Abstract: We included eight studies, involving 809 participants, comparing oral dipyrone 500 mg (143 participants), oral dipyrone 1000 mg (57 participants), and intramuscular dipyrone 2000 mg (35 participants) with placebo (236 participants). In addition to placebo, all studies used active controls (ibuprofen, paracetamol, aspirin, flurbiprofen, ketoprofen; 338 participants). Seven studies used the oral route of administration, and one study used the intramuscular route. The mean age ranged from 23 to 62 years. Six studies included both men and women, and two studies included only women. All the studies were small, but were otherwise of moderate to good quality. Over 70% of participants experienced our primary outcome of at least 50% pain relief over four to six hours with oral dipyrone 500 mg compared to 30% with placebo (five studies, 288 participants; NNT 2.4 (95% CI 1.8 to 3.1)) (moderate quality evidence). There were insufficient data to assess other doses or routes of administration of dipyrone. Fewer participants needed rescue medication within four to six hours with dipyrone 500 mg than with placebo (7% with dipyrone versus 34% with placebo; four studies, 248 participants) (low quality evidence). The data on numbers of participants experiencing any adverse event was inconsistently reported and no analysis was possible. No serious adverse events or adverse event withdrawals were reported (very low quality evidence). There were too few data to compare dipyrone directly with other active treatments. Based on very limited information, a single dose of dipyrone 500 mg provides good pain relief to about 70% of people treated, compared to about 30% with placebo. For every five people given dipyrone 500 mg, two people would experience this level of pain relief over four to six hours who would not have done with placebo, and fewer people would need rescue medication. We were unable to compare dipyrone directly with other active treatments, or to assess the effects of different doses or routes of administration, or the number of participants experiencing adverse events, because of insufficient data and inadequate reporting.

Plain-language summary: We searched medical databases for studies of dipyrone used to treat pain following surgery in adults and compared with placebo (a pretend treatment). The medicines could be given by mouth, into a vein, into a muscle, or into the rectum. The evidence is current to 11 August 2015. We found eight studies, involving 809 participants treated with dipyrone, placebo, and various other painkillers. The studies were all small, but otherwise of moderate to good quality. A single 500 mg dose of dipyrone provided effective pain relief (50% or more reduction in pain over four to six hours) for 7 in 10 (70%) participants, compared with 3 in 10 (30%) with placebo (five studies, 288 participants in the comparison; moderate quality evidence), and fewer participants need additional painkillers within four to six hours (7% with dipyrone, 34% with placebo; four studies, 248 participants; low quality evidence). There were too few data to compare dipyrone directly with other painkillers. There was too little information available to draw any conclusions about other doses and ways of giving dipyrone used in these studies, or about the number of people who had side effects. The studies reported no serious side effects or people withdrawing from the studies because of side effects, although not all studies provided information on these outcomes.