Q&A: Baby Allergic To Cow's Milk?
As long as your baby is happy, gaining weight, and her poops seem pretty normal, there's no need to worry.
Only a small percentage of babies are sensitive to a protein found in cow's milk. But if baby has suspicious allergy-like symptoms (excessive gas, spitting up, fussing, a rash, irritability, intestinal upset or green stools with mucus or blood), you can try eliminating cow’s milk ingredients from your diet for a couple of weeks to see if you see improvement. If you don't see a change in about two weeks (it can take that long for the proteins to leave your system), baby probably isn't sensitive. If you do notice improvement, congrats — you've probably found the culprit.
Note that many babies outgrow food sensitivities as they get older. If you think baby is sensitive to cow's milk or another ingredient in your diet, work with your pediatrician on a game plan for reintroducing these foods as baby gets older.