Hi, Thanks for writing in. The magnesium citrate is given to patients to help empty the bowel before a scheduled surgery. Magnesium citrate is a liquid preparation used to cleanse the bowel in preparation for abdominal surgery. It is a very salty drink that after ingestion will cause him to have stools until his bowels are emptied. In some people the bowel movements can be delayed. Please do not worry about it and there is no urgent need to call the hospital for this reason. He can be allowed clear liquids after the magnesium citrate up until midnight, at which time he cannot have nothing to eat, drink, smoke, or chew until after the surgery.