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Botanical Name

Symphytum Officinale

Common Name

Comfrey, knitbone, woundwort, knitback, blackwort, bruisewort, slippery root, boneset, gum plant



Parts Used

Leaves, root

Native To

Europe and temperate Asia

Harvesting Guidelines

Comfrey is a versatile plant that can be harvested multiple times throughout the growing season. To ensure the best quality, it's recommended to harvest comfrey when it reaches a height of 12-18 inches, but before it blooms. When harvesting, shear off the stems 2 inches above the ground to encourage regrowth. Keep in mind that comfrey leaves have a high moisture and protein content, so they may take longer to dry than other plants. For those interested in harvesting the root, the best time to do so is in the early spring, from January through March, when it contains the most allantoin.(1)


Despite being viewed as a nuisance by hikers and gardeners, comfrey has a rich history of medicinal use dating back over 2000 years. The Greeks were among the first to use comfrey for its healing properties, using it to stop bleeding and alleviate respiratory issues around 400 BCE. In fact, the renowned Greek physician Dioscorides recommended comfrey for treating wounds and broken bones in the first century. Today, comfrey is still used in herbal medicine for its various therapeutic benefits.(2)

Comfrey, a perennial herb with a long history of medicinal use, was commonly grown in monastery gardens and used by monks to treat respiratory issues and internal injuries in the surrounding villages. In the 18th century, herbalist Nicholas Culpeper also recognized the healing properties of comfrey root, using it to alleviate hemorrhoids, blood in the urine, and pain. Today, comfrey is still used in natural remedies for its anti-inflammatory and pain-relieving effects.

Comfrey, a plant with a long history of medicinal use, has been traditionally used for external applications such as fomentations and poultices to treat a variety of ailments including sprains, bruises, and abscesses. The Cherokee people have also used comfrey topically to address skin conditions and injuries such as sprains and contusions. In addition to its medicinal uses, comfrey is also used in cosmetics for its anti-inflammatory, vulnerary, and antiseptic properties, making it a valuable ally in dealing with troubled skin.(3)

Comfrey, a plant with a long history of medicinal use, has been found to be effective in reducing osteoarthritis pain. In a clinical trial conducted by Grube , 220 participants suffering from knee pain due to osteoarthritis were given a comfrey extract gel. After just three weeks of treatment, those who received the comfrey gel reported significant reductions in pain and improvements in mobility and quality of life compared to those who received a placebo. This suggests that comfrey may be a promising natural remedy for those suffering from osteoarthritis.(4)

Before comfrey was linked to liver damage and its internal use was banned in many countries, it was commonly ingested in the form of teas, tinctures, capsules, and other supplements. Comfrey leaves and roots were also sometimes used in cooking as a vegetable or added to salads.

Comfrey was widely used as a traditional remedy for a variety of conditions, including digestive problems, respiratory infections, and joint pain. It was believed to have anti-inflammatory, pain-relieving, and wound-healing properties, and was used both internally and externally. The compound in comfrey that is believed to promote bone healing is allantoin, a chemical compound that is found in high concentrations in comfrey roots and leaves. Allantoin is known for its ability to promote cell proliferation and tissue regeneration, and is often used in skin care products for its soothing and healing properties.

In terms of bone healing, allantoin is thought to stimulate the production of osteoblasts, which are cells that help build new bone tissue. By promoting the growth and activity of osteoblasts, allantoin may help speed up the bone healing process and improve the strength and stability of the new bone tissue.

Although comfrey is commonly used in topical products, its internal use is not recommended due to the presence of pyrrolizidine alkaloids (PAs). These compounds have been found to be harmful to the liver in both humans and livestock, and have been shown to be carcinogenic in laboratory animals, according to a study conducted in 2005.(5)


Adult Dose (6)

While comfrey can be used externally in various forms such as poultices, compresses, soaks, infused oils, or salves, it is not recommended for internal use due to safety concerns. In Germany, there are guidelines for the safe use of external comfrey preparations, limiting exposure to 100 μg unsaturated PAs per day for a maximum of 4-6 weeks per year. It is important to follow these guidelines to ensure safe and effective use of comfrey.


Comfrey, a plant with medicinal properties, has been a topic of debate among herbalists, scientists, and governments since the 1970s. The plant contains PAs, which have been found to be toxic. However, the clinical circumstances under which these conclusions were drawn require further examination. For more information on the uses of comfrey, refer to the Uses section. Despite its potential benefits, it is important to consider the potential toxicity of comfrey before using it.




(1)Staiger, C. (2012). Comfrey: A clinical overview. Phytotherapy Research, 26(10), 1441-1448.

(2)Kowalchik, C., & Hylton, W. (Eds.). (1998). Rodale’s illustrated encyclopedia of herbs. Rodale Press.

(3)Garrett, J.T. (2003). The Cherokee herbal: Native plant medicine from the four directions. Bear & Company.

(4)Grube, B., Grünwald, J., Krug, L., & Staiger, C. (2007). Efficacy of a comfrey root (Symphyti offic. radix) extract ointment in the treatment of patients with painful osteoarthritis of the knee: Results of a double-blind, randomised, bicenter, placebo-controlled trial. Phytomedicine, 14(1), 2-10.

(5)Mei, N., Guo, L., Fu, P.P., Heflich, R.H., & Chen, T. (2005). Mutagenicity of comfrey (Symphytum officinale) in rat liver. British Journal of Cancer, 92(5), 873-875.

(6)Gardner, Z., & McGuffin, M. (Eds.). (2013). American Herbal Products Association’s botanical safety handbook (2nd ed.). CRC Press.


Scientific Research:

Information offered on Achula and on this page is for educational purposes only. Achula makes neither medical claim, nor intends to diagnose or treat medical conditions. Women who are pregnant or nursing, and persons with known medical conditions, should consult their licensed healthcare provider before taking any herbal product. Links to external sites are for informational purposes only. Achula neither endorses them nor is in any way responsible for their content. Readers must do their own research concerning the safety and usage of any herbs or supplements.


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