Nothing by mouth

Alcohol overdoses that result in vomiting or severe external bleeding also warrant NPO instructions for a period.

Pre-surgery NPO orders are typically between 6 and 12 hours prior to surgery, through recovery suite discharge, but may be longer if long acting medications or oral post-meds were administered.

[citation needed] The NPO periods for illness tend to be much longer, although exceptions are made for small scheduled amounts of water consumption if an IV drip is not in use.

When nothing by mouth or a liquid-only diet is indicated for an extended period, enteral feeding or total parenteral nutrition may be recommended.

However, it has been demonstrated in a large retrospective analysis in Torbay Hospital that unrestricted clear oral fluids right up until transfer to theatre could significantly reduce the incidence of postoperative nausea and vomiting without an increased risk in the adverse outcomes for which such conservative guidance exists.