How Does Zepbound (Tirzepatide) Work for Weight Loss? Plus 7 More Zepbound FAQs

Zepbound (tirzepatide) is a once-weekly injectable medication that has made headlines since the FDA approved it in 2023. That’s because it can help people who are considered overweight or obese achieve significant weight loss. And losing weight is a health goal for many people.

If you’re just starting Zepbound, your prescriber likely reviewed the basics of the medication with you. Perhaps you’ve had questions since then. How does Zepbound work for weight loss? And how long will it take to see results? Here, we’ll answer those and other frequently asked questions about Zepbound.

Good to know: Zepbound’s manufacturer has a barcode scanning tool online to help you verify that the medication you’re taking is legitimate. Using your phone’s or computer’s camera, scan the barcode on your product. The tool will tell you if it’s authentic Zepbound.

1. How does Zepbound work for weight loss?

Zepbound is unique from other weight-loss injections, such as Wegovy (semaglutide). It’s the first weight-loss medication to target both glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. So it’s known as a dual GIP/GLP-1 receptor agonist.

GIP and GLP-1 are incretin hormones that your body naturally produces. Among other actions, incretins tell your pancreas to release more insulin after eating. They also help balance the production of new glucose (sugar). And, these hormones affect the passage of food through the gut and regulate feelings of hunger.

Incretins send these messages by attaching to their own special binding sites — the GIP and GLP-1 receptors. Zepbound works by imitating your body’s natural GIP and GLP-1 hormones. But the medication’s effects last longer than your body’s natural incretins.

As a result, Zepbound has the following effects:

• Your stomach empties more slowly, causing you to feel fuller for longer.

• Your appetite decreases, and you eat less food.

• The amount of food cravings you have decreases.

• Your pancreas releases more insulin, lowering your blood sugar.

• Your liver does not create as much new sugar.

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Together, these effects lead to weight loss and lower blood sugar levels. That’s why tirzepatide is approved as two separate medications: Zepbound for weight loss and Mounjaro for Type 2 diabetes. Zepbound is also approved for moderate-to-severe obstructive sleep apnea.

2. How long does it take Zepbound to work?

During clinical trials, people taking Zepbound started noticing weight loss about 4 weeks after starting it. This is how long it takes the medication to reach consistent levels in your body. Zepbound’s clinical trial ran for 72 weeks (about 16.5 months). And people continued to lose weight throughout the study. But the greatest results were seen during the first 8 to 9 months of using Zepbound.

3. How long does Zepbound stay in your system?

It takes about 5 days for your body to clear half of Zepbound. This is called its half-life, and it represents when a medication may start wearing off. A half-life also helps experts determine the best dosage for a medication. Zepbound’s half-life of 5 days is why you need to inject it only once a week.

On the flip side, the greater a half-life is, the longer it takes your body to fully clear a medication. In the case of Zepbound, there may be small amounts of it in your system for about 25 days after a dose. This information can be important when it comes to drug interactions. So make sure to include your last Zepbound injection on your medication list when providing it to your healthcare team.

4. How much weight do people lose with Zepbound?

Zepbound is one of the most effective weight-loss medications available. During clinical trials, people lost an average of 15% to 21% of their starting body weight after 72 weeks. In general, people using the highest Zepbound dose (15 mg) lost more weight than those using lower doses (5 mg and 10 mg).

The table below shows clinical trial participants’ average weight loss with different doses of Zepbound after 72 weeks.

EXPERT PICKS: WHAT TO READ NEXT

• Tips for success: Read these pharmacist-backed tips for using Zepbound (tirzepatide) so you can get the most out of your medication.

• What to expect: Learn about notable Zepbound side effects — from nausea to diarrhea — and how to manage them.

• Cost considerations: Find out how much Zepbound costs (with and without insurance), plus ways you can save.

