GLP-1 Drugs Before Surgery: When to Stop and Why the Anaesthesiologist Cares

GLP-1 drugs became a standard perioperative concern after widespread adoption created a consistent pattern: patients presenting for elective surgery with delayed gastric emptying from their medication, despite following standard nil-by-mouth instructions.

This article awaits medical-reviewer signoff.

The mechanism of concern

GLP-1 receptor agonism slows gastric emptying — this is part of how the drug produces earlier satiety and weight loss. It means that after a meal, food remains in the stomach longer than in a patient without GLP-1 agonism.

Standard pre-procedural fasting (nothing by mouth for 8 hours for solid food, 2 hours for clear liquids) is calibrated to normal gastric emptying. A GLP-1-treated patient may have residual gastric contents after 8 hours that a non-treated patient would not.

During anaesthesia induction and airway management, the upper oesophageal sphincter relaxes and the gag reflex is suppressed. Residual gastric contents can passively reflux into the airway, causing pulmonary aspiration — a serious, potentially fatal complication.

The GLP-1 effect on gastric emptying is dose-dependent and varies by individual. It may be less pronounced in patients who have been on stable GLP-1 therapy for an extended period (some adaptation occurs), but the variability means the anaesthesiologist cannot reliably assume normal gastric emptying without additional assessment.

What the guidance says

2023 ASA consensus

The American Society of Anesthesiologists (ASA) issued consensus guidance in June 2023:

• Weekly GLP-1s (Ozempic, Wegovy, Mounjaro, Zepbound): Hold for 1 week before elective procedures
• Daily GLP-1s (Saxenda/Victoza, Rybelsus): Hold on the day of procedure

This applied regardless of the indication (T2D or obesity) and regardless of dose.

2024 update — risk stratification added

A 2024 multi-society consensus document in Clinical Gastroenterology and Hepatology added nuance:

• Patients with no GI symptoms (no nausea, vomiting, or abdominal fullness on their current GLP-1 dose) may be lower risk; rigid 1-week holds may not be necessary in all such cases
• Patients with active GI symptoms are higher risk and warrant point-of-care gastric ultrasound or more cautious management
• Procedure type matters: upper GI procedures and endoscopic procedures carry higher risk than peripheral procedures

2025 ASA updated guidance

The ASA refined the guidance to make GI symptom assessment the primary clinical decision factor at pre-operative evaluation — not just medication list review.

What this means for patients

The protocol depends on your surgical team, procedure type, and GI symptom status. The consistent message across all guidance versions:

1. Tell your anaesthesiologist you are on a GLP-1 drug — before every procedure, including minor ones and dental procedures requiring sedation. Many patients do not realise their medication is relevant; many surgical teams do not ask.

2. Do not manage the hold independently. For T2D patients on Ozempic or Mounjaro, stopping a GLP-1 has glycaemic implications. The perioperative hold requires coordinating between your prescriber (for glucose management during the hold) and your surgical team. Patients who stop independently without a glucose management plan can experience significant glycaemic deterioration.

3. Ask about point-of-care gastric ultrasound at your pre-operative assessment. Some centres now use bedside ultrasound to assess gastric volume in GLP-1 patients as a direct measure rather than relying on symptom assessment alone.

T2D patients: additional considerations

For T2D patients whose GLP-1 is the primary glycaemic agent:

• Stopping 1 week pre-operatively removes glycaemic control for that period
• Alternative agents (insulin, metformin) may need to cover the peri-operative gap
• Post-operative glucose management during recovery is an active clinical consideration
• The prescriber and surgical/anaesthesia team should communicate before the procedure

Resumption post-operatively is typically when oral intake is re-established and the patient is clinically stable — usually 1–2 days post-procedure for uncomplicated surgeries, longer for major procedures.

Emergency surgery

Emergency procedures cannot accommodate a GLP-1 hold. Anaesthesia teams use rapid sequence induction and aspiration-precaution techniques when there is known or possible delayed gastric emptying.

Action: carry medication information. Medical alert bracelet, medication card, or a note in your phone that includes your GLP-1 medication, dose, and prescriber contact. If you are incapacitated and cannot communicate, this information is critical for safe anaesthesia management.

Editorial note: This article awaits medical-reviewer signoff. Perioperative GLP-1 management is a clinical decision — procedure type, GI symptom status, T2D management needs, and anaesthesiologist judgment all factor in. Do not discontinue GLP-1 therapy before a procedure without coordinating with your prescriber and surgical team.