If lactose intolerant and drink milk when will the bloating go away ?

Up to 4 hours: Undigested lactose begins to form gas when it utilized by gut bacteria in the colon. Usually 1 to 2 hours after it is ingested. Gas produced is usually hydrogen. Bloating will stop when there is no more lactose available to the intestinal bacteria.

Will not go away: If you are lactose intolerant your symptoms will improve on lactose free diet. Drink lactose free milk. See your doctor to make sure that you do not have any other cause of your symptoms.