Third, different modified xiaoyao prescriptions and different form of the prescriptions were used in the trials: eight trials [7, 8, 11, 16, 20, 27, 28, 31] used fixed xiaoyaowan throughout the treatment, five trials used modified xiaoyaowan, and one trial used modified xiaoyansan based on menstruation period of young female [9] . The rest thirteen trials [10, 13, 14, 18, 19, 21-24, 29, 32] used modified xiaoyao decoction according to syndrome differentiation based on Chinese medicine theory, the herbal compound varied from 7 to 17 herbs ( Table 2 ). The treatment duration varied from 30 days to 3 months.