Abstract: We included 42 RCTs (4640 women). Acupuncture or acupressure was compared with a sham/placebo group, medication, no treatment or other treatment. Many of the continuous data were not suitable for calculation of means, mainly due to evidence of skew. 1. Acupuncture studies Acupuncture versus sham or placebo control (6 RCTs) Findings were inconsistent and inconclusive. However, the only study in the review that was at low risk of bias in all domains found no evidence of a difference between the groups at three, six or 12 months. The overall quality of the evidence was low. No studies reported adverse events. Acupuncture versus NSAIDs Seven studies reported visual analogue scale (VAS) pain scores, but were unsuitable for pooling due to extreme heterogeneity (I² = 94%). In all studies the scores were lower in the acupuncture group, with the mean difference varying across studies from 0.64 to 4 points on a VAS 0 - 10 scale (low-quality evidence). Four RCTs reported rates of pain relief, and found a benefit for the acupuncture group (OR 4.99, 95% CI 2.82 to 8.82, 352 women, I² = 0%, low-quality evidence). Adverse events were less common in the acupuncture group (OR 0.10, 95% CI 0.02 to 0.44, 4 RCTs, 239 women, 4 trials, I² = 15%, low-quality evidence). Acupuncture versus no treatment Data were unsuitable for analysis, but pain scores were lower in the acupuncture group in all six studies reporting this outcome. The quality of the evidence was low. No studies reported adverse events. 2. Acupressure studies No studies of acupressure reported adverse events. Acupressure versus sham or placebo control Data were unsuitable for pooling, but two studies reported a mean benefit of one to three points on a 0 - 10 VAS pain scale. Another four studies reported data unsuitable for analysis: all found that pain scores were lower in the acupuncture group. No studies reported adverse events. The quality of the evidence was low. Acupressure versus NSAIDs One study reported this outcome, using a 0 - 3 pain scale. The score was higher (indicating more pain) in the acupressure group (MD 0.39 points, 95% CI 0.21 to 0.57, 136 women, very low-quality evidence). Acupressure versus no treatment There was no clear evidence of a difference between the groups on a VAS 0 - 10 pain scale (MD -0.96 points, 95% CI -2.54 to 0.62, 2 trials, 140 women, I² = 83%, very low-quality evidence). There is insufficient evidence to demonstrate whether or not acupuncture or acupressure are effective in treating primary dysmenorrhoea, and for most comparisons no data were available on adverse events. The quality of the evidence was low or very low for all comparisons. The main limitations were risk of bias, poor reporting, inconsistency and risk of publication bias.

Plain-language summary: We have included 42 trials of acupuncture and acupressure compared to a control (sham/placebo, medication, Chinese herbs, no treatment or usual care) in a total of 4640 women of reproductive age with period pain. Twenty-two studies were undertaken in China. Eight studies were undertaken in Iran, four studies in Taiwan, two studies in Korea, and one each in Australia, Germany, Hong Kong, Thailand, Turkey, and the USA.The evidence is current to September 2015. There was insufficient evidence to demonstrate whether or not acupuncture or acupressure is effective in treating primary dysmenorrhoea, and for most comparisons no information was available on adverse events. The quality of the evidence was low or very low for all comparisons. The main limitations were risk of bias, poor reporting, inconsistency and risk of publication bias.