Taking a GLP-1 Medication Before Joint Replacement? What the Anesthesia Guidance Says
GLP-1 drugs slow the stomach, and that matters when you are put under anesthesia. Current guidance says most patients can keep taking them, but the details depend on your dose, symptoms and stage of treatment.
GLP-1 receptor agonists, the family of drugs that includes semaglutide and tirzepatide and is sold under names such as Ozempic, Wegovy and Mounjaro, are now common among people heading for a hip or knee replacement. Some take them for diabetes. Others take them for weight, sometimes because a surgeon has said that losing weight would make surgery safer or more effective.
That raises a practical question that anesthesia teams have spent the last few years working through: is it safe to be put under anesthesia while on one of these drugs, and should you stop before surgery? This guide explains the current guidance and the questions to raise. It is background only. Never stop or change a prescribed medicine without talking to the clinician who prescribed it and your surgical team.
Why anesthesia teams care about these drugs
GLP-1 drugs slow the rate at which the stomach empties. That is part of how they reduce appetite. But it also means food can still be sitting in the stomach hours later than expected, even after a patient has followed normal fasting rules.
According to the American Society of Anesthesiologists' announcement of multi-society guidance (2024), leftover stomach contents during general anesthesia or deep sedation raise the risk of regurgitation and aspiration, where stomach contents get into the airway and lungs. Aspiration can cause pneumonia that may be fatal. That is the specific risk the guidance is trying to manage.
What the 2024 guidance says
The guidance was issued jointly by the American Society of Anesthesiologists, the American Gastroenterological Association, the American Society for Metabolic and Bariatric Surgery, the International Society of Perioperative Care of Patients with Obesity and the Society of American Gastrointestinal and Endoscopic Surgeons. As summarised by the ASA, the key points are:
Most patients can continue the drug
Stopping the medication is not automatically the default. The guidance says most patients can continue their GLP-1 before elective surgery, and that teams should weigh the risk of delayed stomach emptying against the risks of stopping, such as higher blood sugar in people with diabetes.
Some patients are higher risk
The guidance identifies groups more likely to have delayed stomach emptying:
- People in the dose-escalation phase. Early in treatment, while doses are being increased, side effects are more likely. The ASA says this phase typically lasts four to eight weeks and that elective surgery should be put off until it has passed and stomach side effects have settled.
- People with current stomach symptoms such as nausea, vomiting, abdominal pain or constipation. The guidance says elective surgery should wait until these resolve.
- People on higher doses, which are associated with more side effects.
- People with other conditions that slow stomach emptying, such as Parkinson's disease.
A liquid diet for those at highest risk
For patients at highest risk of significant stomach side effects, the guidance recommends a liquid-only diet for 24 hours before surgery.
Other tools the team may use
The anesthesia team may adjust the anesthesia plan, and point-of-care ultrasound can be used just before the procedure to check whether the stomach still has contents.
| Your situation | What the 2024 guidance points toward |
|---|---|
| Stable dose, no stomach symptoms | Usually continue the medication; the team assesses your individual risk. |
| Recently started or still increasing the dose | Elective surgery generally deferred until the escalation phase is over and side effects have settled. |
| Nausea, vomiting, abdominal pain or constipation now | Elective surgery generally waits until symptoms resolve. |
| Higher dose or other higher-risk factors | A 24-hour liquid diet before surgery may be advised, and the anesthesia plan adjusted. |
These are summaries of a general guideline, not instructions. The anesthesia team at your hospital may have its own protocol, and your circumstances may call for a different approach.
Why this matters for joint replacement in particular
Hip and knee replacements are elective operations, which is exactly the setting this guidance addresses. They are often done under spinal or regional anesthesia rather than general anesthesia; the AAOS guide to total hip replacement (OrthoInfo, 2026) lists general anesthesia and spinal, epidural or regional nerve block as options. Sedation may be given alongside a spinal, though, and the ASA guidance covers deep sedation as well as general anesthesia. Do not assume a spinal makes your GLP-1 irrelevant. Let the anesthesia team decide.
There is also a timing issue specific to joint replacement. Many patients start a GLP-1 because they want to lose weight before surgery. OrthoInfo's hip guide includes weight loss, if recommended, as part of preparing for surgery. If you start or increase a GLP-1 with that aim, build in the escalation period: a surgery date that lands in the middle of dose increases may need to move.
Plan the calendar backward: if a GLP-1 is part of your preparation, talk to your prescriber and surgeon about when your dose will be stable, then choose the surgery date. Moving an operation late can be costly and disruptive, especially when travel is involved.
