Yes, cow’s milk is a common allergen. Monitor your baby for any signs of an allergy and speak with your pediatrician if you suspect an allergy. Signs of a cow’s milk allergy include wheezing, trouble breathing, coughing, vomiting, diarrhea, itchy, watery or swollen eyes, etc. A child may have an intolerance to milk, which is different than an allergy, and may cause symptoms like loose stools, blood in stool, or irritability.