RÉSUMÉ
Objective To treat the patients with primary dysmenorrhea by puncturing Shiqizhui (EX-B8) and observe the change and regularity of the analgesic effect with different needle-retaining time, for providing evidence for the optimal needle-retaining time. Method Ninety eligible subjects with primary dysmenorrhea were randomized into a 20 min group of 30 cases, a 30 min group of 30 cases, and a blank control group of 30 cases. Visual Analogue Scale (VAS) was used to observe the change before and after intervention with the time, and to compare the intergroup differences. Result The acupuncture groups started to show analgesic effect 10 min after needling, and the effect increased with the needle-retaining time (P＜0.05);the therapeutic efficacy of the 30 min group was significantly superior to that of the 20 min group (P＜0.01). Conclusion Acupuncture at Shiqizhui can produce a real-time analgesic effect for patients with primary dysmenorrhea, and retaining the needle for 30 min is superior to 20 min.