Milk allergy should not be confused with lactose intolerance. A food allergy is an overreaction of the immune system to a specific food protein. When the food protein is ingested, in can trigger an allergic reaction that may include a range of symptoms from mild symptoms (rashes, hives, itching, swelling, etc.) to severe symptoms (trouble breathing, wheezing, loss of consciousness, etc.). A food allergy can be potentially fatal.
Unlike food allergies, food intolerances do not involve the immune system. People who are lactose intolerant are missing the enzyme lactase, which breaks down lactose, a sugar found in milk and dairy products. As a result, lactose-intolerant patients are unable to digest these foods, and may experience symptoms such as nausea, cramps, gas, bloating and diarrhea. While lactose intolerance can cause great discomfort, it is not life-threatening.