BioAmicus Complete for Functional Gastrointestinal Symptoms in Infants Aged 0 to 24 Months

Inclusion Criteria: * Age 0-24 months at enrollment. * Infant has clinician-assessed functional gastrointestinal symptoms (e.g., colic/irritability, regurgitation, constipation, loose stools), judged suitable for study participation. * Parent or legal guardian provides written informed consent and agrees to comply with study procedures (questionnaires/diaries and sample collection, if applicable). * Caregivers agree to avoid other probiotic products during the study period, except as directed by the study team. Exclusion Criteria: * Major congenital gastrointestinal anomalies or known chronic gastrointestinal diseases requiring ongoing prescription therapy (e.g., Hirschsprung disease, inflammatory bowel disease, short-bowel syndrome). * Clinically unstable condition or severe/critical illness that could interfere with participation or safety in the opinion of the investigator. * Known or suspected primary or secondary immunodeficiency, or current immunosuppressive therapy. * History of severe allergy or hypersensitivity to components of the investigational product. * Recent use of systemic antibiotics within 14 days prior to baseline, or use of probiotic supplements within 14 days prior to baseline (per protocol). * Participation in another interventional clinical trial within 30 days prior to enrollment or during the study. * Any condition that, in the investigator's judgment, would make the participant unsuitable for the study or confound outcome assessments.