Abstract: We included nine trials with low risk of bias, which assessed paracetamol for the treatment of pain in 728 infants. Painful procedures studied included heel lance, assisted vaginal birth, eye examination for retinopathy of prematurity assessment and postoperative care. Results of individual studies could not be combined in meta-analyses as the painful conditions, the use of paracetamol and comparison interventions and the outcome measures differed. Paracetamol compared with water, cherry elixir or EMLA cream (eutectic mixture of lidocaine and prilocaine) did not significantly reduce pain following heel lance. The Premature Infant Pain Profile score (PIPP) within three minutes following lancing was higher in the paracetamol group than in the oral glucose group (mean difference (MD) 2.21, 95% confidence interval (CI) 0.72 to 3.70; one study, 38 infants). Paracetamol did not reduce "modified facies scores" after assisted vaginal birth (one study, 119 infants). In another study (n = 123), the Échelle de Douleur et d'Inconfort du Nouveau-Né score at two hours of age was significantly higher in the group that received paracetamol suppositories than in the placebo suppositories group (MD 1.00, 95% CI 0.60 to 1.40). In that study, when infants were subjected to a heel lance at two to three days of age, Bernese Pain Scale for Neonates scores were higher in the paracetamol group than in the placebo group, and infants spent a longer time crying (MD 19 seconds, 95% CI 14 to 24). For eye examinations, no significant reduction in PIPP scores in the first or last 45 seconds of eye examination was reported, nor at five minutes after the eye examination. In one study (n = 81), the PIPP score was significantly higher in the paracetamol group than in the 24% sucrose group (MD 3.90, 95% CI 2.92 to 4.88). In one study (n = 114) the PIPP score during eye examination was significantly lower in the paracetamol group than in the water group (MD −2.70, 95% CI −3.55 to 1.85). For postoperative care following major surgery, the total amount of morphine (µg/kg) administered over 48 hours was significantly less among infants assigned to the paracetamol group than to the morphine group (MD −157 µg/kg, 95% CI −27 to −288). No adverse events were noted in any study. The quality of evidence according to GRADE was low. The paucity and low quality of existing data do not provide sufficient evidence to establish the role of paracetamol in reducing the effects of painful procedures in neonates. Paracetamol given after assisted vaginal birth may increase the response to later painful exposures. Paracetamol may reduce the total need for morphine following major surgery, and for this aspect of paracetamol use, further research is needed.

Plain-language summary: We identified nine studies that reported comparisons in 728 infants of paracetamol versus placebo or other pain-reducing interventions. The literature search was updated in May 2016. Paracetamol for heel lance did not reduce pain compared with placebo (water or cherry elixir) or compared with EMLA cream (eutectic mixture of lidocaine and prilocaine). Paracetamol use was associated with a stronger response to pain than was seen with glucose. Paracetamol did not reduce pain in infants exposed to vacuum extraction or forceps at birth, and their response to a subsequent heel lance at two to three days of life was increased compared with placebo. For eye examination, paracetamol was effective in reducing pain compared with water in one study, but the pain response was stronger among paracetamol-treated infants than in infants given 24% sucrose. In infants treated with paracetamol and morphine compared with morphine alone, the total amount of morphine required during the first 48 hours following major surgery to the chest or the abdomen was less in the paracetamol group. Paracetamol did not significantly reduce pain during heel lance. Paracetamol following assisted birth may increase the response to later exposure to painful interventions. Paraetamol may reduce the total need for morphine following major surgery, and further research is needed into this aspect of paracetamol use. In general the studies were of good quality but the numbers of infants enrolled in the different studies were small. The overall quality of evidence was low.