It generally takes 4 to 5 hours for the stomach to empty after a full meal and a bit less after a snack or liquid, though it varies depending on how much and what kind of food you ate. If you can, it’s easiest to take empty stomach medications in the morning, after you’ve fasted overnight. After taking the drug, wait at least 30 minute before ingesting anything other than plain water, to give the body time to absorb the medication.