This is a systematic review of RCTs looking at the analgesic efficacy of oral sweet solutions compared to water or no treatment in infants (1-12 months) during immunisation. There is already a large body of evidence that sucrose or glucose reduces the pain of venepuncture in newborns and the authors conclude that it also works in the older infants though the effects are more moderate. They suggest that healthcare professionals should consider using sucrose or glucose before and during immunisation.
Harrison D et al. Arch Dis Child 2010;95:406-413. doi:10.1136/adc.2009.174227

(From the July 2010 Emergency Department edition of Paediatric Pearls – get the whole PDF here)