Nearly all infants are fussy at times. But how do you know when your baby's crying means something wrong? Some babies are excessively fussy because they are being fed formula containing cow's milk, and are allergic to a protein contained in the milk.
People of any age can be allergic to dairy, but it is more common among infants. Babies have a 2% to 3% chance of being allergic to milk, although most will outgrow it by the time they are school-aged. This allergy occurs when the immune system mistakenly sees the milk protein as a harmful substance.
Symptoms of the allergy usually appear in an infant's first few months of life. Some babies experience an immediate reaction when fed cow's milk, though others experience delayed symptoms, up to a week after ingesting milk. The reaction can cause an infant to be irritable or fussy, along with an upset stomach, vomiting, gagging, refusing food, loose stools, and skin rashes such as hives or eczema. Rarely, a life threatening reaction known as anaphylaxis can occur, although it is more common with other food allergies.
If you think that your child has a dairy allergy, talk to your child's pediatrician about allergy testing and alternatives to milk-based baby formula and dairy products. Most children who have a dairy allergic react to cow's milk, goat's milk, and sheep's milk, and may also react to soy milk, making careful choice of baby formula important. There are hypoallergenic formulas available that are safe for infants with a dairy allergy.