Nil per os

Nil per os (alternatively nihil/non/nulla per os) (NPO) is a medical instruction meaning to withhold oral food and fluids from a patient for various reasons. It is a Latin phrase which translates as "nothing through the mouth". In the United Kingdom it is translated as nil by mouth (NBM).

Typical reasons for NPO instructions are the prevention of aspiration pneumonia, e.g. in those who will undergo general anesthetic, or those with weak swallowing musculature, or in case of gastrointestinal bleeding, gastrointestinal blockage, or acute pancreatitis. Alcohol overdoses that result in vomiting also warrant NPO instructions for a period of time.

When patients are placed on NPO orders prior to surgical general anesthesia, physicians would usually add the exception that patients are allowed a very small drink of water to take with their usual medication. This is the only exception to a patient's pre-surgery NPO status. Otherwise, if a patient accidentally ingested some food or water, the surgery would usually be canceled or postponed for at least 8 hours.

See also

• List of Latin phrases
• Medical prescription
• Per os
• Preoperative fasting