Comfrey grows natively in Europe and western Asia, and the roots and leaves are used in medicinal preparations. You might use topical remedies containing comfrey root extract to treat sprains, bruises, wounds, broken bones and more. Comfrey root contains some toxic substances that pose serious health risks, however, so you should talk with your doctor before using any remedy containing this herb.
Historically, herbalists used oral and topical remedies containing comfrey root to promote the healing of bones, earning the herb the Latin name Symphytum, meaning “drawing together,” and the common names knitbone and boneset. Herbalists also used creams made from comfrey root to apply topically to wounds, sprains or strains, bruises and varicose veins, says the University of Pittsburgh Medical Center. People also took the root orally to treat lung problems, stomach ulcers and other gastrointestinal problems, and an eyewash made from comfrey was used to treat eye problems and irritations, notes the University of Michigan Health System.
Today, you may use topical or oral remedies containing comfrey root extract for many of the same traditional purposes. You might use topical comfrey root remedies to treat back pain, sprains and strains, bone fractures, bruises, varicose veins, conjunctivitis, skin ulcers and minor wounds. Although these are the proposed uses for comfrey root extract, you should talk with your health care provider before using comfrey herbal remedies.
To apply comfrey to affected skin areas, simmer 3 ½ ounces of fresh or dried peeled root in 1 pint of water for 10 or 15 minutes and soak a cloth in the liquid, says the University of Michigan Health System. Then, you can apply the cloth to the skin area for about 15 minutes several times each day. You can also use ointments or creams containing 25-percent comfrey root extract. Discuss this application method with your doctor first.
Comfrey root contains the active constituents called allantoin, rosmaric acid and mucilage, which provide the herb’s anti-inflammatory and pain-relieving effects. Rosmaric acid in particular may help to prevent pulmonary vascular injuries as well, says the Memorial Sloan-Kettering Cancer Center. Unfortunately, comfrey root also contains large amounts of pyrrolizidine alkaloids, which are toxic and can cause serious liver damage or even death. This is why comfrey root extract isn’t recommended for internal remedies.
A 2004 double-blind study of 142 people suffering from ankle sprains found that applying comfrey root extract cream helped to reduce healing time, pain and swelling over the course of eight days, compared to placebo, says the University of Pittsburgh Medical Center. Another double-blind clinical trial published in 2009 found that comfrey root extract ointment helped to treat acute back pain, according to the Memorial Sloan-Kettering Cancer Center. A three-week-long, double-blind study of 220 people published in 2006 also found that comfrey root extract ointment relieved symptoms related to osteoarthritis of the knee, compared to placebo. A 2007 study of mice indicated that comfrey root extract had antiproliferative actions in hepatic cancer cells. Finally, a 2007 double-blind study of 278 people with fresh skin abrasions determined that applying a 10-percent concentration comfrey cream increased wound healing speed after just two to three days. None of these studies and clinical trials prove that comfrey root is safe and effective for treating any medical condition, so be sure to consult your physician before using comfrey remedies.
The pyrrolizidine alkaloids contained in comfrey root can seriously harm your liver and may be carcinogenic. Several cases published in 1999 reported that people developed dangerous liver problems or liver disease after taking comfrey root extract capsules or teas, says the University of Michigan Health System. Even short-term internal use of comfrey root extract can cause liver failure, even leading to the need for a liver transplant. In fact, the U.S. Food and Drug Administration ordered that all supplements containing comfrey root be pulled from store shelves due to the liver toxicity risks. Although you’re most at risk for liver damage when you take comfrey root remedies orally, topical applications may also be dangerous because you can absorb pyrrolizidine alkaloids through your skin. Therefore, you shouldn’t use comfrey extracts before first talking with a health care professional, or use extracts containing more than 100 mcg of pyrrolizidine alkaloids in each daily dose. Also, don’t use comfrey root extract creams or ointments for longer than 10 consecutive days or more than six weeks in a single year.