Objective: To explore the effects of partially hydrolyzed formula with synbiotics on the gastrointestinal symptoms and gut microbiota of toddlers with cow’s milk allergy history. Methods: We included toddlers with cow’s milk allergy who were treated in our hospital from December 2019 to January 2021

and recovered but have mild gastrointestinal symptoms. The participants were fed with partially hydrolyzed formula with synbiotics and followed up for three months. The toddlers’ gastrointestinal symptoms and feces were collected before and after the intervention

and the gut microbiota was tested by 16srDNA sequencing. Results: Thirty-eight toddlers aged 1-2 years old were included in the study

whose height and weight were significantly increased and symptom of functional constipation were significantly reduced after 3-month intervention. Other intestinal symptoms were not significantly changed and the formula was well tolerated. The proportion of Bifidobacterium was obviously increased

and the increase of Bifidobacterium was correlated with the improvement of constipation symptoms. Meanwhile

Pseudomonas and Moraxellaceae were significantly decreased after the intervention. Conclusion: Partially hydrolyzed formula with synbiotics could improve the gut microbiota composition and relieve functional constipation symptoms in toddlers with cow’s milk allergy history.