Abstract: We included one unpublished and seven published studies (total of 808 participants); four more studies and 478 more participants than the 2011 review. Six trials included young children aged one to four years receiving sucrose or candy lollypops for immunisation pain compared with water or no treatment. Usual care included topical anaesthetics, upright parental holding, and distraction. All studies were well designed blinded RCTs, however, five of the six studies had a high risk of bias based on small sample sizes. Two studies included school-aged children receiving sweet or unsweetened chewing gum before, or before and during, immunisation and blood collection. Both studies, conducted by the same author, had a high risk of bias based on small sample sizes. Results for the toddlers/pre-school children were conflicting. Duration of cry, using a random-effects model, was not significantly reduced by sweet taste (six trials, 520 children, WMD -15 seconds, 95% CI -54 to 24, I2 = 94%). Composite pain score at time of first needle was reported in four studies (n = 121 children). The scores were not significantly different between the sucrose and control group (SMD -0.26, 95% CI -1.27 to 0.75, I2 = 86%). A Children's Hospital of Eastern Ontario Pain Scale score > 4 was significantly less common in the sucrose group compared to the control group in one study (n = 472, RR 0.55, 95% CI 0.45 to 0.67; RD -0.29, 95% CI -0.37 to -0.20; NNTB 3, 95% CI 3 to 5; tests for heterogeneity not applicable. For school-aged children, chewing sweet gum before needle-related painful procedures (two studies, n = 111 children) or during the procedures (two studies, n = 103 children) did not significantly reduce pain scores. A comparison of the Faces Pain Scale scores in children chewing sweet gum before the procedures compared with scores of children chewing unsweetened gum revealed a WMD of -0.15 (95% CI -0.61 to 0.30). Similar results were found when comparing the chewing of sweet gum with unsweetened gum during the procedure (WMD 0.23, 95% CI -0.28 to 0.74). The Colored Analogue Scale for children chewing sweet gum compared to unsweetened gum before the procedure was not significantly different (WMD 0.24 (-0.69 to 1.18)) nor was it different when children chewed the gum during the procedure (WMD 0.86 (95% CI -0.12 to 1.83)). There was no heterogeneity for any of these analyses in school-aged children (I2 = 0%). Based on the eight studies included in this systematic review update, two of which were subgroups of small numbers of eligible toddlers from larger studies, and three of which were pilot RCTs with small numbers of participants, there is insufficient evidence of the analgesic effects of sweet tasting solutions or substances during acutely painful procedures in young children between one and four years of age. Further rigorously conducted, adequately powered RCTs are warranted in this population. Based on the two studies by the same author, there was no evidence of analgesic effects of sweet taste in school-aged children. As there are other effective evidence-based strategies available to use in this age group, further trials are not warranted. Despite the addition of four studies in this review, conclusions have not changed since the last version of the review.

Plain-language summary: Study characteristics: We found six studies focused on young children aged one to four years; two of these studies were included in the original review and four were new studies. The two studies included in the original review used a low concentration of sucrose, just 12%, which is not considered sweet enough for the pain reducing effects. Three of the four new studies were small pilot studies, conducted to inform full trials, and only one study of sweet solutions in young children included large numbers of children. When we compared results of all six studies, only two showed that sugar water (sucrose) reduced pain during injections. However, the four studies that showed no effect all included small numbers of children, therefore they were not considered large enough to detect significant differences in pain. Further well conducted trials with large enough numbers of young children are needed to work out if sweet taste effectively reduces their pain and distress during needles. For older school-aged children, there were two studies published by the same author, both of which were included in the original review. Neither study showed that sweet taste helped to reduce pain. As other studies show that strategies such as distraction and topical anaesthetics can effectively reduce needle pain in school-aged children, further studies of sweet taste for pain management in school-aged children are not warranted. Study funding sources: Of the six studies including young children, two did not acknowledge receipt of research funding. For the remaining four: a state-wide nursing fund supported two of the pilot studies, an internal research institute provided support for the remaining pilot study and another study was supported in part by a Maternal and Child Health grant. The two studies including school-aged children, conducted by the same author, were supported by a grant from the Canadian Institutes of Health Research.