Probiotics do nothing to help soothe babies with colic, according to the largest research trial to date.
Previous studies have suggested some benefit from giving infants probiotic drops, but they were flawed, and the latest stud set out to test the theory of whether probiotics would help breastfed and formula-fed babies with colic.
The results showed probiotics had no effect on reducing periods of crying or fussing among the babies, who were all under three months old.
Colic is a term used to describe infants who cry a lot but who are otherwise healthy and well fed.
The causes of colic are unknown although some theories suggest indigestion, trapped wind or a temporary sensitivity to proteins or sugars in breast or formula milk.
The condition affects up to one in five babies and usually begins within the first few weeks of life but often stops by the time the baby is four months old.
In most cases, the most intense period of crying occurs in the late afternoon or evening and usually lasts for several hours.
The team of experts in Australia, looked at several outcomes including duration of crying or fussing, how well the babies slept and how parents were coping.
At one month into the study, babies in the probiotic group actually cried or fussed 49 minutes more than those in the placebo group. No differences were observed on all the other outcomes.