If your baby seems particularly fussy or irritable after a formula feeding, she might be allergic to the protein in cow's milk. Though formula is specially created with nutrients designed for growing infants, its basis is usually cow's milk -- and the dairy you consume reaches your baby through your breast milk. Cow milk allergies happen when the immune system mistakes the milk protein as something the body should fight off, says KidsHealth. The good news is that an allergy to cow's milk is easily treatable -- either with a specialized formula or a change in your own diet -- and most kids outgrow it by age 2 or 3, according to Ask Dr. Sears.
Pay close attention to your baby's symptoms, which will usually appear within the first few months of life, recommends KidsHealth. Some babies experience slower onset symptoms -- seven to 10 days after consuming the cow's milk protein -- which include loose stools, vomiting, gagging, refusing food, irritability or skin rashes such as eczema. Less commonly, infants have rapid onset symptoms, which come on right after a feeding: irritability, vomiting, wheezing, swelling, hives, itchy bumps on skin or bloody diarrhea. Also, if your baby seems to have repeated colds and ear infections, take note, says Ask Dr. Sears. This could be the result of fluid building up in the respiratory passages, sinuses and Eustachian tubes of the ears, caused by an allergic reaction. Infants with this symptom will often exhibit subtle changes in behavior, such as irritability and night waking.
Call your baby's pediatrician if you suspect she has a cow's milk allergy, and make an initial appointment, KidsHealth suggests. Your doctor will ask about your family's history of allergies or food intolerance and then do a physical exam. Unfortunately, your child will have to undergo several tests to make an allergy diagnosis and have other health issues ruled out. Commonly, the doctor will give a blood and stool test, as well as an allergy skin test, where a tiny amount of milk protein is inserted beneath the surface of your child's skin with a needle. Your doctor will look for a raised spot to appear on her skin -- called a "wheal" -- and if it does, she might have a milk allergy. The pediatrician might also recommend an "oral challenge" test if she feels it's safe, which involves your baby consuming milk during the checkup -- then waiting in the office for a few hours to be watched for a reaction. In some cases, doctors will repeat this type of test, so that a diagnosis can be confirmed.
Avoid consuming dairy if you're breast-feeding, and switch to a soy-protein-based formula if you're formula-feeding, once your pediatrician has confirmed a cow's milk allergy. If you're breast-feeding, you might want to talk with your own doctor about other ways to get calcium and other nutrients into your diet because you won't be able to consume dairy products. If you've been formula-feeding, try the soy-protein-based formula first -- if it seems your baby isn't tolerating that well, your doctor might have you try a hypoallergenic formula. In these, proteins are broken down into particles, making it less likely that it will trigger an allergic reaction.
Talk with your child's pediatrician before trying alternatives to breast milk and commercial formula. For example, notes Ask Dr. Sears, in theory, goat's milk is less allergenic and more easily digestible than cow's milk -- but it's not a viable substitute for infant formula because it can cause intestinal irritation and anemia. Similarly, rice milk and almond milk -- while a healthy choice for toddlers, children and adults -- are not safe or recommended for infants.
If you're breast-feeding and need to restrict dairy products from your diet because you've discovered your infant has a cow's milk allergy, you may want to consider consulting a nutritionist. She can suggest healthy foods to replace the vitamins and minerals you'd normally be getting from dairy.
If your baby's pediatrician recommends a hypoallergenic formula, be sure to read the label carefully, says KidsHealth. There are "partially hydrolyzed" formulas on the market that can still cause a significant allergic reaction.