**5. Conclusions**

Chronic-milk-FPIES is a form of IgE-independent allergy. It is a rare syndrome, manifesting itself in the youngest infants after the introduction of milk formula. The symptoms, vomiting and diarrhea, quickly lead to severe growth retardation. Diagnosis is difficult due to the absence of eosinophilia in the blood tests, but the presence of leukocytosis and neutrophilia, which are indicative of infectious diseases. Treatment consists of a milk-free diet. Patients have multiple sensitizations to other foods, both in an IgE-dependent and IgE-independent mechanism. The foods that cause allergy symptoms are different in these two types of allergies. Furthermore, the transition of milk-induced FPIES to IgE-mediated milk allergy may occur in this disease. The occurrence of this transition in the course of OFC poses a risk of severe complications; therefore, milk provocation in these patients always requires intensive medical supervision.

**Author Contributions:** Conceptualization, G.C.-B. and K.B.; methodology, G.C.-B.; formal analysis, G.C.-B., K.B. and E.B.-P.; data curation, K.B., M.S. and E.B.-P.; writing—original draft preparation, G.C.-B. and K.B.; writing—review and editing, G.C.-B. and E.B.-P.; project administration, G.C.-B. and K.B.; funding acquisition, G.C.-B. and M.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** National Science Centre, Poland, grant No 2016/21/N/NZ7/03409 and statutory activities of Pomeranian Medical University in Szczecin (WNoZ-319-01/s/12/2013-2020).

**Institutional Review Board Statement:** Pomeranian Medical University Bioethics Committee No KB-0012/80/14.

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study. Patients consent was waived.

**Data Availability Statement:** The results of the tests are included in the records of the clinics where the children were treated.

**Conflicts of Interest:** The authors declare no conflict of interest.
