Herb World News Online

Herb Research Foundation


 Top News  |  World  |  Science  |  Research Reviews  |  Politics  |  Industry  |  Features
 Research Reviews

Willow Bark Extract Reduces Low Back Pain

In spite of its long and compelling history of traditional use, there is little research-based information on willow bark (Salix alba L., Salicaceae) as a pain reliever, and dosages recommended by official sources are often contradictory. To clarify dosage issues, a team of German researchers conducted a four-week clinical trial designed to compare the effectiveness and safety of two different dosages of willow bark extract for alleviating flare-ups of low back pain (Chrubasik et al., 2000). Results showed that both the high and low doses of willow bark extract afforded significantly more pain relief than placebo, but the higher dose of willow bark (240 mg/day) was significantly more effective than either the low-dose treatment or the placebo.

The placebo-controlled study involved 210 chronic low-back pain sufferers currently experiencing exacerbations of pain (rated 5 or higher out of a possible score of 10 on a visual pain-approximation scale). The study participants were randomly assigned to receive willow bark extract at a low dose (120 mg/day) or a high dose (240 mg/day), or a placebo. Patients were permitted to supplement their test treatment as needed with up to 400 mg per day of tramadol, a prescription pain reliever.

Ninety-one percent of patients completed the trial. The main outcome measured was pain relief, defined as the proportion of patients reporting freedom from pain for at least 5 days during the last week of treatment, without the use of tramadol. Secondary measurements were the proportion of patients who needed to use tramadol during the study and improvement in symptoms from baseline. According to the results, 39 percent of participants in the high-dose willow group were pain-free during the final week of treatment, as compared to 21 percent of the low-dose group and only six percent of the placebo group. For those taking the higher dose of willow bark, pain relief was evident after only one week, and significantly more people in the placebo group required tramadol during each week of the study. There was a similar low rate of mild adverse effects among all three groups, some of which were attributed to tramadol. One patient in the low-dose willow group experienced an allergic reaction (swollen eyes and itching) that the investigators believed was treatment-related.

The willow bark preparation used in the study was a dry extract containing 0.153 mg of salicin per mg of extract, manufactured by Plantina GmbH of Munich, Germany. According to the researchers, results of this trial support earlier reports that willow bark extract "standardized to yield 240 mg of salicin" is an effective pain reliever (Schaffner et al., 1997; Schmid et al., 1998).

- Evelyn Leigh, Herb Research Foundation [Chrubasik S, Eisenberg E, Balan E, Weinberger T, Luzzati R, Conradt C. Treatment of low back pain exacerbations with willow bark extract: A randomized double-blind study. Am J Med 2000; 109: 9-14. Schaffner E. Eidenrinde-Ein Antiarrheumatikum der modernen Phytotherapie? In: Chrubasik S, Wink M, eds. Rheumatherapie mit Phytopharmaka. Stuttgart: Hippokrates-Verlag; 1997: 125-127. Schmid B, Tschirdewahn B, Katter I, et al. Analgesic effects of willow bark extract in osteroarthritis: results of a clinical double-blind trial. Fact 1998; 3: 186.]

 Top News  |  World  |  Science  |  Research Reviews  |  Politics  |  Industry  |  Features

Back to the Herb World News Online Front Page

© 2003 by Herb Research Foundation, Boulder, CO, USA.

Main Page