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GLP-1 medicines, surgery and anaesthesia

Tell the team doing your procedure about any GLP-1 medicine, including a private prescription for weight management. Contact them before the appointment so they can give you a personal plan for medicines and fasting.

Published by Penzilla Editorial Team. Sources checked 23 October 2026. General information for a conversation with your healthcare team.

Why the anaesthetist needs to know

GLP-1 medicines and the dual GIP/GLP-1 medicine tirzepatide slow the emptying of the stomach. The MHRA warns about a possible risk of stomach contents entering the lungs during general anaesthesia or deep sedation. Food may remain in the stomach despite following fasting instructions.

The warning covers procedures with deep sedation as well as surgery under a general anaesthetic. Ask the clinic what type of anaesthesia or sedation is planned if you are unsure. A private prescription may be absent from your hospital medicine record, so mention the medicine directly even when the referral lists your other treatment.

A medicine record to bring to pre-assessment

You can copy these prompts into a note or take the labelled packaging. Give the record to the pre-assessment team and confirm the details again with the team treating you.

Medicine name and form

Record the brand, active ingredient and whether you use a pen or tablet.

Your current prescription

Record the prescribed strength, frequency, date of the last dose and any recent change.

Reason for treatment

Say whether you take the medicine for diabetes, weight management or another reason discussed with your prescriber.

How you have been feeling

Describe nausea, vomiting, bloating, stomach pain or problems eating and drinking.

Other medicines and contact details

Include other prescriptions and the name of the clinician or pharmacy managing this treatment.

Questions which need an answer from your team

1. What should I do with this medicine before my procedure, and who will confirm the instructions?
2. What are my exact food and fluid instructions, including the time to start fasting?
3. Who should I call if I vomit, become unwell or receive conflicting advice?
4. If I have diabetes, who will plan glucose monitoring and any changes to other medicines?
5. What is the plan for taking treatment again after the procedure, especially if eating and drinking remain difficult?

Do not use a generic stop date

The MHRA explains the evidence did not establish a single pause interval or fasting rule suitable for everyone. The UK multidisciplinary consensus and its patient information support an individual plan. This page gives no instruction to stop, continue or restart your own medicine. Your anaesthetist and prescribing team need to account for your procedure and medical history.

If two letters give different instructions, contact the pre-assessment service and ask them to reconcile the advice with your prescriber. Keep the agreed instructions with the appointment letter. Do not substitute a social media timetable for the plan from your team.

An urgent procedure is different

Tell the team immediately what you take and when you last took a dose. Do not delay seeking urgent care while trying to reach the prescribing pharmacy. The team can assess the procedure and anaesthetic risks using the information available.

For the medicine's other warnings, see tirzepatide side effects or semaglutide side effects. Those pages do not replace your procedure instructions.

Sources

1. MHRA, Potential risk of pulmonary aspiration during general anaesthesia or deep sedation, January 2025
2. Centre for Perioperative Care, Patient information accompanying the UK multidisciplinary consensus, January 2025