Treatment of low back pain exacerbations with willow bark extract: A randomized double-blind study

PURPOSE: Herbal medicines are widely used for the treatment of pain, althou gh there is not much information on their effectiveness. This study was des igned to evaluate the effectiveness of willow (Salix) bark extract, which i s widely used in Europe, for the treatment of low back pain. SUBJECTS AND METHODS: We enrolled 210 patients with an exacerbation of chro nic low back pain who reported current pain of 5 or more (out of 10) on a v isual analog scale. They were randomly assigned to receive an oral willow b ark extract with either 120 mg (low dose) or 240 mg (high dose) of salicin, or placebo, with tramadol as the sole rescue medication, in a 4-week blind ed trial. The principal outcome measure was the proportion of patients who were pain-free without tramadol for at least 5 days during the final week o f the study. RESULTS: The treatment and placebo groups were similar at baseline in 114 o f 120 clinical features. A total of 191 patients completed the study. The n umbers of pain-free patients in the last week of treatment were 27 (39%) of 65 in the group receiving high-dose extract, 25 (21%) of 67 in the group r eceiving low-dose extract, and 4 (6%) of 59 in the placebo group (P < 0.001 ). The response in the high-dose group was evident after only 1 week of tre atment. Significantly more patients in the placebo group required tramadol (P < 0.001) during each week of the study. One patient suffered a severe al lergic reaction, perhaps to the extract. CONCLUSION: Willow bark extract may be a useful and safe treatment for low back pain. Am J Med, 2000;109:9-14. (C) 2000 by Excerpta Medica, Inc.