Colic is a disorder characterised by excessive, unsoothable crying, irritability or fussiness (Benninga et al., 2016, Zeevenhooven et al., 2017). The underlying reasons are still unclear, immaturity of the gastrointestinal and central nervous system, psychosocial causes, cow's milk allergy, microbial dysbiosis and altered gut hormone concentrations are still in discussion (Zeevenhooven et al., 2017, Savino et al., 2014).

According to Rome IV the diagnostic criteria for clinical purposes include all of the following (Benninga et al., 2016):
“1. An infant who is below five months of age when the symptoms start and stop
2. Recurrent and prolonged periods of infant crying, fussing, or irritability reported by caregivers that occur without obvious cause and cannot be prevented or resolved by caregivers
3. No evidence of infant failure to thrive, fever, or illness”