Acute food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated allergy and is characterized by repetitive profuse vomiting episodes, often in association with pallor, lethargy, and diarrhea, presenting within 1–4 h from the ingestion of a triggering food. In 2017, the international consensus guidelines for the diagnosis and management of FPIES were published. They cover all aspects of this syndrome, which in recent decades has attracted the attention of pediatric allergists. In particular, the consensus proposed innovative diagnostic criteria. However, the diagnosis of acute FPIES is still currently discussed because the interest in this disease is relatively recent and, above all, there are no validated panels of diagnostic criteria. We propose some ideas for reflection on the diagnostic and suspicion criteria of acute FPIES with exemplary stories of children certainly or probably suffering from acute FPIES. For example, we believe that new definitions should be produced for mild forms of FPIES, multiple forms, and those with IgE-mediated symptoms. Moreover, we propose two clinical criteria to suspect acute FPIES and to refer the child to the diagnostic oral food challenge.