Milk intolerance in infants

Milk intolerance in infants

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A concerned mom shared her experience with other mothers about the likely causes of diarrhoea in children:

“When my daughter was two months old, she started having diarrhoea. I let this go on for a couple of days and then took her to our family doctor. The doctor told me that she had gastroenteritis (infectious diarrhoea). She was prescribed oral rehydration solution and Flagyl syrup.

“After a couple of days, she still wasn’t any better and I was at my breaking point. So, I scheduled an appointment with another doctor in order to get a second opinion. The new doctor that I now call my daughter’s paediatrician said she didn’t think that the baby had gastroenteritis. She said that she was likely to be lactose intolerant and had colic.

“She told us that when a baby is developing intolerance to cow’s milk, a symptom of that is diarrhoea. So, she advised us to change her baby formula. We did and, immediately, the diarrhoea stopped.”

Lactose (milk) intolerance happens when the body cannot break down a sugar called lactose, which is present in all milk – from breast milk, to dairy (cow) milk and other dairy products.

Lactose makes up around seven per cent of breast milk, similar to the amount in infant formula. Lactose provides around 40 per cent of baby’s energy needs, helps absorb calcium and iron, and helps ensure healthy development.

Usually, the enzyme, lactase, which is produced in the small intestine, changes lactose into glucose and galactose – sugars that are more easily absorbed. Sometimes, babies don’t produce enough lactase to break down all the lactose, so the unabsorbed lactose passes through the intestine without being digested. Undigested lactose irritates the intestine and causes a build-up of wind and diarrhoea.

Most children or adults who are diagnosed with lactose intolerance can digest small amounts of lactose, which would not cause symptoms.


Primary lactose intolerance happens when babies are born with no lactase enzymes at all. This is genetic and extremely rare. It is a medical emergency and the baby would need a special diet from soon after birth in order to thrive.

Secondary lactose intolerance can occur if a child’s digestive system is disrupted by any illness that affects healthy production of enzymes like lactase; or if there is not enough lactase being produced. Illnesses that might lead to secondary lactose intolerance include tummy bugs that cause gastroenteritis.

Sometimes, lactose intolerance is confused with other digestive problems, such as food allergy or lactose overload. This is because these conditions have similar symptoms. Food allergies and lactose overload are not the same as lactose intolerance, and do not affect a baby’s production of lactase.

Lactose overload

Lactose overload also causes all the symptoms similar to lactose intolerance, but it is not the same as lactose intolerance. Lactose overload occurs when a baby consumes large amounts of lactose at one time and cannot break it all down. The condition can occur when bottle-fed babies drink a lot of milk. Again, babies who are being weaned on too much milk may have similar conditions. Mothers have a natural oversupply of breast milk in their baby’s early weeks.


The symptoms of lactose intolerance and lactose overload are similar and are listed as: pain, wind, swelling of the tummy, crankiness, failure to settle at feeding times, coming on and off the breast, failure to gain weight, diarrhoea, frothy green stools, perianal excoriation (redness and peeling of the buttocks) and an irritable baby who may pass wind often.

Lactose intolerance doesn’t cause vomiting, but food allergies do.

Diagnosing lactose intolerance

Clinitest tablet: This is usually deployed when a small amount of stool is mixed with water, and then a special tablet is added and checked for colour change. This is mostly used when temporary lactose intolerance is suspected after gastroenteritis.

Hydrogen breath test: This is used to test the amount of hydrogen gas in the child’s breath. Lactose-intolerant children will have higher levels of hydrogen in their breath, because of the process of fermentation in the gut (when bacteria feed on the lactose that hasn’t been broken down).

Elimination diet: This involves removing foods containing lactose from the child’s diet to see whether symptoms improve. If the symptoms come back once the foods are reintroduced, lactose intolerance is most likely the cause of the problem.

Stool PH/acidity test: This test, used in infants and young children, measures the amount of acid in the stool. It will reveal the presence or otherwise of lactic acid and glucose produced by undigested lactose and other substances.


Treatment for lactose intolerance depends on the cause. Primary lactose intolerance is an emergency. It requires the attention of a doctor, paediatrician or nutritionist.

For secondary lactose intolerance caused by gastroenteritis, using Lactaid drops that contain the enzyme lactase may help. This is not readily available in Nigeria, though.

Alternate breastfeeding with lactose-free or soy-based infant formula, which are readily available in Nigeria, can also be deployed. For serious condition, the baby may be weaned from the formula for a while.

In the case of perianal excoriation, the redness, cuts or abrasions on the baby’s buttocks due to acidity of the lactose may be treated with good protective cream.


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