Who Shouldn’t Take GLP-1s? Key Precautions and Risks to Consider

Glucagon-like peptide-1 (GLP-1) medications like semaglutide (Ozempic, Wegovy, Rybelsus) and tirzepatide (Mounjaro, Zepbound) have gained attention for their growing list of potential health benefits. You may be wondering if a GLP-1 might be a good fit for you.

But like any medication, GLP-1s aren’t right for everyone. Whether you’re early in your research or already talking with a healthcare professional, it helps to know when a GLP-1 may not be safe to use. Here’s what to consider before getting started.

What are GLP-1s?

GLP-1s are medications that mimic the natural GLP-1 hormone, which plays a role in regulating blood glucose (blood sugar), digestion, and appetite. Some GLP-1 medications, like tirzepatide, also mimic a second hormone called glucose-dependent insulinotropic polypeptide (GIP). 

GLP-1 medications have several effects in the body, including:

• Stimulating the pancreas to release insulin after you eat

• Reducing sugar production in the liver

• Slowing how quickly your stomach empties

• Reducing hunger signals in the brain

GLP-1 medications are approved to treat Type 2 diabetes or help people manage their body weight. Some can also protect the heart and/or kidneys, or treat obstructive sleep apnea. 

Who shouldn’t take GLP-1s?

GLP-1s are considered safe for many people. But there are certain situations where they should be used with caution — or avoided altogether. Your healthcare team will consider your full health history to decide if a GLP-1 is appropriate for you.

Personal or family history of certain thyroid cancers

GLP-1 medications carry a boxed warning (the FDA’s strongest medication warning) due to thyroid C-cell tumors seen in animal studies. This risk hasn’t been confirmed in humans, but it’s taken seriously out of caution.

Because of this, GLP-1s are contraindicated in the following situations, meaning they shouldn’t be used since they may cause harm:

• If you have a personal or family history of medullary thyroid cancer (MTC)

• If you have a diagnosis of multiple endocrine neoplasia syndrome type 2, a rare inherited condition that increases the risk of MTC

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If you’ve had a different type of thyroid cancer, it may be OK to use a GLP-1 medication. Your healthcare team can weigh the potential benefits and risks in your specific situation.

History of pancreatitis

GLP-1 medications have also been linked to acute pancreatitis, which is a sudden inflammation of the pancreas. People with a history of pancreatitis were not included in most GLP-1 clinical trials, so safety data in this group is limited.

The overall risk of pancreatitis with GLP-1s appears to be low. And if you have a history of pancreatitis, some evidence suggests that GLP-1s might actually lower the risk of having another pancreatitis episode. But until more research is available, healthcare professionals tend to avoid GLP-1s in people who’ve had pancreatitis before.

Severe gastrointestinal conditions

GLP-1 medications slow down how quickly food moves out of your stomach, which can help with blood sugar spikes after meals. But this effect can also contribute to common side effects such as nausea and vomiting, bloating, and stomach pain.

In some cases, this slowed digestion has been linked to new or worsening gastroparesis, a condition where the stomach empties too slowly. There have also been rare reports of more serious complications, such as intestinal blockages, especially in people who already have digestive issues.

It’s not known for sure if GLP-1 medications directly cause gastroparesis. But if you have a history of severe gastrointestinal (GI) issues, including severe gastroparesis, GLP-1s may not be a good option. Be sure to discuss any past or current GI symptoms with your healthcare team before starting treatment.

Serious allergic reaction to ingredients

You shouldn’t use a GLP-1 medication if you’ve had a serious allergic reaction to any of its ingredients. While rare, reactions such as anaphylaxis and angioedema (swelling under the skin) have been reported.

Keep in mind that ingredients can vary across GLP-1s. For example, Ozempic and liraglutide injections (Saxenda, Victoza) contain a preservative and propylene glycol (a solvent and stabilizer). Other GLP-1s may not have these ingredients.

If you’ve had an allergic reaction to a GLP-1 medication before, talk to your healthcare team. Depending on the ingredient that caused the reaction, you may still be able to safely try a different GLP-1. Make sure your healthcare team has a list of your known allergies, so they can help you find the safest option.

Pregnancy and nursing

GLP-1s are typically not recommended during pregnancy. There’s limited safety data in pregnant women, and animal studies have shown potential risks to the growing fetus. If you’re thinking about becoming pregnant, your healthcare professional will likely recommend stopping GLP-1 treatment at least 2 months before trying to conceive. This gives your body enough time to clear the medication.

If you become pregnant while using a GLP-1, talk to your healthcare team right away. They can help you safely stop the medication. If you have Type 2 diabetes, they can discuss an alternative treatment, such as insulin, which is considered the preferred and safest option during pregnancy.

There’s also limited safety data on using GLP-1s while nursing. Because of this, your healthcare team may advise against using them in this situation. The manufacturer of Rybelsus, the only oral GLP-1, specifically recommends against taking the medication while nursing.

Other considerations

There are other situations where GLP-1 medications may need to be used with caution or close monitoring. If any of these apply to you, it doesn’t automatically mean you can’t use a GLP-1. But it’s best to discuss them with your healthcare team so they can consider the benefits and risks. Examples include:

• Current or past history of eating disorders, such as anorexia

• Depression or other mood disorders

• History of gallstones

• Eye problems related to diabetes (diabetic retinopathy)

Researchers are still learning about the potential benefits and risks of GLP-1 medications. So there may be other situations where GLP-1s should be used with caution or avoided altogether.

How do you know if GLP-1s are safe for you?

The best way to know if a GLP-1 medication is safe for you is by talking to your healthcare team. They will look at your overall health, medical history, and personal goals to help you weigh the benefits and risks. Here are important points to discuss:

• Your health history: Certain health conditions may increase the risk of complications with GLP-1s. Be sure to share your full medical history so your healthcare professional can make an informed recommendation.

• Allergies: You shouldn’t use a GLP-1 if you’ve had a serious allergic reaction to any of its ingredients. Ingredients can vary by brand, so your healthcare team can check for potential issues based on your allergy list.

• Your pregnancy or family planning goals: GLP-1s typically aren’t recommended during pregnancy and should be stopped at least 2 months before trying to conceive. If you’re planning to become pregnant, this may affect your treatment plan.

Your healthcare team can help ensure that your treatment plan is both safe and effective for your specific needs. If GLP-1s aren’t a good fit, they can guide you toward safer alternatives.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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