, contain echimidine, the most toxic of the alkaloids, and are best limited to external use.
Russian comfrey is a hybrid between common comfrey and rough comfrey. It appears likely that comfrey was safe to use in the past when only common comfrey grew in Britain. Today the species hybridise readily and can be difficult to tell apart, but see above for guidelines.
It is better to err on the side of caution rather than risk any problems, so it is recommended that no comfrey root be used internally (it contains higher levels of alkaloids than the leaves).
Common comfrey leaf can be taken internally for short periods, not exceeding six weeks at a time. This is long enough to heal a broken bone. Do not take internally during pregnancy, while breastfeeding or if you have liver disease.
Bisset and Wichtl (2001) say that a high level of consumption of the leaves ‘as a salad is five or six leaves a day’, which would be within the toxic range. Using a couple of leaves a day to make tea should be all right for short-term use, and external use on unbroken skin is considered safe.
Fresh comfrey poultice
Dig up comfrey roots and scrub them well. Cut them into shorter lengths and put them in a blender with an equal amount of fresh comfrey leaf. Add just enough water to make it blendable, and blend until you have a gooey mess. Spread this onto a piece of gauze and apply to the body part affected, covering with a piece of muslin or cling-film. The gauze makes the poultice easier to remove. Replace poultice daily until healed.
The leaves can also be used on their own as a poultice, but the hairs on them can irritate the skin. To avoid this, blend the leaves with a little water or pound them in a mortar and pestle, and then sandwich the leaf mush between two pieces of muslin before applying to the skin. The muslin will protect the skin from the irritating effects of the leaf hairs, and allow the juices to seep through.
Infused comfrey oil
Pick comfrey leaves and let them dry in the shade; then crumble them up and put into a jar big enough to hold them. Pour in extra virgin olive oil, and stir well. Top up the jar with a little more oil, put the lid on and place in a sunny part of the garden or on a windowsill for two weeks. Strain off the oil and bottle it, or use it to make an ointment (below).
Comfrey ointment
Put 300ml of infused comfrey oil (above) in a small saucepan with 25g beeswax. The beeswax will melt faster if you grate it or slice it up. Warm up on low heat until the beeswax melts. Allow to cool slightly, then pour into jars and leave to set before putting the lids on and labelling.
Russian comfrey (S. x uplandicum) growing in a country lane, Norfolk, July