A study published in the journal Anaesthesia examined more than 47,000 patients in the United Kingdom. It identified about 1,350 people who had been using GLP‑1 medications for at least three months before their operation. The researchers found that these patients were eleven times more likely to regurgitate or aspirate while under general anaesthetic than patients not taking the drugs.

GLP‑1 drugs work by mimicking a natural hormone that slows gastric emptying and prolongs the feeling of fullness. Because digestion is delayed, the usual pre‑operative fasting of six hours may not be enough to empty the stomach.

The Australian and New Zealand College of Anaesthetists (ANZCA) therefore advises patients on GLP‑1 therapy to drink only clear fluids for the 24 hours before surgery and then observe a six‑hour fast. Anaesthetists also stress that patients must tell their medical team about any GLP‑1 or unapproved peptide use, since aspiration can be fatal when airway reflexes are suppressed by anaesthesia.