Cow's milk allergy (CMA) is one of the most common food allergies world-wide. The emergence of online CMA symptom questionnaires, aimed at parents and/or healthcare professionals (HCP), may raise awareness about the possible diagnosis of CMA, but also increases the risk for overdiagnosis leading to unnecessary dietary restriction impacting on growth and nutrition. This publication sets out to establish the availability of these CMA symptom questionnaires and critically assesses the development and validity.Thirteen HCP working in the field of CMA, from different countries, were recruited to participate. A combination of a Pubmed and CINAHL literature and online review using the Google search engine in English language was used. Symptoms in the questionnaires were assessed, using the European Academy for Allergy and Clinical Immunology guidelines for food allergy. Following the assessment of both the questionnaires and literature, the authors followed the modified Delphi approach to generate consensus statements.Six hundred and fifty-one publications were identified, of which 29 were suitable for inclusion, with 26 being associated with the Cow's Milk-Related Symptoms Score. The online search yielded 10 available questionnaires: 7/10 were sponsored by formula milk companies and 7/10 were aimed at parents and three at HCP. Following the assessment of data, 19 statements were generated in two rounds of anonymous voting reaching 100% agreement.Online CMA questionnaires, available to parents and HCP's, are varied in symptoms, and most were not validated. The overarching consensus generated from authors is that these questionnaires should not be used without the involvement of HCP.