My baby cries all the time. Could it be colic?

Colic is the term used to describe uncontrollable crying in an otherwise healthy baby. If your baby is younger than 5 months old and cries for more than three hours in a row on three or more days a week for at least three weeks (phew!), he's considered colicky. Colic isn't a disease and won't cause your baby any long-term harm, but it's a tough thing to go through for both babies and their parents.

If your baby is colicky, find more than 20 sanity-saving tips to help you deal with it in our article about coping with colic.

What are the signs of colic?

Colic most often shows up when a baby is 2 or 3 weeks old (or two or three weeks after his due date if he's a preemie).

Babies normally cry when they're wet, hungry, frightened, or tired, but a baby with colic cries excessively, often at the same time of day (usually in the late afternoon or evening). If your baby is colicky, you may notice that his cries at this time are louder and higher pitched than his normal crying and that the episodes start and end suddenly.

Your colicky baby may also show signs of a gassy tummy. Gas doesn't cause colic, but he might be extra gassy because a baby with colic often swallows air when he cries. You may notice that your colicky baby clenches his fingers, arches his back, becomes flushed, and alternately extends or pulls up his legs and passes gas as he cries. He may sometimes feel better after passing gas or having a bowel movement.

How long will this last?

Thankfully, there's a light at the end of the tunnel. Colic tends to peak around 6 weeks, and then improves significantly between 3 and 4 months. By 4 months of age, 80 to 90 percent of infants are over colic. The remaining small percentage might take another month.

Yes, that's a long tunnel. In the meantime, learn how to comfort your baby as best you can and ask for help when you need it. Caring for a colicky baby can be very stressful, and you need to take regular breaks to maintain your own well-being. Have your partner or a friend or relative take over while you go for a walk or let loose with a good cry yourself when you need to.

Why are some babies colicky?

Colic is one of the great mysteries of baby life. Experts estimate that between 8 and 40 percent of babies become colicky. The condition is equally common among firstborn and later-born babies, among boys and girls, and among breastfed and formula-fed infants. No one knows why some babies are more prone to it than others, but theories abound. And there may well be more than one cause.

We do know that babies born to mothers who smoked during pregnancy or postpartum are at increased risk of colic (though this risk is reduced if the baby is breastfed).

Some experts believe that long bouts of colicky crying are a physical release for sensitive babies. By the time evening rolls around, they say, these babies just can't handle any more sights, sounds, or sensations, and so they become distraught and cry.

Another theory is that colic is sometimes caused by an imbalance of healthy bacteria in the intestines. Studies have shown that infants with colic have different intestinal microflora than infants who don't suffer from colic. Treatment with probiotics (specifically Lactobacillus reuteri) has been shown to help with colic symptoms in some babies. Ask your doctor for a specific probiotic recommendation.

Should I take my baby to the doctor if I think he has colic?

Yes, it's a good idea to talk with a doctor about your baby's crying. She can rule out other potential causes, like intestinal problems or urinary infections, and she'll want to check that your baby is feeding and growing normally. She'll also help you determine the best course of action for your baby if he does have colic.

And if your baby has other symptoms – like fever, vomiting, or bloody stools – call his doctor immediately. These symptoms are not due to colic.