Please bare in mind a dairy allergy and being lactose intollerence are two totally different problems. I have put two sets of asymptoms on this page check half way down for dairy allergy symptoms. The symptoms directly below are symptoms for people who suffer from lactose intollerance:
Lactose is made up of two small sugars, and made up is a large sugar molecule. The two sugars are glucose and galactose. The intestine would normally absorb the lactose by splitting it into the two, glucose and galactose. Lactose would normally be split by an enzyme called lactase.
When you are alleregic to dairy or lactose intollerant, this is because the enzyme that would normally split the lactose in to the two smaller sugars glucose and galactose, is absent (lactase defiency). A lactase defiency may be caused by any of the following threee reasons, congenital, secondary or developmental.
An actual allergic to milk is a response from you body overreacting to the milk. Your body assumes the milk is an alien and is going to harm you. So pumps the body with Hisatamine and over chemicals causing the following symptoms: