Comfrey (Symphytum officinale) may show up in your yard, but you're not likely to find it in the herbal supplements. We'll share why it has a questionable reputation, and tips to use it safely.
Range and Identification of Comfrey
Comfrey is native to Europe through Siberia, but grows throughout much of the U.S. and up into Canada. It prefers moist soil, and is often found as a garden escapee. Russian comfrey (S.x uplandicum) is a hybrid between common comfrey and prickly or rough comfrey, and prefers drier ground.
Symphytum officinale is a perennial, blooming in the spring/summer and dying back in fall/winter. It has a dense, clumping habit and grows up to 3 feet in height. Flowering stalks have leaves attached in an alternating pattern up the stem.
Flowers appear in clusters at the top of the stem. They are delicate and bell-shaped, with only a slight aroma. The blooms measure about 1/2 ” in length, and come in an assortment of colors including white, pink and blue.
The plant looks similar to foxglove before flowering, but foxglove flowers are larger and more showy. Make sure you have a positive ID, as foxglove is toxic.
Comfrey leaves are lance shaped, and reach up to 1 1/2 feet in length. Like borage, the leaves are hairy and rough. (Comfrey is in the borage family.) As you can see, the veining is quite pronounced.
On the leaf stem of common comfrey, there are small green wings that flair out on either side of the stem. Rough comfrey has no flare at the base of the leaf, Russian comfrey has some.
Be warned, comfrey may try to take over the garden. Common comfrey spreads more readily than Russian comfrey, and also self-seeds.
The roots have a branching habit, forming dense clusters that are difficult to remove. They are brittle and break easily, and a new plant will regrow from the leftover bits. (Don't plant them in a spot unless you're sure you want them there.) The roots are dark brown on the outside and white on the inside and measure less than 1/2 inch in diameter.
Why is Comfrey Illegal in the US?
Comfrey contains pyrrolizidine alkaloids, which are naturally occurring plant toxins. If consumed in large amounts, these can be toxic to the liver. In 2001, the Food and Drug Administration advised dietary supplement manufacturers to remove comfrey products from the market.
From their statement:
These plants contain pyrrolizidine alkaloids, substances which are firmly established to be hepatotoxins in animals. Reports in the scientific literature clearly associate oral exposure of comfrey and pyrrolizidine alkaloids with the occurrence of veno-occlusive disease (VOD) in animals.
Is Comfrey Really Toxic?
They're worried about liver damage and liver disease. The thing is, most of the studies showing adverse effects used extremely large amounts of the herb over long periods of time. Some used the isolated compounds instead of the whole herb. Different species were lumped together, and they don't all have the same amount of the compounds.
Russian comfrey has higher pyrrolizidine alkaloid levels than common comfrey. Mature leaves have a much lower concentration of the toxins than the roots. Many herbalists now recommend alternative herbal medicines for internal use, just to be safe.
Is it Safe for Animals?
Illinois Wildflowers notes that many bees enjoy the flowers, but mammals, like humans, may have problems ingesting the plant.
Horses, cattle, goats, and pigs are susceptible to being poisoned; apparently sheep are more resistant to adverse reactions.
Safe Uses of Comfrey
As its many folk names suggest, comfrey is one of the best herbs for healing broken bones, sprains, strains, bruises, and tears. One of the active compounds in comfrey is allantoin. This anti-inflammatory chemical stimulates cell proliferation and supports the immune system.
The plant also contains tannins, mucilage, gum, resin and volatile oil. The roots were commonly used for bronchitis and other chest complaints, and for stomach issues such as ulcers, but now other herbs are generally recommended. The Holistic Herbal discusses more of these other uses.
Backyard Medicine uses the roots and leaves for a topical comfrey poultice. Dig up the roots, clean and chop into short lengths. Blend with an equal amount of fresh comfrey leaf and just enough water to mix. Puree until relatively smooth.
Apply the puree to a piece of gauze and place over the affected body part. Cover with breathable wrapping, and replace daily.
Try the poultice for:
- broken bones
- sports injuries
- surgical scars
I had a chance to check out the healing properties of comfrey first hand when I sliced my fingertip open. The cut was about one inch long and 1/8 inch deep at the deepest. It bled like crazy, so I knew the wound had been flushed out.
I made a compress of fresh comfrey leaves and dried yarrow, which is antibacterial and also known for treating wounds. I kept the compress on it for 24 hours, and kept it covered for another 24.
The cut happened Monday night, and this is what the wound looks like on Wednesday morning. No scab, no scar, no pain – which is great, because I still have a lot of canning to do. (More on comfrey's wound healing effects here.)
Try Comfrey Salve to Speed Up Healing
For your herbal medicine cabinet, dry the leaves and infuse them in olive oil, then turn the oil into a salve by adding beeswax. Heat 10 fluid ounces of infused oil with 1 ounce of grated beeswax until the wax melts. Allow to cool slightly, then pour into containers. (See more information on infusing oils here.)
Try the salve for:
- glandular swellings
- pulled muscles
- injured joints
- back injuries
Comfrey may improve circulatory conditions, such as varicose veins and spider veins. Backyard Medicine also suggests that it may be helpful skin issues, like healing old wounds, such as surgical scars, and minor cuts.
Do not use comfrey for topical treatment of deep cuts or puncture wounds. It may cause the would to close at the top before it heals underneath, increasing the risk of abscess/infection.
Don't have time to make your own salve, try Dr. Christopher's Comfrey Ointment.
This article is not meant to replace medical advice from a trained practitioner. Always exercise caution when using any wild plants and make sure you have positively identified the plant. Check for drug interactions or side effects if you are on any medications.
Comfrey in the Garden
In The Homesteader's Herbal Companion, Amy recommends comfrey tea for plant fertilizer. Simply place comfrey leaves in a bucket, weight them down, and then cover with water. Let sit for around 2 weeks, and then strain.
Use to water your plants, or dilute and use as a foliar feed spray.
Other Names for Symphytum officinale
Comfrey (Symphytum officinale) is also known as knitbone, knitback, knit bond, Quaker comfrey, black root, blackwort, bruisewort, slippery root, boneset, gum plant, healing herb, wallwort and salsify. It is not related to salsify/oyster plant (Tragopogon porrifolius), a garden root vegetable.
The Weekly Weeder Series
This post is #40 in the Weekly Weeder series, which is all about helping you use wild plants.
Other posts in the series include:
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Originally posted in 2013, last updated in 2021.