A cow’s milk protein allergy results from the baby’s immune system reacting to the protein in cow’s milk. Milk protein allergy is by far the most common food allergy in infancy. The symptoms can appear anywhere from a few minutes to a few hours or days after the baby is exposed to the protein. Generally, babies become less sensitive as they grow older, and this type of allergy may disappear by the time they are one or two years old. The most common symptoms are fussiness and vomiting and/or diarrhea, although you also might see blood or mucus in the stools, skin rash (eczema), a stuffy nose, and hives or wheezing. If you suspect that your baby is allergic to the protein in cow’s milk, discuss the possibility with your baby’s doctor. As you are formula feeding, the doctor might recommend a special, hypoallergenic† formula with extensively hydrolyzed protein, like Similac® Alimentum®.
Partially hydrolyzed formulas are not hypoallergenic† and are not recommended for babies with a diagnosed cow’s milk protein allergy. Neither are soy-based formulas, since babies who are allergic to cow’s milk protein may also react to soy protein.
Please note that this information is not meant to replace the advice of your baby’s health care professional who we recommend you contact if you are concerned, or before making changes to your baby’s diet.
† “Hypoallergenic” does not mean “non-allergenic".