Cow milk allergy (CMA) is an immunologically mediated adverse reaction to one or more cow milk proteins.

Cow milk allergy is one of the most common adverse food reactions in infancy and childhood: symptoms suggestive of cow milk allergy are seen in about 5-15% of infants, but the “true incidence” ranges from 2% to 7% when strict diagnostic criteria are used.

Cow milk is often the first major food protein ingested by formula-fed infants; a significant association between early neonatal exposure to cow milk and subsequent development of cow milk allergy has been documented. Even in exclusively breast fed infants reproducible clinical reactions to cow milk proteins in human milk have been reported in about 0.5%.

Cow milk allergy generally affects children less than three years: the mean age of onset is reported as between 3 months and 5 months. Children with immediate reaction following milk ingestion usually present earlier.

Recent evidence shows that cow milk sensitive enteropathy (CMSE) may persist or manifest itself initially in children of school age.