Functional constipation (FC) definition as by the "Rome IV" diagnostic criteria as persistently difficult, infrequent, or seemingly incomplete defecation without evidence of a primary anatomic or biochemical cause This definition required at least two of six symptoms describing stool frequency, hardness, and size; faecal incontinence; or volitional stool retention, with the stipulation that organic causes of constipation are excluded by a thorough evaluation.

Children visiting outpatients clinic with defecation-related complaint account for 3% and 25% of pediatric gastroenterology consultations.

Functional constipation aetiology is still unclear. So is typically classified into normal transit constipation (NTC), slow transit constipation (STC), and defecatory or rectal evacuation disorders. The World Health Organization defines probiotics as “live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host”.