GLP-1s slow gastric emptying, and a standard pre-operative fast may not empty the stomach

Published: 2026-08-01 · Last reviewed: 2026-08-01 · Methodology v4.1 · News
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Anaesthesia guidance exists because case reports described residual gastric contents after adequate fasting. It applies to compounded products too.

Pre-operative fasting rules assume a normal rate of gastric emptying. A GLP-1 deliberately slows it, which is part of how it works — and which breaks the assumption the rules are built on.

The specific failure mode with compounded products: a patient on a branded pen usually names it. A patient on a telehealth compounded preparation frequently says "a weight-loss shot" or nothing at all, because it does not feel like a prescription drug in the same way. It is the same molecule with the same effect.

One sentence covers it: "I take [drug] at [dose], [weekly or daily], last dose [date]." It applies to any procedure involving sedation, including endoscopy, colonoscopy and dental sedation. Full detail: GLP-1s and surgery.

Filed by the Peptides Editorial research desk. Corrections: the corrections log.