This systematic review summarises evidence regarding oral nutritional supplement (ONS) use in children with, or at risk of, faltering growth (FG). Ten randomised controlled trials (RCTs), compared changes in outcomes amongst children receiving ONS versus control were included. Overall, 1116 children (weighted mean (WM) age 5 years
n658 (59%) male) were recruited, of which 585 (52%) received ONS (WM intake contribution 412 kcal, 16.3 g protein, 395 ml) for 116 days (WM). ONS use was associated with significantly greater gains in weight (mean difference (MD) 0.4 kg, 95% CI [0.36, 0.44]) and height (MD 0.3 cm, 95% CI [0.03, 0.57]), likely related to improvements in nutritional intake. Mean compliance to prescribed dose was 98%. Data suggested an association between ONS use and reduced infections. Further research is warranted to establish ONS dosage and effects upon other outcomes. This review provides evidence to support use of ONS in the management of children with, or at risk of, FG.