Topic Overview

If you drink cow’s milk or eat dairy products that contain cow’s milk while breastfeeding, the milk protein and sugars are passed on to your baby. Protein and sugars from cow’s milk are also ingredients in most formulas. Some babies are sensitive to these proteins and sugars.

Cow’s milk protein sensitivity

Normally, milk protein poses no problems to a baby’s health or digestive system. But a small number of babies have reactions to a protein found in cow’s milk. Signs of cow’s milk protein sensitivity or intolerance include:

• Hives.
• Swelling of the face, tongue, mouth, or throat.
• Difficulty breathing, wheezing, or asthma.
• Abdominal (belly) pain.
• Vomiting.
• Diarrhea.

A formula-fed baby with suspected cow’s milk protein intolerance usually will be switched to a soy-based formula. But some babies have an intolerance to both milk protein and soy. These babies may need a hypoallergenic formula (such as Alimentum or Nutramigen).

If you are breastfeeding and you notice that your baby has signs of intolerance when you eat or drink dairy products, contact your baby’s doctor.

Cow’s milk sugar intolerance (lactase deficiency)

Some formula-fed babies develop problems similar to lactose intolerance in older children and adults. These babies do not produce enough of the lactase enzyme, which is needed to break down and digest the sugar in milk. In babies, this is a temporary problem. It does not mean that the child will be lactose intolerant as an adult.

Symptoms of lactase deficiency in infants include:

• A bloated stomach.
• Belly pain or cramps.
• Gas.

Babies who are exclusively breastfed do not develop a milk sugar intolerance. Breast milk contains lactase. So even if the baby has low levels of the enzyme, the amount of lactase contained in breast milk is enough to break down the milk sugars for proper digestion.

Medicines for lactose intolerance (such as Lactaid) will not help and should not be given to babies. Soy-based or hypoallergenic formulas that are lactose-free usually are given to replace regular formulas. Your doctor can help guide you about when to gradually try reintroducing regular formula.