Is Four Agents Decoction (Si Wu Tang) An Effective Treatment For Menstrual Pain?

Science Daily — New research by scientists in Taiwan has shown that an 800-year-old formula, Four-Agents Decoction (Si Wu Tang), does not significantly reduce menstrual pain after three cycles of treatment; however, a beneficial effect may be present after a longer treatment. The dosage regimen and treatment length used in this study are not associated with adverse reactions.

Four-Agents Decoction is composed of dry roots of four plants native to China: prepared Radix Rehmanniae praeparata (Soe Dee Huang), Radix Paeoniae Alba (Bai Sau), Radix Angelicae Sinensis (Dang Guay), and Rhizoma Ligustici Chuanxiong (Tsuan Chyong). This formula is originally listed in the Prescriptions of People's Welfare Pharmacy (in Chinese) as a remedy for nourishing the blood and has been used as a basic formula in traditional Chinese medicine for treating women's illnesses since the Song dynasty (twelfth century). Although many analgesics are available, this formula is worth studying, as non-specified dysmenorrhoea is still one of the most common gynecological complaints in young women worldwide.

The participants in the study were 78 primary dysmenorrheic women in the Taipei, Taiwan, metropolitan area. At the end of treatment, both menstrual overall--pain- and peak-pain-intensity did not differ significantly between the Four-Agents-Decoction group and the placebo group. But statistically significant pain-reducing effect appeared in the first follow-up cycle.

"We did not obtain clear evidence for our hypothesis that Four-Agents-Decoction had a beneficial effect to treat primary dysmenorrhoea" says Dr. Lan Lan Liang Yeh, the study's principal investigator. "But the unexpected result of a statistically significant pain-reducing effect in the first post-treatment cycle is intriguing and warrants a rigorous similar trial with a larger sample size, a longer treatment phase, and multiple batched study products in different populations to determine the definitive efficacy of this historically documented formula."

The protocol underwent reviews by the National Health Research Institutes and the study received funding support from NHRI; the Department of Health, Taiwan; and the National Science and Technology Program for Biotechnology and Pharmaceuticals.

The results are published in the August 15 issue of  PLoS One.

Citation: Yeh LLL, Liu J, Lin K, Liu Y, Chiou J, et al. (2007) A Randomised Placebo-Controlled Trial of a Traditional Chinese Herbal Formula in the Treatment of Primary Dysmenorrhoea. PLoS ONE 2(8): e719. doi:10.1371/journal.pone.0000719

Note: This story has been adapted from a news release issued by Public Library of Science.