3.1. Description of included trialsThe searches identified 746 potentially relevant studies, ofwhich three met our inclusion criteria (Fig. 1). The key data fromall included RCTs are summarized in Table 1. Three RCTs originatedfrom China [31–33] and one from Japan [34]. The three trials eval-uated 435 women with primary dysmenorrhea. Modified DSS wasused alone in three trials [31–33], and DSS was combined with diclofenac in one trial [34]. The details of the formula compositionsof DSS are listed in Table 2.DSS was compared with two types of analgesic, includingibuprofen [32,33] and fenbid [31]in three trials and one trial usedplacebo as a control [34]. The duration of the trials lasted fromtwo to three menstruation cycles. Three RCTs [31–33] used theresponse rate for each intervention by practitioner and it wasgenerally divided into four categories including (1) recovery, (2)marked improvement, (3) improvement, and (4) no change. Onetrial employed VAS to measure pain.