Background Infantile colic is a common disorder in the first months of life, affecting somewhere between 4% and 28% of infants worldwide, depending on geography and definitions used. Although it is self limiting and resolves by four months of age, colic is perceived by parents as a problem that requires action. Pain-relieving agents, such as drugs, sugars and herbal remedies, have been suggested as interventions to reduce crying episodes and severity of symptoms. Objectives To assess the effectiveness and safety of pain-relieving agents for reducing colic in infants younger than four months of age. Search methods We searched the following databases in March 2015 and again in May 2016: CENTRAL, Ovid MEDLINE, Embase and PsycINFO, along with 11 other databases. We also searched two trial registers, four thesis repositories and the reference lists of relevant studies to identify unpublished and ongoing studies. Selection criteria We included randomised controlled trials (RCTs) and quasi-RCTs evaluating the effects of pain-relieving agents given to infants with colic. Data collection and analysis We used the standard methodological procedures of The Cochrane Collaboration. Main results We included 18 RCTs involving 1014 infants. All studies were small and at high risk of bias, often presenting major shortcomings across multiple design factors (e.g. selection, performance, attrition, lack of washout period). Three studies compared simethicone with placebo, and one with Mentha piperita; four studies compared herbal agents with placebo; two compared sucrose or glucose with placebo; five compared dicyclomine with placebo; and two compared cimetropium - one against placebo and the other at two different dosages. One multiple-arm study compared sucrose and herbal tea versus no treatment. Simethicone. Comparison with placebo revealed no difference in daily hours of crying reported for simethicone at the end of treatment in one small, low-quality study involving 27 infants. A meta-analysis of data from two cross-over studies comparing simethicone with placebo showed no difference in the number of of infants who responded positively to treatment (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.73 to 1.23; 110 infants, low-quality evidence). One small study (30 participants) compared simethicone with Mentha piperita and found no difference in crying duration, number of crying episodes or number of responders. Herbal agents. We found low-quality evidence suggesting that herbal agents reduce the duration of crying compared with placebo (mean difference (MD) 1.33, 95% CI 0.71 to 1.96; three studies, 279 infants), with different magnitude of benefit noted across studies (I-2 = 96%). We found moderate-quality evidence indicating that herbal agents increase response over placebo (RR 2.05, 95% CI 1.56 to 2.70; three studies, 277 infants). Sucrose. One very low-quality study involving 35 infants reported that sucrose reduced hours spent crying compared with placebo (MD 1.72, 95% CI 1.38 to 2.06). Dicyclomine. We could consider only one of the five studies of dicyclomine (48 infants) for the primary comparison. In this study, more of the infants given dicyclomine responded than than those given placebo (RR 2.50, 95% CI 1.17 to 5.34). Cimetropium bromide. Data from one very low-quality study comparing cimetropium bromide with placebo showed reduced crying duration among infants treated with cimetropium bromide (MD -30.20 minutes per crisis, 95% CI -39.51 to -20.89; 86 infants). The same study reported that cimetropium increased the number of responders (RR 2.29, 95% CI 1.44 to 3.64). No serious adverse events were reported for all of the agents considered, with the exception of dicyclomine, for which two of five studies reported relevant adverse effects (longer sleep 4%, wide-eyed state 4%, drowsiness 13%). Authors' conclusions At the present time, evidence of the effectiveness of pain-relieving agents for the treatment of infantile colic is sparse and prone to bias. The few available studies included small sample sizes, and most had serious limitations. Benefits, when reported, were inconsistent. We found no evidence to support the use of simethicone as a pain-relieving agent for infantile colic. Available evidence shows that herbal agents, sugar, dicyclomine and cimetropium bromide cannot be recommended for infants with colic. Investigators must conduct RCTs using standardised measures that allow comparisons among pain-relieving agents and pooling of results across studies. Parents, who most often provide the intervention and assess the outcome, should always be blinded.
