Cnidium (Cnidium monnieri) has a long history of use in Traditional Chinese Medicine (TCM), where it is known as "She Chuang Zi." It has been employed for a variety of purposes, most notably for skin conditions and as an aphrodisiac, but also sometimes for menstrual and gynecological issues, including cramps and irregular menstruation. In the context of menstrual cramps, traditional use is based largely on its purported ability to "move qi" and dispel "wind and dampness," concepts in TCM associated with relieving pain and promoting circulation.

Scientifically, there is limited evidence to support the use of Cnidium specifically for menstrual cramps. Most modern research has focused on its effects as an anti-inflammatory, antimicrobial, or aphrodisiac agent rather than as a direct treatment for dysmenorrhea (menstrual cramps). Some animal studies suggest that compounds in Cnidium, such as osthole, may have smooth muscle relaxant properties, which could theoretically help with cramping, but robust clinical trials in humans addressing menstrual pain specifically are lacking.

In summary, while Cnidium's use for menstrual cramps is supported by traditional herbal practices, particularly in East Asia, there is insufficient scientific evidence to strongly validate its efficacy for this particular condition.