A dairy allergy is an immune response to proteins found in milk and dairy products, such as casein and whey. When someone with this allergy consumes dairy, their body mistakenly identifies these proteins as harmful, leading to symptoms like hives, stomach pain, or difficulty breathing. This condition is different from lactose intolerance, which is a digestive issue rather than an immune response. Dairy allergies are more common in children, but some may outgrow it. Treatment typically involves avoiding all dairy products and reading labels carefully to prevent exposure to hidden dairy ingredients.