Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study.
OBJECTIVE
Herbal medicines are widely used for the treatment of pain, although there is not much information on their effectiveness. This study was designed to evaluate the effectiveness of willow (Salix) bark extract, which is widely used in Europe, for the treatment of low back pain.


METHODS
We enrolled 210 patients with an exacerbation of chronic low back pain who reported current pain of 5 or more (out of 10) on a visual analog scale. They were randomly assigned to receive an oral willow bark 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 blinded 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 of the study.


RESULTS
The treatment and placebo groups were similar at baseline in 114 of 120 clinical features. A total of 191 patients completed the study. The numbers of pain-free patients in the last week of treatment were 27 (39%) of 65 in the group receiving high-dose extract, 15 (21%) of 67 in the group receiving 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 treatment. Significantly more patients in the placebo group required tramadol (P <0.001) during each week of the study. One patient suffered a severe allergic reaction, perhaps to the extract.


CONCLUSIONS
Willow bark extract may be a useful and safe treatment for low back pain.
Pain Relief Unit, Rambam Medical Center, B. Rappaport Faculty of Medicine, Technion, Institute of Technology, Haifa, Israel.
S
S
Chrubasik
E
E
Eisenberg
E
E
Balan
T
T
Weinberger
R
R
Luzzati
C
C
Conradt
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000701:Analgesics, Opioid / Q000627:therapeutic use; D001592:Benzyl Alcohols / Q000627:therapeutic use*; D002908:Chronic Disease; D004311:Double-Blind Method; D005260:Female; D005960:Glucosides; D006801:Humans; D017116:Low Back Pain / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D010936:Plant Extracts / Q000627:therapeutic use*; D011446:Prospective Studies; D014147:Tramadol / Q000627:therapeutic use
D000701:Analgesics, Opioid; D001592:Benzyl Alcohols; D005960:Glucosides; D010936:Plant Extracts; D014147:Tramadol; C005696:salicin