Does Mounjaro slow stomach emptying?

Yes—Mounjaro (tirzepatide) does slow stomach emptying, an effect known as delayed gastric emptying or delayed gastric transit. This is a recognised action of GLP-1–based medicines and dual GIP/GLP-1 agonists like tirzepatide, and it helps reduce post-meal blood sugar rises and can contribute to feeling fuller for longer. UK guidance notes this delay can affect how quickly some oral medicines are absorbed, so certain tablets may need monitoring or timing adjustments while on tirzepatide. The effect tends to be most noticeable when starting treatment and may lessen over time in some people, but it remains clinically relevant for safety and when planning procedures like anaesthesia in the NHS.

• Mounjaro (tirzepatide) delays gastric (stomach) emptying.
• This slowing helps blunt post-meal blood sugar spikes and can increase fullness.
• UK guidance advises monitoring some oral medicines because absorption can be delayed.
• The effect may be stronger early in treatment and can diminish in some people over time.
• Anaesthesia teams consider this delay due to aspiration risk, per UK safety updates.

Sources

• NICE – Practical guide to using tirzepatide (prescribing, reviewing, stopping)
• MHRA Drug Safety Update – Aspiration risk with GLP-1/GIP-GLP-1 agonists during anaesthesia
• Endocrinology – Mechanisms of GLP-1 effects on gastric emptying
• Journal of Clinical Endocrinology & Metabolism – Review of incretin therapies and gastric motility
• EMA – Mounjaro (tirzepatide) product information (SmPC)