Surgery Journey
Weight-Loss Injections (GLP-1) and Surgery
Weight-Loss and Diabetes Injections and Your Operation
Weekly injections such as semaglutide and tirzepatide, and related daily injections and tablets, are now widely used for diabetes and weight loss. Many patients do not think of them as "medicines", and some buy them online or abroad, so teams do not always hear about them. They matter for surgery because they slow stomach emptying: food can remain in the stomach despite normal fasting, which is dangerous under anesthesia. The key message: tell us about your injection, its dose, and your last dose. Do not stop it on your own; we will give you a clear plan.
Tell Your Team: What They Need to Know
- The name of the medicine and the dose, and whether it is weekly, daily, or a tablet.
- The date of your last dose.
- Whether you started it, or increased the dose, in the last few weeks. The stomach-slowing effect is strongest then.
- Any nausea, vomiting, bloating, or feeling full quickly in the last few days.
- If you bought it online or abroad, say so, and bring the pen or packaging. The dose or content of such products may be uncertain, and the team will treat you as higher risk if the details are unclear.
Your Plan Before Surgery
Guidance has changed quickly and differs between expert groups, but they agree on the main point: most patients continue these medicines before planned surgery. What changes is how the stomach-contents risk is handled:
- If you are at higher risk, for example during dose escalation, on a higher dose, or with stomach symptoms, you may be asked to follow a liquid diet for 24 hours before surgery, or your anesthetic plan may be adjusted. One expert consensus advises extending the fast, including 24 hours without solid food.
- A liquid diet means clear liquids only, such as water, clear juice without pulp, clear soup, and jelly, as instructed.
- The standard fasting rules still apply on the day of surgery.
- Do not stop or change the medicine on your own; follow the plan your hospital gives you, because each hospital adopts one approach and applies it consistently.
- If your stomach is found not to be empty, your operation may be postponed for your safety.
Other Effects to Know About
- Gallstones: these medicines are associated with more gallbladder and bile duct problems. Tell the team about pain in the upper right of your abdomen, especially after fatty meals.
- Nausea and dehydration: reduced intake around surgery can leave you dehydrated; drink as instructed.
- Low blood sugar: if you also take insulin or sulfonylureas, eating less around surgery raises the risk of low sugar, which the team will monitor.
- Muscle and protein: rapid weight loss can reduce muscle and protein stores. Before major surgery, eat enough protein.
- Contraception: tirzepatide can make the contraceptive pill less reliable. Use an additional method, such as condoms, for 4 weeks after starting and after each dose increase.
- Pregnancy: these medicines are stopped before a planned pregnancy; follow your prescriber's advice.
Recovery After Surgery and Restarting
- Feeling sick may be more common for a day or two after the operation. Eat small meals and drink often.
- Restart your medicine when you are eating and drinking normally.
- If you missed several doses, your prescriber may restart at a lower dose to avoid nausea.
- Ramadan: many people take these medicines while fasting, but nausea and drinking less increase dehydration risk. Do not fast while recovering from surgery, and plan any fasting afterward with your prescriber.
Warning Signs: When to Seek Help
Green
- What you notice
- Mild nausea for a day or two after restarting
- What to do
- Expected. Eat small meals and drink often
Amber
- What you notice
- Nausea or vomiting that stops you drinking for 12 hours; upper abdominal pain after fatty meals
- What to do
- Call your doctor or the clinic the same day
Red
- What you notice
- Repeated vomiting, dizziness, or very little urine; severe abdominal pain, especially spreading to the back; yellow eyes or skin; low sugar that does not recover with treatment
- What to do
- Go to the emergency department now
Questions Patients Ask
Do I need to stop my weight-loss injection before surgery?
Usually not. Most current guidance advises continuing it, with a liquid diet the day before for some people. Follow the plan we give you.
Why does it matter for the anesthetic?
These medicines slow how fast your stomach empties. Food can stay in your stomach even after normal fasting, which can be dangerous under anesthesia.
When can I restart it after the operation?
When you are eating and drinking normally. If you missed several doses, your doctor may restart a lower dose.
Full guide written by Dr. Tamer Elalfy