Synbiotics Cohort Study

Inclusion Criteria: * Aged \<13 months * Confirmed or suspected CMA- based on healthcare professional (HCP) judgement * At baseline, parent(s) must already be exclusively or partially formula feeding their child (with a hypoallergenic or non-hypoallergenic formula) or have already made the decision to start exclusively or partially formula feeding * Recently prescribed a hypoallergenic formula containing synbiotics Exclusion Criteria: * Exclusively breastfed infants * Primary lactose intolerance * Enterally fed infants * Premature infants (born \<37 weeks) with a corrected age of less than 1 month * Infants with contraindications to the use of hyopallergenic formula containing synbiotics * Major hepatic or renal dysfunction * Investigator concern around the ability of family to comply with protocol and requirements of study