Mounjaro vs Zepbound: Same Drug, Different Labels (and Prices)

Mounjaro and Zepbound are the same medicine: tirzepatide, made by Eli Lilly, sold in the same strengths and the same pens and vials^[1,2]. What differs is the label. In the US, Mounjaro is approved for type 2 diabetes^[1]. Zepbound is approved for weight management and for obstructive sleep apnea in adults with obesity^[2]. That one difference decides who each brand is prescribed for, how insurance and Medicare treat it, and which list price applies.

Label facts have a dotted underline and the date I checked them against the US labels on DailyMed. If you’re comparing tirzepatide with semaglutide instead, that’s in Ozempic vs. Mounjaro. How the whole drug family works is in what GLP-1 medications are.

Mounjaro vs. Zepbound at a glance

Sources: section 1, 2, 3 and the boxed warning of the US labels for Mounjaro^[1] and Zepbound^[2]; approval dates from Drugs@FDA for Mounjaro^[3] and Zepbound^[4]. Prices: Lilly’s pricing information pages, explained below^[16,17].

Why one drug has two brand names

The FDA approves a medicine for specific uses, based on trials in the people it’s meant for. Tirzepatide was first approved in 2022 as Mounjaro, for blood sugar in type 2 diabetes^[3]. The weight-management approval came in 2023 through a separate application, under a new name^[4]. When it announced Zepbound, the FDA noted that its active ingredient was already approved as Mounjaro, and that Zepbound shouldn’t be combined with Mounjaro^[5]. Sleep apnea was added to Zepbound’s label in December 2024^[6].

So each brand carries its own label, its own list price and its own entry on insurance formularies. Medicare shows why that matters:

• The law. Medicare Part D can’t cover drugs used for weight loss, as KFF explains^[9]. Type 2 diabetes and sleep apnea aren’t weight loss, so those uses go through a person’s regular Part D plan, according to CMS^[8].
• The temporary bridge. From July 1, 2026, to December 31, 2027, CMS runs a Medicare GLP-1 Bridge. For weight management it covers the KwikPen form of Zepbound (plus Wegovy and Foundayo) for eligible adults, with a $50 copay. It doesn’t cover Mounjaro for that purpose^[8].

Private plans set their own rules. Your plan’s formulary shows which brand it covers, and for which use.

What the labels share: strengths, pens and vials

Both labels list the same strengths and the same four presentations: single-dose pens, single-dose vials, multi-dose vials and single-patient-use KwikPens; the multi-dose vials and KwikPens hold 4 doses each^[1,2]. So vials aren’t a Zepbound-only option: the current Mounjaro label lists them too^[1].

The dose steps differ only in wording, because the goals differ:

Source: sections 2 and 3 of the US labels for Mounjaro^[1] and Zepbound^[2].

A 5 mg Mounjaro pen and a 5 mg Zepbound pen hold the same molecule at the same strength^[1,2]. Which dose, which presentation and when to change either is your prescriber’s call.

What each brand was tested for

The two brands rest on different trial programs: SURPASS for type 2 diabetes, SURMOUNT for weight^[1,2]. Same molecule, but the numbers can’t be swapped between brands, because the people, goals and lengths differ.

Mounjaro: SURPASS, in type 2 diabetes

• SURPASS-1 (478 adults, 40 weeks, tirzepatide alone vs. placebo). The label reports HbA1c changes of −1.8, −1.7 and −1.7 points on 5, 10 and 15 mg vs. −0.1 on placebo, and weight changes of −6.3, −7.0 and −7.8 kg vs. −1.0 kg^[1]. HbA1c reflects average blood sugar over the past few months.
• SURPASS-2 (1,879 adults on metformin, 40 weeks, vs. semaglutide 1 mg). HbA1c fell 2.01, 2.24 and 2.30 points on tirzepatide 5, 10 and 15 mg, vs. 1.86 points on semaglutide (paper)^[10].
• SURPASS-CVOT (13,299 adults with type 2 diabetes and heart or artery disease, median 4 years, vs. dulaglutide). A heart attack, stroke or cardiovascular death happened in 12.2% on tirzepatide and 13.1% on dulaglutide (hazard ratio 0.92; 95.3% CI 0.83 to 1.01). Tirzepatide was noninferior, meaning not worse, but not shown superior (paper)^[11]. The label added the cardiovascular use in August 2026^[1].

