Mounjaro vs Zepbound: What Differs?

Mounjaro vs Zepbound is a question about names more than molecules. Both brands contain tirzepatide, made by Lilly. In the US, the Mounjaro label covers type 2 diabetes, while the Zepbound label covers chronic weight management and obstructive sleep apnea. The dose strengths match. Which one is used, and at what dose, is a decision for you and your prescriber. In the EU and UK, the weight use sits under the Mounjaro name, and the EMA lists no product named Zepbound.

In short

• The US Zepbound prescribing information lists weight management and sleep apnea, while the US Mounjaro prescribing information lists type 2 diabetes.
• Both US labels start at 2.5 mg once weekly and allow a 15 mg adult maximum, with steps after at least 4 weeks.
• The EMA's Mounjaro page lists diabetes and weight management under one brand, and the EMA lists no product named Zepbound.

Mounjaro vs Zepbound: how do the labels compare side by side?

The US prescribing information for Mounjaro and Zepbound shares one active ingredient, tirzepatide, and differs mainly in the approved use and the trial populations behind the side-effect tables. The table below lines up the US label figures and adds the EU and UK position from the EMA and the MHRA.

The two adverse reaction tables come from different trial populations. Do not read one against the other as if the numbers were interchangeable. Sources: the Mounjaro and Zepbound US labels.

Why does the same drug have two names?

Mounjaro and Zepbound are two brand names for tirzepatide, and the sources show the US splitting them by approved use while the EU and UK sources list the uses under Mounjaro. In the US, the Mounjaro label is written for type 2 diabetes and the Zepbound label for weight management and sleep apnea.

The EMA's Mounjaro page lists both type 2 diabetes and weight management under the one brand. The EMA lists no product named Zepbound.

In the UK, the MHRA authorised a new weight-management indication for Mounjaro on 8 November 2023, under the existing brand.

That explains why one person sees one name and another sees the other. The sources show the outcome in each market. They do not explain the reasoning behind it.

Is Zepbound just Mounjaro for weight loss?

Zepbound contains the same molecule as Mounjaro, but its US label is not simply a copy with a new indication. Each label lists uses the other does not.

The US Zepbound label covers chronic weight management alongside a reduced-calorie diet and physical activity, in adults with obesity, or overweight with a weight-related condition. It also covers moderate to severe obstructive sleep apnea in adults with obesity.

The US Mounjaro label covers type 2 diabetes, as an adjunct to diet and exercise, in adults and in children 10 and older. It also lists reducing the risk of major adverse cardiovascular events in adults with type 2 diabetes at high risk.

So the molecule is shared, while the approved uses are not. The EMA's Mounjaro page describes weight management for adults with a BMI of 30 or more, or 27 to under 30 with a weight-related condition.

Do Mounjaro and Zepbound use the same doses and pens?

The two US labels list the same dose strengths: 2.5, 5, 7.5, 10, 12.5 and 15 mg. Both describe single-dose presentations of 0.5 mL and four-dose multi-dose presentations that deliver the same per-injection doses from a 2.4 mL total volume.

The dosing steps are also close. Each label starts at 2.5 mg once weekly, says that dose is not for maintenance, and allows increases in 2.5 mg steps after at least 4 weeks on the current dose.

There are small differences. The Zepbound label holds 2.5 mg for 4 weeks, then moves to 5 mg, and lists maintenance doses of 5, 10 or 15 mg for weight management and 10 or 15 mg for sleep apnea. The Mounjaro label gives a 15 mg weekly maximum in adults and 10 mg in pediatric patients.

These are the labels' own schedules, quoted for comparison. Your prescriber sets your dose. The Zepbound dose chart shows the label's steps as a chart.

For timing at each step, the guide on how long Mounjaro takes to work covers steady state. If you are on Zepbound and want to place your own result, read the week-72 results by dose.

Do Mounjaro and Zepbound have the same side effects?

The US labels report the same kinds of common reactions for both brands, but at different rates because the trials studied different people. The Zepbound table comes from weight management trials. The Mounjaro table comes from type 2 diabetes trials.

For nausea, the Zepbound label reports 8% on placebo and 25%, 29% and 28% at 5, 10 and 15 mg. The Mounjaro label reports 4% on placebo and 12%, 15% and 18% at the same doses.

