Before You Start a GLP-1: What the FDA Labels Say
This page isn’t medical advice. It has no provider buttons. It sums up what the drug labels tell prescribers and patients, so you know which questions to ask.
Who Shouldn’t Take a GLP-1
- You or someone in your family has had medullary thyroid carcinoma (MTC), a rare thyroid cancer.
- You have multiple endocrine neoplasia syndrome type 2 (MEN 2).
- You’ve had a serious allergic reaction to the drug or to any ingredient in it.
- You’re pregnant. The labels say to stop once a pregnancy is confirmed, because weight loss has no benefit during pregnancy and the drug may harm the baby.
Don’t take two GLP-1 drugs at once. The Foundayo label says so directly. The same goes for tirzepatide, which also acts on the GLP-1 receptor.
The Thyroid Warning on Every GLP-1 Label
The heading reads “Risk of thyroid C-cell tumors.” In studies in rats and mice, these drugs caused thyroid C-cell tumors. Nobody knows yet whether they do the same in people. That’s why a personal or family history of MTC or MEN 2 rules them out.
The labels ask you to tell your prescriber about a lump or swelling in your neck, trouble swallowing, a hoarse voice that doesn’t go away, or shortness of breath.
Tell Your Prescriber About These First
- Pancreatitis, now or in the past. The labels warn about acute pancreatitis.
- Gallbladder problems or gallstones. Fast weight loss raises the risk, and the labels list acute gallbladder disease.
- Kidney disease. Vomiting and diarrhea can dehydrate you and, in some people, injure the kidneys.
- Diabetes treated with insulin or a sulfonylurea such as glipizide. Adding a GLP-1 can push blood sugar too low, so those doses may need to come down.
- Diabetic eye disease (retinopathy). The labels flag faster-than-expected worsening in people with type 2 diabetes.
- Surgery, a colonoscopy or anything else that needs anesthesia or deep sedation. More on that below.
- Pregnancy plans, breastfeeding or birth control pills. Also below.
- Every medicine and supplement you take. GLP-1s slow digestion, which can change how pills by mouth are absorbed.
Pregnancy, Birth Control and Surgery on a GLP-1
- Planning a pregnancy? The Wegovy label says to stop at least 2 months before you try to conceive, because semaglutide stays in the body for weeks. Ozempic’s label says the same. For Zepbound and Foundayo, the labels say to stop once you know you’re pregnant.
- Taking birth control pills with Zepbound or Mounjaro? Tirzepatide can make the pill less reliable. The Zepbound label says to switch to a non-oral method, or add a barrier method such as condoms, for 4 weeks after you start and for 4 weeks after each dose increase.
- Taking birth control pills with Foundayo? Its label gives the same advice for 30 days after you start and 30 days after each dose increase.
- Having surgery or sedation? The labels warn that food can stay in your stomach and be inhaled into the lungs under general anesthesia or deep sedation. Tell the surgeon and the anesthesia team you take a GLP-1, and ask whether to pause it or change how you fast beforehand.
GLP-1 Warnings Compared by Medication
| Warning | Wegovy and Wegovy pill | Zepbound | Foundayo |
|---|---|---|---|
| Thyroid C-cell tumors (boxed) | Yes | Yes | Yes |
| Acute pancreatitis | Yes | Yes | Yes |
| Acute gallbladder disease | Yes | Yes | Yes |
| Severe stomach and bowel reactions | Yes | Yes | Yes |
| Kidney injury from dehydration | Yes | Yes | Yes |
| Low blood sugar | Yes | Yes | Yes |
| Serious allergic reactions | Yes | Yes | Yes |
| Diabetic eye disease getting worse | Yes | Yes | Yes |
| Inhaling food under anesthesia | Yes | Yes | Yes |
| Faster heart rate | Yes | Not listed | Not listed |
| Label revised | June 2026 | August 2026 | July 2026 |
Sources: the Wegovy label, the Zepbound label and the Foundayo label on DailyMed. Ozempic and Mounjaro are approved for type 2 diabetes and carry the same boxed warning. Each medication page has its own details.
If You’re Considering a Compounded GLP-1
As of May 31, 2026, the FDA had received 990 adverse event reports linked to compounded semaglutide and more than 730 linked to compounded tirzepatide. Some patients ended up in the hospital after dosing mistakes, such as drawing the wrong amount from a vial or following a dose schedule that rose faster than the approved one. The FDA also says it doesn’t know whether the salt forms some compounders use, semaglutide sodium and semaglutide acetate, work like the approved drug.
If you go the compounded route, these checks follow from the FDA’s warnings:
- Get the prescription from a licensed clinician who reviews your health history.
- Make sure a state-licensed pharmacy fills it. Ask for its name.
- Check that the dose is written in milligrams and in syringe units, and ask how to measure it if you’re not sure.
- Don’t use a vial that arrives warm or not properly cold.
- Throw out a multi-dose vial 28 days after you first open it.
- Report side effects to the FDA through MedWatch.
Source: FDA’s concerns with unapproved GLP-1 drugs used for weight loss, updated October 1, 2026.
When to Get Medical Help Right Away
- Severe stomach pain that won’t go away, with or without vomiting. It can spread to your back. This can be pancreatitis.
- Pain in the upper right side of your belly, fever, yellow skin or eyes, or clay-colored stools. These can point to a gallbladder problem.
- Swelling of the face, lips, tongue or throat, trouble breathing or swallowing, a bad rash or a racing heartbeat. These are signs of a serious allergic reaction.
- Vomiting or diarrhea that keeps you from drinking enough, or much less urine than usual.
- Shakiness, sweating, confusion or a fast heartbeat if you also take insulin or a sulfonylurea. Your blood sugar may be too low.
- Vision changes if you have type 2 diabetes.
For everyday side effects, like nausea, constipation and fatigue, and how long they last, see our GLP-1 side effects guide.
Where This Information Comes From
Labels
Dates
Not Advice
Updates
Before You Start a GLP-1: FAQ
Can I take a GLP-1 if thyroid cancer runs in my family?
It depends on the type. The labels rule GLP-1s out if you or a family member has had medullary thyroid carcinoma (MTC) or if you have MEN 2. Other thyroid cancers aren’t on that list, but tell your prescriber about any thyroid history.
How long before getting pregnant should I stop Wegovy?
At least 2 months before you plan to conceive, according to the Wegovy label. Semaglutide stays in the body for weeks, so it needs time to clear.
Do GLP-1s affect birth control pills?
Tirzepatide (Zepbound, Mounjaro) and Foundayo can make birth control pills less reliable. Their labels say to switch to a non-oral method, or add a barrier method, for about a month after you start and after each dose increase.
Should I stop my GLP-1 before surgery?
Ask your surgeon and anesthesia team. The labels warn that food can stay in the stomach and be inhaled under general anesthesia or deep sedation, so they need to know you take a GLP-1.
Are compounded GLP-1s as safe as Wegovy or Zepbound?
The FDA can’t say, because it doesn’t review compounded drugs for safety, effectiveness or quality. It has received hundreds of adverse event reports about them, many tied to dosing mistakes.
Looking for More Answers?
View the full GLP-1 FAQ or email us at [email protected]
Medical Disclaimer: This page is for information only and isn’t medical advice. GLP-1 medications require a prescription from a licensed provider, who decides whether treatment is right for you. Compounded semaglutide and tirzepatide are not FDA-approved, and the FDA does not verify their safety, effectiveness or quality.