What to tell your team, and when
The single most important step is making sure everyone involved knows you take a GLP-1. That includes:
- Your orthopedic surgeon, at the first consultation.
- The anesthesia team, at the pre-operative assessment.
- The prescriber of the GLP-1, so they can plan around the surgery date.
- Your diabetes care team, if you have diabetes, since any change to the drug affects blood sugar.
Bring specifics, because they change the advice:
- The exact drug name and dose.
- Whether it is taken daily or weekly, and which day you take it.
- When you started and when your dose last went up.
- Any current nausea, vomiting, reflux, bloating, abdominal pain or constipation.
- Why you take it: diabetes, weight, or both.
- Any other medicines or supplements, including compounded versions of these drugs.
Questions to ask the anesthesia team
- Should I keep taking my GLP-1 before surgery, and if not, exactly when should I take my last dose?
- Do you want me on a liquid diet the day before? From what time?
- Will you check my stomach with ultrasound before the procedure?
- Will I have spinal or general anesthesia, and how much sedation?
- When can I restart the medication after surgery?
- If I have diabetes, how will my blood sugar be managed if the drug is held?
Common misunderstandings
"I fasted, so my stomach is empty"
Standard fasting rules assume your stomach empties at a normal pace. The whole point of the guidance is that GLP-1 drugs can slow that down, so the usual hours without food may not be enough for everyone. That is why some patients are asked to switch to liquids for a full day beforehand.
"I should stop the drug a few weeks early just to be safe"
Stopping on your own is not automatically safer. The guidance points out that stopping has its own risks, such as higher blood sugar for people with diabetes, and many patients can continue. Any change should be planned with your prescriber and surgical team.
"It is only a weight-loss shot, so it does not count as a medication"
It counts. Whether it was prescribed for diabetes or weight, bought through a telehealth service or compounded, the anesthesia team needs to know. Leaving it off a medication list is one of the easiest ways for this risk to be missed.
"My surgeon already knows, so the anesthesia team does too"
Do not assume information has been passed along. Say it again at the pre-operative assessment and on the morning of surgery.
If you are travelling for surgery
Patients having a joint replacement abroad usually meet the anesthesia team only a day or two before the operation, which leaves little room to adjust. Raise your GLP-1 use in writing when you first send your medical history, and ask the hospital to confirm its protocol before you book flights. Pack enough medication for the trip with written instructions on when to take or hold it. If your weekly dose day falls during travel, ask your prescriber how to handle it.
Some patients also take these drugs from sources outside their usual pharmacy. Tell the team exactly what you are taking and where it came from; that is part of an honest medical history, and it helps them judge your risk.
After surgery
Ask when to restart. Recovery after joint replacement depends on eating well; the AAOS hip guide notes that appetite may be reduced for several weeks and recommends a balanced diet and plenty of fluids. If you are also on a GLP-1 that suppresses appetite, mention it to your team, especially if nausea or poor eating is getting in the way of rehabilitation.
The bottom line
Being on a GLP-1 does not usually rule out a joint replacement, and current guidance does not tell everyone to stop. What matters is your dose, whether you are still escalating, whether you have stomach symptoms, and the anesthesia plan. Tell every member of your team early, bring the details, and let them set your instructions.
Common questions
Do I have to stop Ozempic before knee replacement surgery?
Not necessarily. The 2024 multi-society guidance announced by the ASA says most patients can continue GLP-1 medications before elective surgery, with exceptions for higher-risk patients. Your anesthesia team decides for you, so tell them early and follow their instructions.
Why is a GLP-1 a concern if I am having a spinal instead of general anesthesia?
Spinal anesthesia is often combined with sedation, and the guidance covers deep sedation as well as general anesthesia. Slowed stomach emptying can raise the risk of aspiration in both situations. The team will judge how relevant it is for your plan.
I just started a GLP-1 to lose weight for surgery. Does that affect my date?
It may. The guidance says the dose-escalation phase typically lasts four to eight weeks and recommends deferring elective surgery until it has passed and stomach side effects have settled. Coordinate the timing with your prescriber and surgeon.
What is the 24-hour liquid diet?
For patients at highest risk of stomach side effects, the guidance recommends consuming only liquids for the 24 hours before surgery. Your team will tell you whether it applies to you and which liquids are allowed.
When can I restart my GLP-1 after joint replacement?
Ask your surgical and anesthesia teams before surgery so you have a plan. Restart timing depends on how you are eating and recovering, and on why you take the drug.
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