Comfrey herb, tea and root benefit, side effects, risks - Symphytum officinale Ray Sahelian, M.D.
April 17 2015

Comfrey is a perennial herb with a black, turnip-like root and large, hairy broad leaves. This medicinal herb has long been used to treat painful joint and muscular conditions.

Wien Med Wochenschr. 2013. Comfrey root: from tradition to modern clinical trials. Comfrey (Symphytum officinale L.) has been used over many centuries as a medicinal plant. In particular, the use of the root has a longstanding tradition. Today, several randomised controlled trials have demonstrated the efficacy and safety. Comfrey root extract has been used for the topical treatment of painful muscle and joint complaints. It is clinically proven to relieve pain, inflammation and swelling of muscles and joints in the case of degenerative arthritis, acute myalgia in the back, sprains, contusions and strains after sports injuries and accidents, also in children aged 3 years and older. This paper provides information on clinical trials, non-interventional studies and further literature published on comfrey root till date.

Caution, safety
The use of comfrey herb in dietary supplements is a concern since this plant contain pyrrolizidine alkaloids. Pyrrolizidine alkaloids and their N-oxides are found in several plant families throughout the world. Pyrrolizidine alkaloids are potentially toxic to the liver and/or lungs in humans and may cause acute liver failure, cirrhosis, pneumonitis, or pulmonary hypertension. Pyrrolizidine alkaloids are also carcinogenic to animals, and they have been linked to the development of liver cancer and skin squamous cell carcinomas.

Complement Ther Med. 2013. A critical scoping review of external uses of comfrey (Symphytum spp.). External preparations of the herb comfrey (most commonly Symphytum officinale L.) are widely available for over-the-counter, practitioner and healthcare professional usage. Traditional practice suggests comfrey can be used to treat musculoskeletal disorders, wounds and various other conditions; however a full and critical coverage of the evidence base has not yet been undertaken Individual clinical trials showed evidence of benefit for ankle distortion, back pain, abrasion wounds and osteoarthritis. Topical application appears to be safe but further rigorous assessment is needed.

Comfrey for skin
Comfrey herb extract has wound healing effects when applied topically

Comfrey ointment for arthritis
Comfrey root extract ointment is helpful as a treatment of osteoarthritis of the knee.

Back pain treatment
Topical treatment with comfrey root extract ointment can reduce acute upper and lower back pain. Dr. Christiane Staiger, from Merck Selbstmedikation GmbH, Darmstadt, Germany, assessed back pain in 120 patients who were randomly assigned to receive 4 grams of comfrey root extract ointment or a placebo ointment three times daily for 5 days. Between the first and fourth (and final) follow-up assessment, pain intensity dropped by 95 percent in the comfrey root extract group, while pain was reduced by 39 percent in the placebo group. Pain relief after application of the extract was rapid, usually beginning in less than one hour. As pain improved, patients' mobility did also. Dr. Christiane Staiger says, "Comfrey root extract shows a remarkably potent and clinically relevant effect in reducing acute back pain." British Journal of Sports Medicine, 2009.

About the plant
Symphytum officinale is commonly found in Europe and Asia and is a member of the Borage and Forget-me-not family, Boraginaceae. Comfrey may grow about 3 feet high, blooms from early spring throughout the summer, and is distinguished by its yellow and sometimes purple bell-shaped flowers.

I have read that chewing comfrey leaves will help a lot with asthma. Is this true, I have also read that it can damage other organs such as liver and kidneys.
   Yes, this herb has toxins which may damage the liver.

I have used comfrey cream (mfd. by Merck) topically for rheumatic pain and found that it gives good results. I notice from the packet that this product should only be used for 10 days at a time and for 4-6 weeks per year max. I believe that the reasoning behind this is that the product contains pyrrolizidine alkaloids, which have been implicated in liver toxicity. I would like to be able to use the product daily, on a continuing basis. Do you consider it likely that problems would occur, were the product to be used on a continuous basis?
   Unfortunately not enough studies are available to determine the long term benefits and risks of comfrey cream use.