Milk Protein Intolerance Symptoms

By Shelley Frost
A pediatrician examining a newborn baby on a table.
A pediatrician examining a newborn baby on a table.

Milk protein intolerance causes symptoms in the digestive system, but it can also cause skin reactions and irritability. About 2 to 3 percent of babies deal with milk protein intolerance, according to GI Kids, an educational website from the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. Recognizing the symptoms enables you to make dietary changes that alleviate the uncomfortable side effects of milk protein intolerance in your baby.

General Milk Intolerance Symptoms

Casein and whey -- two proteins in milk -- cause the symptoms if your baby has a milk intolerance. Your baby may react to one or both of the proteins. The reaction can happen not only with cow's milk, but also goat and sheep milk and sometimes soy milk proteins. A milk protein intolerance is different than lactose intolerance, which happens when the body is unable to digest sugar lactose. Lactose intolerance rarely occurs in babies.

The reaction to milk protein manifests in different ways. Digestive symptoms include vomiting, gagging, and loose stools, sometimes with blood. Potential skin symptoms are hives, eczema and bumps on the skin. Behavioral changes are also a potential sign. Your baby may become irritable, cry frequently or refuse to eat.

Formula Reactions

Soy or cow's milk forms the base of most infant formula. If your baby is formula-fed and has a milk protein intolerance, she may start showing symptoms after taking bottles. Extensively hydrolyzed formulas are an option for formula-fed infants. The proteins in this type of formula are broken down for easier digestion without a reaction. About 90 percent of infants with milk protein intolerance respond well to extensively hydrolyzed formulas, according to the GI Kids website. If symptoms don't go away after two to four weeks on this type of formula, an amino-acid formula may be necessary. Talk with your pediatrician about which formula might work best for your baby.

Breast Milk Reactions

In a breastfed baby, milk proteins consumed by the mother can cause a reaction in the baby after nursing. The breastfeeding mother must cut out all milk -- including cow, sheep and goat -- and soy products to remove the proteins from her breast milk. This can be challenging since many processed foods contain at least traces of soy or milk products. It can take 2 to 4 weeks to eliminate your baby's milk protein intolerance symptoms, although you may see an improvement in a few days, according to the Today's Dietitian website.

Timing of Milk Intolerance Symptoms

Some symptoms happen shortly after consuming milk protein, usually within 2 hours. This is often true of hives or rashes. Other symptoms take longer to appear -- anywhere from 48 hours to 1 week after drinking milk. Symptoms generally first start appearing during the first week your baby is exposed to the milk proteins. Many babies eventually outgrow the sensitivity to milk proteins. About half no longer have the intolerance at 1 year. By age 3, about 75 percent of kids outgrow the intolerance. At 6, about 90 percent are free of milk protein intolerance, according to the GI Kids website.

About the Author

Based in the Midwest, Shelley Frost has been writing parenting and education articles since 2007. Her experience comes from teaching, tutoring and managing educational after school programs. Frost worked in insurance and software testing before becoming a writer. She holds a Bachelor of Arts in elementary education with a reading endorsement.