The milk protein is destabilized and particles may appear floating in the milk. A better solution is to purchase only the amount of milk you can use within a week. The shelf life of milk is affected by several factors including how the product was handled before it reaches the consumer. When stored at 40 degrees Fahrenheit and not left unrefrigerated for extended periods, it should last approximately 7 days past the sell-by date on the container. Milk allergies are an abnormal response by the body to milk protein.
Lactose intolerance is the body's inability to digest lactose, the sugar in milk.
Allergies to milk are rare, while lactose intolerance is not. If milk allergy is suspected, consult a board-certified allergist for diagnosis. Those diagnosed with milk allergy should avoid consuming dairy foods, and should consult with a registered dietitian about how to get adequate calcium in the diet. Dairy food consumption can resume when and if the allergy is outgrown. Some who have low levels of lactase are unaware of it and never experience any symptoms.