What does NPO stand for?

• A. Nitrate Potassium Oxide
• B. Nothing by mouth
• C. Nebulized Potassium Output
• D. Non-Pharmacologic Order

Answer: (B)

Nothing by mouth is a medical instruction used to keep a patient from taking anything by mouth. This is important before procedures or anesthesia because it lowers the risk of food and liquids entering the airway (aspiration) if the patient is unconscious or sedated. In practice, it means no solids or liquids come from the mouth, though sometimes essential medications may be given by other routes if the clinician approves. The phrase is shorthand for nil per os, with per os meaning by mouth.

The other phrases aren’t recognized medical instructions in this context. They don’t correspond to standard orders used for patient care, so they don’t convey the same, clear restriction on oral intake as Nothing by mouth does.