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Is 4 agents decoction efficacious in treating primary dysmenorrhea?

A finding from a randomized double-blind clinical trial


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. The results are published in the August 15 issue of the online, open-access journal PLoS ONE.

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 following press release refers to an article in PLoS ONE. The release has been provided by the article authors and/or their institutions. Any opinions expressed in this are the personal views of the contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the release and article and your use of such information.

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.

Notes for editors The government of Taiwan established the National Health Research Institutes in 1996. NHRI is a non-profit, autonomous research organization dedicated to the enhancement of medical research and the improvement of health care in Taiwan.

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


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