Significance of this Cochrane Review. Back Pain is common, affecting as much as 35% of the population in a given month. Non-specific low-back pain is 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. Oral and topical herbal medicines are being used to treat many conditions; several are used for back pain and have been tested in clinical trials.
Description of the trials. Three oral herbal medications were tested in ten randomised controlled trials that included 1567 adults with non-specific acute or chronic low-back pain. Two oral herbal medications, Harpagophytum Procumbens (Devil’s Claw) and Salix Alba (White Willow Bark), were compared with placebo (fake pills) and with rofecoxib (Vioxx). Topical Capsicum frutescens (Cayenne) was compared with placebo and a homeopathic gel.
Findings. Devil’s Claw, in a standardised daily dose of 50 mg or 100 mg harpagoside, seemed to reduce pain more than placebo; a standardised daily dose of 60 mg reduced pain about the same as a daily dose of 12.5 mg of Vioxx. While Willow Bark, in a standardised daily dose of 120 mg and 240 mg of salicin reduced pain more than placebo; a standardised daily dose of 240 mg reduced pain about the same as a daily dose of 12.5 mg of Vioxx. Cayenne was tested in plaster form and reduced pain more than placebo and about the same as the homeopathic gel Spiroflor SLR. Adverse effects were reported, but appeared to be primarily confined to mild, transient gastrointestinal complaints.
Limitations. Most of the trials were of moderate or high quality, but they only tested the effects of short term use (up to six weeks). 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. Vioxx has been withdrawn from the market because of adverse effects, so all three substances should be compared with readily available pain medications such as non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen, to test for relative effectiveness and safety.
Conclusion. Although there are good results with three herbal medicines in short-term trials, with strong evidence for a particular form of one of the herbal medicines, there is no evidence yet that any of these substances are safe and useful for long term use.