What 'Nil by Mouth' Means

When a doctor writes a nil by mouth order, or NPO, it means you must not consume any food or drink. This includes water, ice chips, coffee, and chewing gum. This restriction stays in place until your healthcare team explicitly cancels it. You will see this noted on your chart and often on a sign above your bed.

The primary reason for this rule is your safety during anesthesia. When you are sedated, your body's natural reflexes, like swallowing or coughing, are temporarily turned off. If your stomach contains food or liquid, you could accidentally vomit and inhale those contents into your lungs. This dangerous complication is called aspiration and can cause severe pneumonia or airway obstruction.

You might wonder why a sip of water or a single mint makes a difference. Your stomach constantly produces gastric juices, and even clear liquids stay in the stomach for a specific time. Anesthesiologists need your stomach to be completely empty to ensure the safest possible environment for your procedure. Breaking this rule often forces us to delay or cancel your scheduled surgery.

We know that fasting is physically and mentally difficult. If you are struggling, tell your nurse so we can track your comfort levels and monitor for signs of dehydration. We often provide fluids through an intravenous line to keep you hydrated without putting anything in your stomach. Once your procedure is finished and your medical team gives the green light, you can begin drinking and eating again.