Comfrey is an herbal medicine used traditionally for centuries for injuries, wound healing and joint pain. Here we’ll explain how this herb works and how to use it.
 |
| Comfrey (Symphytum officinale) |
What is Comfrey?
Comfrey (Symphytum officinale) is a perennial herb in the Boraginaceae family. It is native to Europe and parts of Asia. The plant is known for its hairy, lance-shaped leaves.
It will also display clusters of bell-shaped flowers that can range in color from white to purple. Comfrey grows in damp, grassy areas such as riverbanks, ditches, and meadows.
Comfrey Compounds
Comfrey contains several bioactive compounds, including:
Allantoin: A compound with moisturizing and skin-healing properties.
Rosmarinic Acid: An antioxidant compound with anti-inflammatory effects.
Tannins: Which contribute to its astringent properties.
Alkaloids: These are generally antibiotic and antiviral. But pyrrolizidine alkaloids such as symphytine and echimidine may have toxic effects in large quantities or when consumed over a long period of time.
Comfrey Health Benefits
Wound Healing
Comfrey has a long history of use in promoting wound healing, including cuts, burns, and bruises, due to its high allantoin content.
Anti-inflammatory Effects
Rosmarinic acid and other compounds in comfrey have anti-inflammatory properties, making it beneficial for reducing inflammation and pain associated with conditions like arthritis and sprains.
Bone and Joint Health
Comfrey is used topically to relieve pain and inflammation associated with bone fractures, osteoarthritis, and rheumatoid arthritis.
Skin Health
Comfrey is applied to the skin to soothe irritations, eczema, and psoriasis, and to promote skin regeneration.
Gardening Aid
Comfrey leaves can be used as a natural fertilizer and compost accelerator due to their high nutrient content.
Traditional Medicine Uses of Comfrey
European Herbal Medicine
Comfrey has been used traditionally in Europe for centuries to treat various ailments, including wounds, bruises, and joint pain.
Traditional Chinese Medicine (TCM)
Comfrey, known as "Xuanma," is used in TCM to promote wound healing, reduce inflammation, and alleviate pain.
Human Research on Comfrey
In a 2007 study, doctors tested 278 patients with skin wounds with a 10% comfrey cream. Those who used the comfrey cream showed 49% reduction in wound size compared to 29% in the control group after 2-3 days.
In 2005, 215 patients with back pain and motion pain were tested with a 1% comfrey cream. Those using the comfrey cream had significantly less pain and more motion compared to the control group.
Another 2004 study, this from the medical school of Prague’s Charles University, tested 203 patients with ankle injury (distortion). The researchers tested a 10% comfrey cream (equivalent to 25% fresh herb) against a 1% product (equivalent to 2.5% fresh herb) by splitting the patients into two groups.
The research found the cream to be 86% effective in the higher dose and 65% effective in the lower dose in reducing pain and increasing motion.
A 2010 study tested 120 patients with back pain, with a topical application of 4 grams of ointment applied three times a day for five days. In this double blind study, the researchers from pain intensity decreased in 95% of the patients who applied the ointment versus 38% of those given the placebo.
A 2007 study from Germany tested 220 patients with osteoarthritis of the knee. They were given either 2 grams of ointment three times a day or a placebo, for three weeks. Using the VAS pain scale and the WOMAC scores, the researchers found that 55% of the patients given the ointment had significant decrease of pain versus 11% of the placebo group.
The comfrey group also reported significant increases in mobility and quality of life scores.
Another double-blind study, this on 142 patients with ankle injury found similar results. After 8 days of comfrey cream application, tenderness and pain were significantly decreased among the comfrey group.
This study also showed greater mobility of plantar flexion among the comfrey group.
Studies have also tested comfrey cream against diclofenac cream. A 2005 study tested 164 patients with ankle sprains. After seven days of treatment, the diclofenac group showed 85% pain (VAS) reduction while the comfrey group showed 92% pain reduction. Ankle swelling decreased by 80% in the comfrey group and 70% in the diclofenac group. Pain and pressure were reduced by 81% in the comfrey group compared to 75% in the diclofenac group.
