Lactose intolerance is the inability to digest the natural sugar, lactose, found in milk and milk products. This is caused by a deficiency in the enzyme lactase. Lactase is produced in the small intestine and breaks down lactose into simpler sugars that are absorbed into the bloodstream. When lactose is not broken down, it can not be absorbed properly and the resulting undigested lactose creates gas and liquid that can result in diarrhea.


The main cause of lactase deficiency often begins in young children and causes a slow decline in the production of lactase. Symptoms may not appear until early adulthood. Other reasons the body may not produce sufficient lactase include injury, infection, or disease in the small intestine, and developmental deficiency seen in premature infants. Both of these types usually resolve themselves in time after treatment, healing, and maturing.


Symptoms appear between 30 minutes and two hours of consuming milk, milk products, or processed foods containing lactose. These symptoms include bloating, abdominal pain, diarrhea, gas, and nausea.

Screening and Diagnosis

A medical and family history is taken to determine the pattern of symptoms. Since the symptoms of lactose intolerance are similar to other GI conditions, tests may be ordered to confirm the diagnosis.


When the diagnosis is confirmed, lactose intolerance can be treated by avoiding lactose in all forms. This requires the patient to become an avid label reader of common foods, because many packaged products contain lactose. If your child is diagnosed with lactose intolerance, it is important to work closely with the doctor to assure proper nutrition for growth and development. There are products that contain lactase, that taken with meals containing lactose, help digest the food and reduce symptoms. Check with your doctor before taking these over the counter products, as they are not be appropriate for young children or pregnant and breastfeeding women.