Milk allergy should not be confused with lactose intolerance. Milk allergy is a food allergy, which is an overreaction of the immune system to a specific food protein. When the food protein is ingested, it 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.). Reactions to milk can be severe and life-threatening (read more about anaphylaxis).
Milk allergy is sometimes referred to as dairy allergy, but this term should be used with caution. Dairy is a category of products that contain cow’s milk. Since this is a product category – not a single ingredient (such as milk) – it is not listed in ingredient statements on processed foods. The Food Allergen Labeling and Consumer Protection Act requires that products containing milk list it as an ingredient, and so when teaching others about this allergy, using the term milk instead of dairy can help them better read ingredient labels. The term “dairy allergy” can also cause confusion with egg allergy since eggs are usually located near the dairy product case in the grocery store. Using the specific term – milk allergy – helps to eliminate this confusion.
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, individuals who are lactose intolerant 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.