What to know about Zepbound and tirzepatide

In this article:

• What is Zepbound?
• How does Zepbound (tirzepatide) work?
• Who can take Zepbound?
• Zepbound facts: What you should know before taking it
• What to know about Zepbound’s side effects
• Zepbound vs. Mounjaro facts
• Tirzepatide vs. semaglutide facts

In this article

• What is Zepbound?
• How does Zepbound (tirzepatide) work?
• Who can take Zepbound?
• Zepbound facts: What you should know before taking it
• What to know about Zepbound’s side effects
• Zepbound vs. Mounjaro facts
• Tirzepatide vs. semaglutide facts

Zepbound is constantly making headlines as one of the newer and most popular “weight-loss jabs.” Zepbound, which contains the active ingredient tirzepatide, is a prescription medicine that is approved by the Food and Drug Administration (FDA) for weight loss as well as obstructive sleep apnea. With the popularity of this drug comes a lot of interest in how it works, safety concerns, and other questions. We’ll detail what you need to know about Zepbound if you’re considering discussing it with your healthcare provider. 

What is Zepbound?

Zepbound is classified as a dual GIP/GLP-1 receptor agonist made by the pharmaceutical company Lilly. Zepbound is used for weight loss and obstructive sleep apnea in certain patients.

This medicine is injected once weekly under the skin of the stomach, thigh, or upper arm. Healthcare providers prescribe Zepbound at the lowest dose, and gradually increase it as needed. 

How does Zepbound (tirzepatide) work?

You likely have heard of GLP-1 agonists like Ozempic and Wegovy. Tirzepatide, which is the active ingredient found in both Mounjaro and Zepbound, is known as a dual GIP/GLP-1 agonist. The scientific name for this type of drug is a glucose-dependent insulinotropic polypeptide (GIP) receptor and glucagon-like peptide-1 (GLP-1) receptor agonist. 

Zepbound is similar to GLP-1 agonists, but works on an additional pathway. For weight loss, Zepbound works on part of the brain involved in appetite regulation. It also slows stomach emptying, which may keep you fuller for longer. Many people also talk about how drugs like Zepbound greatly reduce food noise, which is when you have constant thoughts about food and eating that can interfere with even the best dieting efforts. 

Zepbound is also FDA approved for moderate to severe obstructive sleep apnea (OSA) in adults with obesity. It does not directly treat sleep apnea, however. The way it works for sleep apnea is by promoting weight loss, which helps improve OSA.

Who can take Zepbound?

Zepbound is approved by the FDA for the following:

• Weight loss and chronic weight management in adults with obesity (typically measured by body mass index, or BMI), or adults who are overweight who have at least one weight-related medical condition, such as high blood pressure, high cholesterol, or Type 2 diabetes
• Moderate to severe obstructive sleep apnea in adults with obesity 

Zepbound is typically recommended along with lifestyle changes such as diet and exercise. It is for adults only and is not approved for use in children or adolescents.

Zepbound facts: What you should know before taking it

New drugs like Zepbound are very popular but are not appropriate for everyone. Here are some things you should know if you are considering Zepbound:

• Zepbound is injected once weekly under the skin of the stomach, thigh, or upper arm.
• Zepbound is available in a prefilled pen in the following doses: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. It’s also available directly from Lilly in vials, which require you to draw up the medicine with a syringe. 
• Healthcare providers recommend lifestyle changes along with Zepbound, such as a reduced-calorie diet and increased physical activity.
• Zepbound has a black box warning, which is the most serious warning required by the FDA. This medicine has caused thyroid tumors in animal studies. It’s not known if this risk applies to humans. However, people with a personal or family history of medullary thyroid carcinoma (MTC) or who have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) should not use Zepbound. Anyone using Zepbound should watch for signs of thyroid cancer and call their healthcare provider right away if they have a lump in the neck, hoarseness that won’t go away, or trouble breathing or swallowing.
• Before using Zepbound, it is important to tell your healthcare provider about any medical conditions you have, and if you are pregnant, planning to become pregnant, or breastfeeding. Zepbound should not be used during pregnancy.
• Zepbound may affect how medicines are absorbed when taken around the same time. Ask your healthcare provider if you need to adjust the timing of any of your medicines. Additionally, Zepbound may affect how well birth control pills work. You will need to use an additional type of effective birth control, such as a condom, for four weeks after starting Zepbound—and for four weeks after each dose increase. Talk to your healthcare provider about the best type of birth control for you. 
• If you are having any type of surgery or medical procedure that involves anesthesia or sedation, tell your surgeon that you use Zepbound. This medicine can increase the chance of food or liquid getting into your lungs during a procedure, so your healthcare provider may advise you to stop using Zepbound for several weeks before your procedure. 
• Insurance coverage for Zepbound varies. Some plans may cover it for weight loss, while other plans do not cover weight loss drugs or may require prior authorization. Some insurance plans may cover Zepbound for OSA, but coverage depends on the individual plan. You can call your health insurance plan for more information on coverage and costs. 

What to know about Zepbound’s side effects

The most common side effects are related to the stomach and often go away or lessen as your body adjusts to the medicine. This is one reason why it is especially important to follow the dosing schedule recommended by your healthcare provider—slowly increasing the dose of Zepbound helps your body adjust to the medicine and minimizes side effects. 

Common side effects of Zepbound include:

• Nausea, vomiting, and diarrhea or constipation
• Stomach pain, indigestion, burping, or heartburn
• Tiredness
• Hair loss
• Allergic reactions
• Injection site reactions

Serious side effects are less common but require immediate medical attention. These may include:

• Severe stomach problems, which can cause dehydration and kidney problems
• Gallbladder problems
• Inflammation of the pancreas, or pancreatitis
• Serious allergic reactions
• Hypoglycemia (low blood sugar), especially when Zepbound is used in combination with diabetes medicine(s)
• Vision problems in people with Type 2 diabetes
• Depression or suicidal thoughts

Zepbound vs. Mounjaro facts

Zepbound and Mounjaro are very similar—they contain the same active ingredient (tirzepatide), and have the same dosing, side effects, and warnings. 

The main difference is in their FDA-approved uses. While Zepbound is FDA-approved for weight loss and OSA, Mounjaro is FDA approved for blood sugar control in people with Type 2 diabetes. 

Tirzepatide vs. semaglutide facts

As mentioned above, semaglutide is the active ingredient in the injectable drugs Ozempic and Wegovy—it is also available in oral form under the brand name Rybelsus:

• Ozempic is FDA approved for Type 2 diabetes, cardiovascular risk reduction, and kidney disease. It is also prescribed off-label for weight loss.  
• Wegovy is FDA approved for weight loss and cardiovascular risk reduction.
• Rybelsus is FDA approved for Type 2 diabetes.

Clinical trials have found tirzepatide (the active ingredient in both Zepbound and Mounjaro) to be more effective for weight loss than semaglutide. A 2025 study published in the New England Journal of Medicine found that after 72 weeks, people who used tirzepatide had an average weight loss of 20.2% of their body weight, while those who used semaglutide lost an average of 13.7%.

Bottom line

Zepbound is a weekly injectable drug used for weight loss and obstructive sleep apnea. Clinical studies have found this drug to be effective, especially when used with lifestyle changes like diet and exercise. Consult a healthcare provider for more information about Zepbound and to determine if this medicine is right for you. If you do start treatment, be sure to check in with your healthcare provider regularly, track your progress, and report any side effects.