GLP-1s and anesthesia: What to know before surgery

GLP-1 agonists (GLP-1s) have helped thousands of people to manage diabetes, lower blood pressure, lose weight, reduce their risk of stroke and heart attack and improve their overall physical health.

But if you’re having a medical procedure that involves anesthesia, these drugs can also increase your risk of a complication called aspiration, or breathing food particles into your lungs.

The good news is that you don’t have to stop taking GLP-1s just to have surgery. Here’s what to know about GLP-1s and anesthesia, starting with four simple steps you can take to reduce your risk.

Step 1: Make sure that your care team knows you’re taking a GLP-1

This step is extremely important. If you’re taking a compounded version from a specialty pharmacy, it might not show up automatically on your medication list. So, don't just assume your care team will know. Be sure to mention it.

These medications include, but are not limited to:

• Dulaglutide (Trulicity)
• Exenatide (Bydureon and Byetta)
• Liraglutide (Saxenda and Victoza)
• Semaglutide (Ozempic, Rybelsus and Wegovy)
• Tirzepatide (Mounjaro and Zepbound)

Step 2: Specify which type of GLP-1 you’re taking, how much and how often

GLP-1 drugs come in two different forms: oral (pill) and injectable (syringe).

The pills have a fairly short half-life, which means they don’t stay active in your body for very long. That’s why they are usually taken daily. Even so, it may be four or five days until your body has completely cleared them from your system.

Injectables, on the other hand, tend to last a long time. So, those can take four or five weeks to be completely eliminated.

Step 3: Follow your care team’s instructions carefully

When recommendations first started coming out about pausing GLP-1s before undergoing anesthesia, it was thought that stopping the medication just one day before a procedure would be sufficient for anyone taking the pill form, and one week would be sufficient for anyone receiving the injectable form.

That thinking has since evolved, as evidence shows even a one-week hold is sometimes insufficient for the drug’s effects to wear off.

Now, anesthesiologists here at UT MD Anderson typically make dietary recommendations for patients preparing to undergo surgery, based on how long ago you took your last dose of GLP-1.

• If your last dose was more than 30 days ago, you can follow a standard diet the day before your procedure, but you shouldn’t eat or drink anything after midnight.
• If your last dose was 30 days ago or less, then you must follow a clear liquid diet beginning at 8 a.m. the day before your procedure and not eat or drink anything starting two hours before your arrival time.

We don’t recommend stopping the GLP-1s themselves anymore. It’s not really reasonable to ask people to hold off on taking those medications for that long.

Step 4: Be honest about how well you’ve followed the instructions

If there’s still a little food left in your stomach before a procedure involving anesthesia, that doesn’t automatically mean we’ll have to cancel it. It really depends on your particular situation.

Just be honest with your care team about exactly what you’ve had to eat or drink and when. As long as our team here at UT MD Anderson is aware of it, we can usually make adjustments to your anesthesia regimen or take other measures to reduce your risk.

If a procedure isn’t urgent, we may also opt to do an ultrasound first to examine your stomach’s contents, then decide whether it makes more sense to proceed or reschedule.

Why all of this matters

Our biggest concern with GLP-1s is the possibility of aspiration. That can happen any time you’re under anesthesia, because if your stomach isn’t empty, you may regurgitate or vomit during the procedure and be too sedated to turn your head.

GLP-1s increase the risk of aspiration because they’re designed to delay gastric emptying — which means it takes longer for the food you eat to actually leave your stomach and pass into the small intestines.

Aspiration can be very dangerous. Getting food particles and stomach acid in your lungs can impair your ability to breathe and cause infections, including pneumonia and even sepsis. That’s why we do our best to prevent it.

Other things to know about GLP-1s

If you're due to take a GLP-1 on the day of your surgery, don't worry. You can take it as soon as you've recovered enough from the anesthesia to resume your normal diet. GLP-1s are more of a concern before surgery than afterward.

GLP-1s also shouldn't affect your recovery. The risks associated with that are usually related to glucose control. So, delayed wound healing is more of a concern for patients with high blood sugar.

If you only remember one thing

There’s no question that GLP-1s are wonderful drugs. They’ve helped thousands of people tremendously. But they do carry a certain amount of risk when it comes to anesthesia.

So, it’s very important to let your care team know that you’re on one before you have any type of procedure that requires it.

Shannon Popovich, M.D., is an anesthesiologist at UT MD Anderson.

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