So how long should you be NPO before surgery? Every patient’s circumstances are different. However, in general, adults should have nothing to eat for six hours prior to surgery or procedure, and are allowed to drink clear liquids for up to two hours prior to scheduled procedure or surgery. Clear liquids are anything you can look through. For example, water, clear apple juice, even black coffee. Anything milky, thick and creamy or liquids containing pulp are not considered clear liquids and will fall into the six hour NPO window. Unfortunately not adhering to the NPO guidelines can result in your surgery or test to be canceled or delayed. If your instructions are not clear, or you have any questions regarding your NPO instructions, do not hesitate to contact your doctor’s office prior to your scheduled procedure or test.