AbstractBackgroundCow's milk allergy (CMA) affects 2% of all children. This study investigatescomponent‐resolved diagnostics(CRD) to cow's milk proteins in children suspected of CMA, by correlating the level of CRD with outcome of the oral challenge. Furthermore, we evaluate the ability of serial CRD measurements to distinguish children with persistent CMA from children developing tolerance.MethodsWe included data from 78 children referred to the Allergy Centre during a 13‐year period. Results from oral food challenges including threshold, severity, and sensitization data (IgE antibodies to whole milk protein, IgE components toward milk and skin prick test (SPT)) were collected. The milk allergic children were re‐evaluated with sensitization data and rechallenges regularly.ResultsThirty‐nine children had negative first challenges, and 39 had positive first challenges. The positive group was rechallenged and separated into 3 groups depending on time to remission. At inclusion, children with persistent CMA had significantly larger size of SPT and higher levels of s‐IgE to milk and CRD compared to the other groups. SPT wheal size was significantly larger in children with persistent CMA compared to children outgrowing CMA. Furthermore, a correlation between s‐IgE level to cow's milk and casein and the severity of the allergic reaction elicited by food challenges was found.ConclusionOral food challenge cannot be replaced by s‐IgE to whole milk protein or milk components nor SPT in the diagnosis of CMA; however, high levels of milk components and s‐IgE to milk increase the risk of a long‐lasting or persisting CMA.