CoMiSS™ was first developed in 2015 by the Expert Consensus Panel, mostly considering theoretical concepts and existing clinical practice. Since its conception, CoMiSS™ has been used globally and therefore data is now available from 25 original clinical trials using the tool, which have been reviewed in a recent publication. During 2021 and 2022 the Expert Consensus Panel, of whom 7 were part of the first consensus group, reviewed, debated and discussed the new evidence available to identify if CoMiSS™ could be improved and updated. The panel concluded that that the cut-of should be lowered from ≥12 to ≥10. Since the Brussels Infant and Toddlers Stool Scale (BITSS) was developed for non-toilet trained children, the Bristol Stool Scale was changed to the BITSS without changing the impact of stool composition on CoMiSS™. Further guidance is also provided for those infants for whom the tool should not be used who have severe and life-threatening symptoms clearly indicating CMA. CoMiSS™ remains an excellent tool to increase the awareness of healthcare professionals to the possibility that the symptoms presented by infants are related to cow’s milk. It is not a diagnostic tool and therefore CMA diagnosis can only be confirmed by an elimination diet followed by an oral food challenge.