Colic is defined as "excessive crying." An infant with colic usually cries for more than three hours per day on more than three days per week. Colic is extremely common and occurs in up to 40 percent of all infants. It usually starts sometime between the third and sixth week after birth and ends when a baby is three to four months of age.

Signs and symptoms

Colic is more than excessive "normal" crying, at least in some infants. Colic differs from "normal" in the following ways:

● The crying episodes generally last a total of more than three hours per day.

● Each episode of colic has a clear beginning and end, and the onset is unrelated to what was happening before the episode started; the infant may have been happy, fussy, feeding, or even sleeping. The crying episode begins suddenly and often occurs in the evening hours.

● Colic episodes are more intense, louder, and higher pitched than "normal" crying. Infants with colic may sound as if they are in pain or are screaming.

● Infants with colic may have physical symptoms.

● Infants with colic are difficult or impossible to soothe, no matter what the parents do. There may be periods of quiet, but infants often remain fussy. Crying may end after the infant passes gas or a bowel movement.

When to see a doctor?

Excessive, inconsolable crying may be colic or an indication of an illness or condition that causes pain or discomfort. Schedule an appointment with your child's doctor for a thorough exam if your infant experiences excessive crying or other signs or symptoms of colic.

https://www.uptodate.com/contents/colic-excessive-crying-in-infants-beyond-the-basics

https://www.mayoclinic.org/diseases-conditions/colic/symptoms-causes/syc-20371074

https://patient.info/childrens-health/colic-in-babies-and-infants