Chinese herbs were highly effective in treating menstrual cramps in a recent study of 3,475 women in several countries.

In fact, Chinese herbs may be more effective in relieving menstrual cramps than conventional medications such as the contraceptive pill and nonsteroidal anti-inflammatory drugs, as well as acupuncture and heat compression, according to the Australia-based researchers. The Cochrane Database of Systematic Reviews 2007, Issue 4, which reported the studies, noted that while "no significant adverse effects were identified in this review … the findings should be interpreted with caution due to the generally low methodological quality of the included studies."

And experts in the United States caution retailers and consumers about the use of Chinese herbs.

"Chinese herbs, much more than Western herbs or nutraceuticals, are very specific to the pattern associated with that person," said Sarah Adlerstein, a naturopathic doctor and licensed acupuncturist in Boulder, Colo. "There's no particular formula that's for menstrual pain."

"Chinese medicine looks at all the systems of the body and looks for deficiencies and excesses," said Mark Kelley, a naturopathic doctor and licensed acupuncturist in Fort Collins, Colo.

He suggests retailers direct customers interested in Chinese medicine to a Chinese herbalist or acupuncturist rather than a product on the shelf.

"The other piece of the puzzle is that Chinese herbal formulas are known for heavy metal contaminants—lead, mercury, cadmium, arsenic," Kelley added. "That's the first thing you learn in herbal class: You have to be careful about your source. Look for manufacturers that do independent assays for toxicity."

What's more, he said, research conducted on people in one country or region is hard to apply to people in other geographies because the influential factors of diet, environment and genetics vary greatly.

The herbal research led by Xiaoshu Zhu at the Centre for Complementary Medicine Research at the University of Western Sydney involved 39 trials, 36 in China, and one each in Taiwan, Japan and the Netherlands.

Participants given herbal concoctions were prescribed herbs that regulated their qi (energy) and blood, warmed their bodies and boosted their kidney and liver functions.

Some of these included Chinese angelica root (danggui), Szechuan lovage root (chuanxiong), red peony root (chishao), white peony root (baishao), Chinese motherwort (yimucao), fennel fruit (huixiang), nut-grass rhizome (xiangfu), liquorice root (gancao) and cinnamon bark (rougui). In one trial involving 36 women, 53 percent of those who took herbs reported less pain than usual compared with 26 percent in the placebo group. The research also suggested that herbs reduced the recurrence of menstrual pain over three months.

Period pain affects as much as 50 percent of women of reproductive age and between 60 percent and 85 percent of teenaged girls, leading to absences from school and work.

While the cause is still under debate, it is believed to be linked to an imbalance in ovarian hormones. Chinese herbal medicine has been used to treat the condition for hundreds of years, and women are increasingly looking for nondrug treatments.