Doctors are not sure what causes colic. Some believe it is due to a milk allergy, but doctors now believe this is rarely the case since breastfed babies often get colic too. And, approximately 35 percent of infants who are allergic to milk-based formulas are also allergic to soy milk-based formulas. It is, however, possible, for mother's to pass on a milk allergy by breastfeeding because a more recent discovery concluded that milk allergens enter the milk of a breastfeeding mother and irritate a baby's intestines resulting in colic. If your baby is colicky and you are breastfeeding, it may be a worthy test to go dairy-free for while.
Colic is probably not the result of gas either, which was another previous thought. Research now suggests that colicky babies get gas because they are swallowing too much air while they are feeding or crying.
More recent evidence suggests that colic occurs when food moves too quickly or too slowly through the baby's digestive system. It is also thought that colic can be the result of the baby's individual temperament; which means that some babies just take a little bit longer to get adjusted to living outside of the womb, or that some babies have an undiagnosed reflux disease.
Others speculate that colic could be the result of one or more of the following:
Ear Infections – Signs that your baby may have an ear infection include: pain when they are lying down, cold symptoms, and not sleeping well. A thorough examination of your baby's ears should be part of a colic checkup.
Pediatric Regurgitation Syndrome (PRS) – Also called gastrointestinal reflux, or in more severe cases Gastroesophageal reflux (GERD), PRS is a recent discovery as a medical cause of colic. When food passes through your baby's throat and into the stomach, the stomach contracts and pushes whatever is already in there into the intestines. In some babies this does not work properly – when the stomach contracts, some of the food is pushed back up into the esophagus and, in some cases, even out of the mouth. The stomach acid irritates the esophagus and cause heartburn. Signs that reflux may be contributing to colic are: frequent spitting up after eating, colicky episodes that occur shortly after eating, frequent awakening at night as if in severe pain, and colic that is just not going away.
Urinary Tract Infections – A urinary tract infection is one of the most serious and most hidden causes of colic. These infections are very subtle, often lasting for a few weeks before they are detected. Urinary tract infections can cause kidney damage if left untreated. If you suspect this to be the case, take your baby to the doctor for a urinalyses.
Skin Rashes – Skin rashes may also be a cause of colic. Eczema, rashes caused by allergies, and diaper rashes may be the reason why the baby is colicky. Diaper rash that is particularly hard on baby is the raw rash that looks almost like a skin burn which is caused by acid stools from diarrhea. Bathe your baby in baking soda (one tablespoon in a couple of inches of water in baby's bath) to help soothe it.
Constipation – Constipation is another possible reason for the colic that is rarely looked at. If your baby strains or turns red a lot when they have a bowel movement, and if the stool looks hard, or if it is accompanied by a few drops of blood droplets or if they have a tense, gas-filled (hard) tummy, your baby may be constipated. Consult your pediatrician.
Since no one can pinpoint one primary reason for colic, it is best to create a log of when your baby is the most colicky and note feeding times, which foods were fed, etc. then take the log to your pediatrician for recommendations.