Almost all babies go through a fussy period. When crying lasts for longer than about three hours a day and is not caused by a medical problem (such as a hernia or infection), it is called colic. This phenomenon occurs in almost all babies. The only thing that differs is the degree.

Colic usually strikes toward the end of a long day, when your baby is just about at the age when your sleep deprivation has really begun to set in. Your baby stops being the quiet, peaceful, miracle baby and begins screaming every evening. It is no wonder that parents can become frustrated, discouraged, and depressed.

The child with colic tends to be unusually sensitive to stimulation. Some babies experience greater discomfort from intestinal gas. Some cry from hunger, others from overfeeding. Some breastfed babies are intolerant of foods in their mothers' diets. Some bottle-fed babies are intolerant of the proteins in formula. Fear, frustration, or even excitement can lead to abdominal discomfort and colic. When other people around them are worried, anxious, or depressed, babies may cry more, which in turn makes those around them even more worried, anxious, or depressed.

About 20% of babies cry enough to meet the definition of colic. The timing varies, but colic usually affects babies beginning at about 3 weeks of age and peaking somewhere between 4-6 weeks of age.

Colic will not last forever! After about 6 weeks of age, it usually begins improving, slowly but surely, and is generally gone by 12 weeks of age. When colic is still going strong at 12 weeks, it's important to consider another diagnosis (such as reflux).

Colic frequently, but not always, begins at about the same time every day. For most infants the most intense fussiness is in the evening. The attack often begins suddenly. The legs may be drawn up and the belly distended. The hands may be clenched. The episode may last for minutes or hours. It often winds down when the baby is exhausted, or when gas or stool is passed.

In spite of apparent abdominal pain, colicky infants eat well and gain weight normally.

Colic is usually diagnosed by the parent's description of the crying. A careful physical exam is wise to be sure the baby does not have a hernia, intussusception, a hair tourniquet, a hair in the eye, or another medical problem that needs attention. If the diagnosis isn't clear, further testing may be needed.