Weight loss injections before surgery: do you have to stop?

For most people, stopping isn't required, but telling your doctors is.¹²³ This covers weight loss injections that contain semaglutide or tirzepatide. Semaglutide is a GLP-1 medicine, and tirzepatide acts on GLP-1 and a second hormone, GIP.⁴³⁵ Under guidance published in 2024 by five medical societies, people at low risk can keep taking their medicine before planned surgery.¹ People who are still increasing their dose, have stomach symptoms, are on a high dose, or have another condition that slows the stomach may need extra precautions or a delay.¹⁵ Your surgeon and your anaesthetist make the final call together with you.¹

What's the actual problem?

These medicines make you feel full, and they slow down how quickly your stomach empties.¹³ So even after hours of fasting, there can still be food in your stomach.³ Under general anaesthesia or deep sedation, that can come back up and get into your lungs, which can cause a serious pneumonia.¹³

What the guidance says now

In October 2024, five societies including the American Society of Anesthesiologists published joint guidance that lets most people keep taking their medicine.¹ In short:

• Low-risk patients can keep taking the drug.¹
• The risk is higher in the first weeks, while the dose is still being stepped up, so the team should check this early enough to change the plan if needed.¹⁵
• Nausea, vomiting, stomach pain or constipation are warning signs too. If they're severe, planned surgery may have to wait until the doctor who prescribed the medicine has adjusted your diet or treatment.¹⁵
• People at higher risk, such as those on higher doses, may be asked to stick to liquids for at least 24 hours before the procedure.¹
• If there's concern on the day that the stomach isn't empty, the team may check it with a bedside ultrasound right before surgery, where that is available.¹

The guidance also points out that stopping has its own risks, like blood sugar going up in people with diabetes.¹

Newer guidance agrees. In 2025, a group of UK medical bodies said patients should keep taking these medicines before and after surgery,² and the UK medicines regulator's advice for patients is not to stop without first talking to their doctor.³ A 2026 review of five guidelines found that four of them now recommend carrying on, with changes to fasting.⁶ Some of that guidance asks more people to prepare, though: a 2025 US consensus advises no solid food, only clear liquids, for the 24 hours before anaesthesia for anyone on these medicines who has no significant stomach symptoms.⁵

So why are some people still told to stop a week before?

Because that was the American Society of Anesthesiologists' advice in 2023: pause a weekly shot for a week before surgery.¹⁶ The 2024 guidance still uses that week when the team decides stopping is needed, but it no longer asks most people to stop.¹ UK guidance adds that even a week off may not be enough to empty the stomach.² Teams also work to their own protocols, and the guidelines still differ on the details.³⁶ If you hear two different answers, that's why. What counts is the written plan your own surgeon and anaesthetist give you.

Loose skin, a hollower face and when to have surgery

Losing weight fast can leave loose skin and a hollower face.⁷⁸ A 2026 review says that look more likely comes from rapid or large weight loss than from the medicine itself.⁹ If you're thinking about a tummy tuck, the American Society of Plastic Surgeons advises being at a stable weight first, because big changes in weight can greatly reduce the result.¹⁰¹¹ Weight stability matters for other body contouring too, such as an arm lift.⁹ Ask your surgeon how long they want your weight to be stable first.

Before your consultation

Tell both your surgeon and your anaesthetist that you're on it, what dose, and when you last took it.³¹ If you've had nausea or vomiting, mention it.¹ Feeling fine doesn't prove your stomach is empty, so tell them even if you have no symptoms.²⁶ Don't stop on your own,³ and don't decide by yourself when to restart after surgery.⁵

If you've been through this, or it's coming up for you, you can ask your own question on Glojour. Glojour's treatment library covers the operations themselves, tummy tuck and liposuction included.

This article is general information. Decisions about your own treatment belong with your doctor.