What’s more, longer use of Zepbound can lead to even more weight loss. People in an 88-week (20-month) clinical trial saw continued weight loss with longer use. Participants lost an average of 21% after the first 36 weeks (8 months) and an additional 6% if they continued using Zepbound for another year. This worked out to an average of 26% weight loss after using Zepbound for 20 months.

5. What are the BMI requirements for Zepbound?

Zepbound doesn’t have any body mass index (BMI) requirements included in its manufacturer labeling. You may be eligible for Zepbound if you:

• Are considered obese

• Are considered overweight and have at least one weight-related health condition, such as high cholesterol or high blood pressure

• Have moderate-to-severe obstructive sleep apnea and are considered obese

Some prescribers may use BMI as a way of telling if a person is overweight. People with a BMI of 25 to 29.9 may be considered overweight. And those with a BMI of 30 or higher may be considered obese.

But BMI doesn’t give a complete picture of your body composition or overall health. Your prescriber should also consider the following when deciding if Zepbound is right for you:

• Diet

• Fitness level

• Daily lifestyle

• Medical history

• Genetics

6. How long do you have to take Zepbound?

How long you take Zepbound depends on your health goals. You and your prescriber should work together to determine a length of time that makes sense for you. But Zepbound is intended for long-term use.

Research suggests that people maintain weight loss with continued use of Zepbound. At the end of the clinical trials mentioned above, close to 90% of participants maintained at least 80% of the weight they lost with Zepbound during the first 8 to 9 months (when the greatest weight loss happens).

This study also found that stopping Zepbound can cause you to regain the weight you lost. Participants who switched from Zepbound to placebo (an injection with no medication in it) regained 14% of their body weight. So if you’re going to stop Zepbound, it’s a good idea to develop a plan to help maintain weight loss with your prescriber.

7. Is Zepbound safe?

Yes, for most people, Zepbound is safe when used as directed. But that doesn’t mean it’s free from side effects or risks.

Common Zepbound side effects include:

• Nausea

• Vomiting

• Diarrhea

• Heartburn

• Constipation

• Burping

• Gas

• Stomach pain

• Smaller appetite

Many of the mild side effects are most noticeable shortly after starting Zepbound or raising your dosage. They typically improve or go away after your body adjusts to the medication.

Serious side effects are rare with Zepbound. But people using the medication have reported:

• Low blood sugar

• Pancreatitis (swelling of the pancreas)

• Gallbladder problems, including gallstones

• Kidney damage (usually due to excessive vomiting or diarrhea)

Animal studies have shown that Zepbound may raise the risk of developing thyroid C-cell tumors. These tumors have not been seen in human studies. But to be safe, you shouldn’t use Zepbound if you have personal or family history of medullary thyroid cancer or if you have multiple endocrine neoplasia syndrome type 2 (MEN 2).

Zepbound hasn’t been studied for safety or effectiveness during pregnancy. So if you’re pregnant, it’s not recommended to use Zepbound.

8. Who makes Zepbound?

Eli Lilly makes Zepbound. This is the same company that manufactures the diabetes medication Mounjaro. Eli Lilly makes a number of other well-known medications too, including Trulicity (dulaglutide), Humalog (insulin lispro), and Jardiance (empagliflozin).

How to save on Zepbound

There are ways to save on Zepbound, which is available as a brand-name medication. If you have commercial insurance, you may be eligible to pay as little as $25 for a 1- or 3-month supply of Zepbound pens through the manufacturer’s copay savings program. If your plan doesn’t cover Zepbound, you may be able to pay $499 for a 30-day supply of the pens with the copay card.

Subscribers to GoodRx for Weight Loss can also access FDA-approved, brand-name GLP-1 medications like Zepbound. Lower-cost single-dose vials are also available through LillyDirect for $299 (2.5 mg), $399 (5 mg), and $449 (7.5 mg, 10 mg, 12.5 mg, and 15 mg) per month.

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Written by:

Makita Crawford, PharmD

Makita Crawford, PharmD, has over 15 years of pharmacy experience. She started as a certified pharmacy technician and is now a registered pharmacist.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed 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.

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