NPO (nothing by mouth)
NPO means nothing by mouth: no food, drink or medicine taken orally. It is from the Latin nil per os; British hospitals say “nil by mouth”.
How to read it
The American Heritage Dictionary gives NPO as nil per os, “nothing by mouth”; a 2010 paper in the Indian Journal of Anaesthesia gives the Latin as nulla per os. The per os is the same as in PO, “by mouth”. In the UK the order is written in English. A Norfolk and Norwich University Hospitals patient leaflet explains “nil by mouth” as no food, drink or medications by mouth, and includes sweets, ice cubes and ice lollies.
Also searched as: nil per os, n.p.o., npo meaning, npo medical abbreviation.
These pages explain what medical abbreviations and symbols stand for. They are not medical advice and give no doses: a pharmacist or prescriber can explain what any label means for you.
Where NPO orders appear
The best-known use is before surgery. Kajal Dalal and Dhanwanti Rajwade wrote in 2010 that NPO after midnight, for solids and clear fluids alike, was common practice, while recent guidelines had moved to a more relaxed policy on clear fluids a few hours before surgery. NPO is also ordered outside surgery: the Norfolk and Norwich leaflet is written for patients whose speech and language therapist has advised nil by mouth because of swallowing difficulties. ISMP’s guidelines for electronic prescribing list NPO status among the details a prescribing system is to show.
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Sources
- NPO (American Heritage Dictionary entry), The American Heritage Dictionary of the English Language, Fifth Edition, HarperCollins Publishers, NPO, abbr.
- “Nil per oral after midnight”: Is it necessary for clear fluids?, Kajal S. Dalal and Dhanwanti Rajwade, Indian Journal of Anaesthesia 2010;54(5):445–447, Indian Society of Anaesthesiologists, Introduction; Discussion
- Nil by Mouth (patient information leaflet), Norfolk and Norwich University Hospitals NHS Foundation Trust, Speech and Language Therapy Department (approved 2024), Norfolk and Norwich University Hospitals NHS Foundation Trust, What does it mean to be Nil by Mouth?
- Guidelines for Safe Electronic Communication of Medication Information (2019), 2019 edition, Institute for Safe Medication Practices, Prescribing, contextual information
Last reviewed September 30, 2026 by Rory Hansen. How we research