A spoonful of sugar really could make the medicine go down, researchers investigating infant vaccinations have discovered.

Babies fed a sugary solution cried for a shorter time after injections compared to those given water, a review of 14 studies involving more than 1500 infants found.

But it was difficult to conclude whether sugar solutions actually reduced pain because individual studies measured pain differently, according to researchers from the maternal and child health department at Jordan University of Science and Technology.

It is thought the sugar may help to reduce pain by triggering the release of pain-relieving chemicals in the body, or by contacting taste receptors that induce feelings of comfort.