Other studies that compared diclofenac to comfrey had similar findings.
Comfrey paste has also been studied. A 2004 study tested 162 patients with painful joint and muscle issues with a 30% comfrey paste. After an average 12 days of treatment, patients had a 90% morning stiffness decrease, and otherwise excellent results in 65% and “good” results in 33% of the patients.
Studies involving children also showed that comfrey significantly reduces pain, inflammation and motion restriction.
For example, a 2008 study tested 306 children between 3 and 12 years old with a variety of injuries (contusions, strains, distortions and other injuries). Most of the children were given a 35% comfrey extract cream applied three times a day, with some receiving four times and some receiving two times a day application to their injury sites.
The research found 62% had significant pain reduction, increased motion, and reduced pain sensitivity.
In all of these studies and more, there were few adverse reactions, often the placebo groups had more. Also in the children’s studies, safety protocols were met with positive results. The comfrey cream studies showed safety among the patients.
Pyrrolizidine alkaloids in Comfrey
As mentioned above, the Comfrey plant can contain pyrrolizidine alkaloids that may be toxic to the liver when consumed in large amounts or over a long period of time. These alkaloids in comfrey include acetylintermedine, echimidine, acetyllycopsamine, intermedine, lasiocarpine, myoscorpine, lycopsamine, symlandine, symviridine, and symphytine.
Over the centuries, Comfrey tea has often been consumed regularly, without observed liver effects.
However, beginning in the 1970s, some rodent studies concluded that comfrey consumption could harm the liver. The doses given in these studies could be considered out of the ordinary when converted to human consumption.
The researchers tested their liver enzymes including AST (aspartate aminotransferase), (GGT) gamma-glutamyltransferase, AFP (alpha-fetoptotein) along with bilirubin levels. These are markers for liver inflammation, cancer and other liver issues.
All of the long-term comfrey consumers tested in the normal range for these liver enzymes and markers.
That said, a few single case reports have found that internal use of comfrey could be linked to veno-occlusive disease (VOD). This is when liver blood vessels become damaged. An analysis of these case studies by Dr. Dorena Rode found the comfrey consumption link weak at best, however. Most cases also had concurrent consumption of other drugs that have been shown to harm the liver as well, including NSAIDs.
Nonetheless, this sort of risk should not apply to the topical application of comfrey. This is because the skin doesn’t efficiently absorb pyrrolizidine alkaloids (PAs). Also, the majority of PAs in plants are in the N-oxide chemical form. These do not readily convert to the toxic forms of PA, and N-oxide PAs are excreted quickly with little or no toxicity.
One study that tested comfrey extract applied topically found very tiny amounts in the urine with little conversion to the free alkaloid forms. This was one-twentieth to one-fiftieth times levels of oral consumption.
What this means is that external use – on the skin – is generally considered safe. This has been proven out in the many human studies as illustrated above.
In addition, pyrrolizidine alkaloid-free and low-PA versions of comfrey are commercially available today.
It should also be mentioned that PAs are readily available in most of our foods, include grains, dairy products and meat products. There are weeds that contain PAs, and these can easily enter the food supply. Studies have shown that most animal and human blood and urine contain PAs. Some other herbs contain PAs, but many are also available in PA-free forms.
Conclusion
The research shows that topical comfrey is safe and effective for the treatment of various types of muscle and joint injuries, as well as arthritis pain and inflammation. Reduction in pain and improved motion and flexibility has been found among these human studies.
Internal use of comfrey more caution. Lower doses and shorter duration use has been recommended. Extracts that are pyrrolizidine alkaloid-free (“PA-free) have become available recently and should provide an increased measure of safety. Even then, consult with your health professional before consuming comfrey or other herbs internally, especially for a longer period or in larger doses.
