General anesthesia is often associated with postoperative nausea and vomiting (PONV), which can raise recovery room, hospital stay, and overall health care costs. The reduced frequency of PONV still persists even after introducing shorter surgical procedures, shorter-acting anesthesias, and newer anti-emetic medicines. Still, many anti-emetic treatments are expensive and do not completely eliminate PONV with some adverse effects. Preoperative fasting can reduce stomach volume and acidity, serving as a precaution against regurgitation and aspiration of stomach contents. The current standards in Europe advocate the consumption of clear oral fluids up to two hours before the onset of general anesthetic induction. 

A recent study reviewed the effects of free oral consumption of clear fluids before the anesthesia on nausea and vomiting beyond surgery.

It explored the databases [PubMed – Medline - Google scholar- science direct] for the relevant articles published in English and found a lower incidence of postoperative nausea and vomiting when patients drank freely clear fluids before the scheduled induction of day case anesthesia.

Salama AM, Farid DM, Mohammed HH, Wahdan RA-A. Preoperative Unrestricted Clear Fluid and Association with Postoperative Nausea And Vomiting: Review Article. The Egyptian Journal of Hospital Medicine. 2022;86(1):566-569. DOI: 10.21608/EJHM.2022.215110