Colic is persistent, unexplained crying in a healthy baby between two weeks and five months of age.

Colic, which is not a disease, affects 10-20% of all infants. It is more common in boys than in girls and most common in a family's first child. Symptoms of colic usually appear when a baby is 14-21 days old, reach a crescendo at the age of three months, and disappear within the next eight weeks. Episodes occur frequently but intermittently and usually begin with prolonged periods of crying in the late afternoon or evening. They can last for just a few minutes or continue for several hours. Some babies who have colic are simply fussy. Others cry so hard that their faces turn red, then pale.

No one knows what causes colic. The condition may be the result of swallowing large amounts of air, which becomes trapped in the digestive...