Scientific References
Brauchli J, Lüthy J, Zweifel U, Schlatter C. Pyrrolizidine alkaloids from Symphytum officinale L. and their percutaneous absorption in rats. Experientia. 1982 Sep 15;38(9):1085-7. doi: 10.1007/BF01955382.
Anderson, P. and A.E.M. McLean, Comfrey and Liver Damage. Human Toxicology, 1989. 8(1): p. 68-69.
Rode D. Comfrey toxicity revisited. Trends in Pharmacological Sciences, Volume 23, Issue 11, 2002, Pages 497-499.
Staiger C. Comfrey: a clinical overview. Phytother Res. 2012 Oct;26(10):1441-8. doi: 10.1002/ptr.4612.
Ridker PM, McDermott WV. Comfrey herb tea and hepatic veno-occlusive disease. Lancet. 1989 Mar 25;1(8639):657-8. doi: 10.1016/s0140-6736(89)92154-5.
Arungundrum S Prakash, Tamara N Pereira, Paul E.B Reilly, Alan A Seawright, Pyrrolizidine alkaloids in human diet. Mutation Research/Genetic Toxicology and Environmental Mutagenesis. Volume 443, Issues 1–2, 1999, Pages 53-67. doi: 10.1016/S1383-5742(99)00010-1.
Stickel F, Seitz HK. The efficacy and safety of comfrey. Public Health Nutr. 2000 Dec;3(4A):501-8. doi: 10.1017/s1368980000000586.
Giannetti BM, Staiger C, Bulitta M, Predel HG. Efficacy and safety of comfrey root extract ointment in the treatment of acute upper or lower back pain: results of a double-blind, randomised, placebo controlled, multicentre trial. Br J Sports Med. 2010 Jul;44(9):637-41. doi: 10.1136/bjsm.2009.058677.
Grube B, Grünwald J, Krug L, Staiger C. 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. 2007 Jan;14(1):2-10. doi: 10.1016/j.phymed.2006.11.006.
Koll R, Buhr M, Dieter R, Pabst H, Predel HG, Petrowicz O, Giannetti B, Klingenburg S, Staiger C. Efficacy and tolerance of a comfrey root extract (Extr. Rad. Symphyti) in the treatment of ankle distorsions: results of a multicenter, randomized, placebo-controlled, double-blind study. Phytomedicine. 2004 Sep;11(6):470-7. doi: 10.1016/j.phymed.2004.02.001.
Kruse LH, Stegemann T, Jensen-Kroll J, Engelhardt A, Wesseling AM, Lippert A, Ludwig-Müller J, Ober D. Reduction of Pyrrolizidine Alkaloid Levels in Comfrey (Symphytum officinale) Hairy Roots by RNAi Silencing of Homospermidine Synthase. Planta Med. 2019 Oct;85(14-15):1177-1186. doi: 10.1055/a-0998-5125.
Pabst H, Ottersbach P. Topikum bei Muskel- und Gelenkbeschwerden. Geriatr J. 2004;6(6):45–47.
Predel HG, Giannetti B, Koll R, Bulitta M, Staiger C. Efficacy of a comfrey root extract ointment in comparison to a diclofenac gel in treatment of ankle distortions: results of an observer-blind, randomized, multicenter study. Phytomedicine. 2005;12:707–714. doi: 10.1016/j.phymed.2005.06.001.
Koll R, Buhr M, Dieter R, et al. Efficacy and tolerance of a comfrey root extract (Extr. Rad. Symphyti) in the treatment of ankle distortions: results of a multicenter, randomized, placebo-controlled, double-blind study. Phytomedicine. 2004;11:470–477. doi: 10.1016/j.phymed.2004.02.001.
Smith DB, Jacobson BH. Effect of a blend of comfrey root extract (Symphytum officinale L.) and tannic acid creams in the treatment of osteoarthritis of the knee: randomized, placebo-controlled, double-blind, multiclinical trials. J Chiropr Med. 2011 Sep;10(3):147-56. doi: 10.1016/j.jcm.2011.01.003.