Randomized, Blinded, Placebo-Controlled Evaluation of BioAmicus Complete

Inclusion Criteria: * The child's parents/guardians speak Russian, have been informed about the study's purpose, understand its essence, are aware of their rights, and have signed the informed consent form. * Diarrhea or constipation accompanied by colic and/or regurgitation (gastroesophageal reflux, GER). * Cutaneous manifestations of food allergy. * The child was born at term or preterm, but not before the 7th month of gestation. * Age at the time of parental informed consent: from 1 month to 4 months and 28 days. * The child is on breastfeeding, formula feeding, or mixed feeding. * The child has no other health conditions that would require a specialized diet. * The parents/guardians are able and willing to regularly complete the proposed observation diary form. Exclusion Criteria: * The child has a congenital pathology or any other conditions/diseases/clinical manifestations that may interfere with participation in the study. * Use of lactase supplements. * Use of other probiotic products, antibiotics, enteral antiseptics, antifungal, or antiprotozoal medications. * The child was born preterm (before the 7th month of gestation).