Menstrual cramps are usually the result of inflammation in the uterine lining and contractions triggered by prostaglandins (fatty acid compounds with hormone-like effects). Willow bark has the ability to regulate the production of prostaglandins and reduce inflammation, which can help soothe cramps and PMS symptoms. According to the University of Maryland Medical Center, professionals of herbal medicine recommend taking willow bark for menstrual cramps, but scientific research has yet to be completed to prove these benefits.