Inclusion Criteria:  Age 0-12 years  Suspected of cow's milk allergy with one or more of the following complaints after intake of cow's milk:  angioedema urticaria sneezing and rhinitis <2 hours after feeding sensation of swelling in the throat and/or difficulty swallowing <2 hours after feeding voice change/hoarseness <2 hours after feeding cough <2 hours after feeding wheezing and/or shortness of breath <2 hours after feeding loss of consciousness <2 hours after feeding vomiting or abdominal pain or diarrhoea <2 hours after feeding in children <4 years only in combination with IgE-mediated complaints in other tracts Placed on a waiting list for a hospital food challenge test Blood draw for cow's milk sIgE and BAT < 3 months before the food challenge test. This blood draw will be simultaneously scheduled with a blood draw for regular diagnostics. Signed informed consent parents/guardians  Exclusion Criteria:  Age > 12 years Suspicion of Food Protein-Induced Enterocolitis Syndrome (FPIES) Eosinophilic esophagitis due to a cow's milk allergy Suspected cow's milk allergy <4 years with crying and/or agitation and/or eczema and/or abdominal pain and/or failure to thrive and/or blood loss per anum and/or diarrhoea and/or reflux and/or vomiting as the only manifestation of the allergy without IgE-mediated symptoms in another organ system Systemic immunosuppressant use Other underlying chronic conditions (immunological, oncological, chromosomal abnormalities).