The most recent diagnostic criteria for infantile colic are from the Rome IV committee. They are: recurrent and prolonged periods of crying or fussing (i.e., not crying, but not content) without an obvious cause, and without evidence of failure to thrive or illness, in infants younger than 5 months of age.[1][2]
Additionally, there is a set of criteria from 1954 that is still widely used. The Wessel criteria, or “rule of threes,” defines colic as attacks of irritability, fussing, or crying lasting 3 or more hours per day on 3 or more days per week for 3 or more weeks in an otherwise healthy baby aged 2 weeks to 4 months.[3]
Abdominal distension, fever, and prolonged lethargy are seldom found in simple colic and require investigation to rule out other significant disease.[4]