Herbal Medicines to Treat Low Back Pain
Gagnier JJ, van Tulder M, Berman B, Bombardier C. Herbal medicine for low back pain (review). Cochrane Database Syst Rev.. April 19, 2006;(2):CD004504.
Back pain is a common condition. In the United States, it is the most common cause of disability in people younger than 45 years.1 Low back pain is the second most frequent cause of work absence in industrialized nations2 and is a frequent reason for visits to a physician.3,4 These authors conducted a review of the scientific literature to determine the effectiveness of herbal medicines compared with placebo, no intervention, or other interventions in the treatment of nonspecific low back pain (defined as "pain between the lowest rib and the bottom of the buttocks that is not caused by serious, underlying problems such as rheumatoid arthritis, infection, fracture, cancer, or sciatica due to a herniated disc or other pressure on nerves").
Included in this review were randomized controlled trials (RCTs) including adults (older than 18 years) suffering from acute (lasting up to 6 weeks), subacute (lasting 6 to 12 weeks), or chronic (lasting longer than 12 weeks) nonspecific low back pain. Herbal medicine was defined as "all or part of a plant that was used for medicinal purposes, administered orally or applied topically." Outcome measures were pain intensity, functional status, overall improvement, and work status.
The authors searched these databases: Cochrane Complementary Medicine Field Trials Registry (Issue 3, 2005); MEDLINE (1966 to July 2005); EMBASE (1980 to July 2005); and Clinical Evidence (January 2005). In addition, they reviewed reference lists in review articles, guidelines, and in the retrieved articles, and contacted persons with expertise in herbal medicine and low back pain to identify additional trials. Methodological quality and clinical relevance were assessed separately by two of the authors; disagreements were resolved by consensus.
For this review, 10 citations met the inclusion criteria. Three studies used an oral form of the herbal species devil's claw (Harpagophytum procumbens); 3 used oral white willow bark (Salix alba); and 4 used topical cayenne (Capsicum frutescens). Four studies compared various oral herbal medicines with placebo; 2 studies compared oral herbal medicines with standard pain medications; 3 studies compared topical herbal medicines with placebo, and 1 compared a topical herbal medicine with a topical homeopathic medicine.
The authors note that most of the trials reviewed are of moderate or high quality but they only tested the effects of short-term (up to 6 weeks) use. Also, the authors of half of the studies were judged to have a potential conflict of interest, and two others did not discuss conflict of interest.
After conducting the review, the authors conclude that an aqueous devil's claw extract at a standardized daily dosage of 50 mg harpagoside, a white willow bark extract at a standardized dosage of 240 mg salicin per day, and cayenne plaster seem to reduce low back pain more than placebo. "These herbal medicines could be considered as treatment options for acute episodes of chronic low back pain," they write.
Following are the studies reviewed by these authors.
Oral Herbal Medicines Versus Placebo
One 4-week trial tested an extract of devil's claw standardized to 50 mg harpagoside (H) per day versus placebo in 118 patients with chronic low back pain. Results showed a significant increase in the number of pain-free patients in the 50 mg H group (9% to 17%) over the placebo group (2% to 5%). In another 4-week trial, 197 patients were given either a daily dose of 100 mg H, 50 mg H, or placebo. The number of patients who were pain free for at least 5 days in the fourth week of treatment was significantly higher in the 100 mg group than in either the placebo group or the lower dose (50 mg H