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