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.]