For vomiting, Zepbound reports 2% on placebo and 8%, 11% and 13%. Mounjaro reports 2% on placebo and 5%, 5% and 9%.

The tables do not show that one brand causes more side effects than the other. They show what each trial population reported at each dose. Within each table, nausea, diarrhea and vomiting are higher on tirzepatide than on placebo.

For how reactions line up across weeks and dose steps, see GLP-1 side effects by week.

What warning signs need a doctor right away?

Both US labels carry the same boxed warning: tirzepatide caused thyroid C-cell tumors in rats, and the relevance to humans is unknown. Both contraindicate use in people with a personal or family history of medullary thyroid carcinoma, or Multiple Endocrine Neoplasia syndrome type 2.

Among the signs the Zepbound Medication Guide lists are:

• Pancreatitis: severe stomach-area pain that does not go away, with or without nausea or vomiting, that may spread to the back. Stop the medicine and call the prescriber right away.
• Serious allergic reaction: swelling of the face, lips, tongue or throat, trouble breathing or swallowing, severe rash or itching, fainting or a very rapid heartbeat. Stop the medicine and get medical help right away.
• Possible thyroid tumor: a lump or swelling in the neck, hoarseness, trouble swallowing or trouble breathing.
• Dehydration or kidney problems: signs of either after vomiting or diarrhea.
• Gallbladder problems: gallbladder symptoms.
• Low blood sugar: a warning when the medicine is used with insulin or sulfonylureas.

This list is not complete. Read the leaflet that comes with your own brand for its full list, and ask your prescriber about anything that worries you.

Is Zepbound sold outside the United States?

The EMA lists no product named Zepbound. Its Mounjaro page lists both type 2 diabetes and weight management under the Mounjaro brand.

In the UK, the MHRA authorised Mounjaro for weight loss and weight management on 8 November 2023, for adults with obesity, or with overweight and a weight-related condition. The MHRA release describes the authorisation under the Mounjaro name and does not mention a Zepbound product.

Brand names and availability differ by country, and these two sources only cover the EU and UK. For any other country, check the national medicines regulator's record for the brand your prescriber names.

Can Dose & Lose track either medicine?

Dose & Lose supports both Mounjaro and Zepbound. The app is a tracker. It does not prescribe, supply or give dosing advice.

You log each dose with the date, time, injection site, a pain rating from 0 to 10 and notes. You can rate symptoms such as nausea from 0 to 10 day by day and see them next to your doses. The app also draws an estimate of the medication level from your logged doses. It is an estimate, not a lab value.

The website has free half-life calculators for Mounjaro and Zepbound. Read more about the Dose & Lose app.

Frequently asked questions

Can a doctor prescribe Mounjaro instead of Zepbound for weight loss?

Prescribers decide, and each label sets what its brand is approved for. In the EU and UK, the Mounjaro sources list weight management. In the US, the Mounjaro label lists type 2 diabetes and Zepbound's lists weight management. Whether either is used outside its label is a decision for the prescriber.

Does Zepbound treat type 2 diabetes?

No, the US Zepbound label does not list type 2 diabetes. Its indications are chronic weight management and moderate to severe obstructive sleep apnea in adults with obesity. Type 2 diabetes is the US Mounjaro label's first-listed use. Both contain tirzepatide, but which brand fits a person is for the prescriber to decide.

Why is there no Zepbound in Europe or the UK?

Because tirzepatide is listed in the EU under the Mounjaro name for both uses. The EMA's Mounjaro page lists diabetes and weight management together and lists no product named Zepbound. In the UK, the MHRA authorised weight management for Mounjaro on 8 November 2023. The sources do not state why the US uses two brands.

Sources

• Zepbound prescribing information (DailyMed): US indication, boxed warning, dose steps, strengths, adverse reactions and warning signs.
• Mounjaro prescribing information (DailyMed): US indication, dose steps, strengths and adverse reactions.
• EMA Mounjaro EPAR: EU indications under the Mounjaro brand.
• MHRA press release on Mounjaro for weight management: UK authorisation date and scope.

Published by Petros IT Solutions SRL under the byline Dose & Lose Editorial Team. Corrections: office@doseandlose.com.