GLP-1 medicines and your gut

Why these medicines affect your gut

Glucagon-like peptide-1 (GLP-1) medicines work partly by slowing how quickly the stomach empties and by acting on appetite signals. That's part of how they help — and it's also why the gut feels them most.

Common gut effects include nausea, reflux, burping, constipation, feeling full very quickly, and sometimes loose stools. These are usually most noticeable when starting the medicine or moving up a dose, and often settle as your body adjusts. If they don't settle, that's a conversation for your prescriber — dose pacing can often be adjusted.

Gentle habits many people find helpful

These are general comfort habits, not treatment:

• Smaller meals, eaten slowly. A slower stomach copes better with less at a time.
• Stop when comfortably satisfied rather than full — fullness arrives late when emptying is slow.
• Go easy on rich, fatty or very large meals, which sit longest in the stomach.
• Stay upright for a while after eating if reflux bothers you.
• Sip fluids through the day, and for constipation, build fibre up gradually alongside fluids and gentle movement.
• Keep your nutrition quality up. With a smaller appetite, what you do eat matters more — regular meals with protein, fibre and variety. If eating starts to feel stressful or hard, tell your doctor.

Before a procedure — tell your care team

Because these medicines slow stomach emptying, they matter for sedation safety — food can remain in the stomach even after normal fasting times, which raises the risk of aspiration under anaesthesia. Always tell your care team you take a GLP-1 medicine before any procedure or operation.

This means a modified fast for your procedure. Follow the exact instructions in your bowel preparation sheet and confirmation letter — in particular, if you take a GLP-1 medicine you are asked to skip breakfast on the day before your procedure and follow the modified clear-fluid fasting they set out. Those instructions always come first, and we confirm them with you at your consultation. If your GLP-1 medicine is part of diabetes care, never stop it without specific instruction from your GP, endocrinologist or our team, because your blood-sugar management may need adjusting around the procedure.

When to talk to your doctor

See your doctor promptly if you have severe or persistent vomiting, can't keep fluids down, show signs of dehydration, or have severe or persistent tummy pain — these need assessment rather than self-management. Ongoing reflux, constipation or nausea that isn't settling is also worth raising with your prescriber rather than pushing through.

This page is general education to support — never replace — the advice of your prescriber and care team.