Milk allergies are usually related to cow’s milk, though usually any childhood milk allergies are gone by age three. However, sometimes these can last a lifetime and begin in early childhood. In fact, the allergic reaction to milk usually happens within minutes or might not occur for up to four hours, lasting up to a full day. More severe reactions can result in a shock reaction which requires emergency care. Regardless of the reaction time, a milk allergy does not necessarily have to be as a result of drinking milk as it can come from any type of milk product or food. In some cases, the reaction does not occur until there has been a substantial build up over time of the milk proteins. It can happen through varied forms, including drinking and eating, but also skin contact with a milk product, something that has been in contact with a milk product or someone who has had a milk product and still has remnants on their skin or lips.