Zepbound: SURMOUNT, in weight management and sleep apnea

• SURMOUNT-1 (2,539 adults without diabetes, 72 weeks). Weight changed by −15.0%, −19.5% and −20.9% on 5, 10 and 15 mg, vs. −3.1% on placebo (paper)^[12].
• SURMOUNT-2 (938 adults with obesity or overweight and type 2 diabetes, 72 weeks). Weight changed by −12.8% on 10 mg and −14.7% on 15 mg, vs. −3.2% on placebo (paper)^[13]. Losses were smaller than without diabetes, which is common in these trials.
• SURMOUNT-OSA (469 adults with moderate to severe sleep apnea and obesity, 52 weeks). The number of breathing interruptions per hour of sleep (the apnea-hypopnea index) fell by 25.3 vs. 5.3 on placebo in people not using CPAP, and by 29.3 vs. 5.5 in people using it (paper)^[14]. More in Zepbound for sleep apnea.

Eli Lilly funded SURPASS-2, SURPASS-CVOT and the SURMOUNT trials^{[10,11,12,13,14]}. You can see the weight results side by side in the trial results chart, and what they mean in practice in how much weight people lose on GLP-1 medications. How Zepbound compares with semaglutide is in Zepbound vs. Wegovy.

Side effects: same molecule, same warnings

Each label has its own table from its own placebo-controlled trials. Mounjaro’s comes from type 2 diabetes trials that averaged about 37 weeks of treatment^[1]. Zepbound’s comes from SURMOUNT-1 and SURMOUNT-2, of up to 72 weeks^[2]. Read the columns as context by population, not as a ranking:

Source: section 6.1 of the US labels for Mounjaro (Table 1, SURPASS-1 and SURPASS-5)^[1] and Zepbound (Table 1, SURMOUNT-1 and SURMOUNT-2)^[2].

Nausea was reported more often in the weight-management trials, but that’s a different population over a longer time, not a sign that one brand is harsher. Both labels say most nausea, vomiting and diarrhea happened during dose increases and decreased over time^[1,2].

The warnings match. Both carry the same boxed warning: thyroid C-cell tumors in rats, of unknown relevance to humans, and a contraindication in people with a personal or family history of medullary thyroid carcinoma or with MEN 2^[1,2]. Both warn about acute pancreatitis, gallbladder disease, kidney injury from dehydration, severe digestive reactions, low blood sugar with insulin or sulfonylureas, diabetic retinopathy complications, and aspiration during anesthesia or deep sedation^[1,2]. Both also say tirzepatide may make birth-control pills less effective, and advise switching to a non-oral method, or adding a barrier method, for 4 weeks after starting and for 4 weeks after each dose increase^[1,2].

If digestive side effects are the problem, I have guides on what to eat with nausea and on constipation. Anything that worries you is worth raising with your doctor.

List prices, and why I don’t rank them

Lilly’s pricing information pages list these prices, which I checked on September 23, 2026^[16,17]. Both are the wholesale acquisition cost as of January 1, 2026: the price Lilly sets before insurance, discounts or rebates^[16,17].

• Mounjaro: $1,112.16 per fill (four pens, a month’s supply)^[16].
• Zepbound: $499 to $1,086.37 per fill (a 28-day supply of up to four pens or vials)^[17]. Lilly publishes it as a range.

I don’t compare which one “costs less.” What you pay depends on your plan, and a plan may cover one brand for its approved use and not the other. The two also aren’t interchangeable on paper, because they’re approved for different conditions. The monthly cost calculator shows the math per dose, every 4 weeks and per year, with each price’s source and date.

Can you switch between Mounjaro and Zepbound?

That’s a decision for your prescriber. Neither label describes switching from one to the other^[1,2]. The Zepbound label says coadministration with other tirzepatide-containing products or with any GLP-1 receptor agonist is not recommended^[2], so the two aren’t meant to be used together. Which brand fits depends on the approved use and on coverage, and your prescriber is the one who weighs that.

What about compounded tirzepatide?

Compounded tirzepatide isn’t Mounjaro or Zepbound. The FDA says compounded drugs aren’t FDA-approved, which means the agency doesn’t review them for safety, effectiveness or quality before they’re sold^[7]. As of May 31, 2026, the FDA had received more than 730 adverse event reports involving compounded tirzepatide, and it says some reports may be related to people prescribed compounded doses beyond what the approved labels allow^[7]. If you’re using or considering one, tell your doctor.

Frequently asked questions

Is Zepbound the same as Mounjaro?

Same molecule, same maker, same strengths and presentations^[1,2]. They’re separate products with separate US labels: Mounjaro for type 2 diabetes (including children 10 and older) and cardiovascular risk in type 2 diabetes, Zepbound for weight management and sleep apnea in adults^[1,2].

Is Mounjaro stronger than Zepbound?

No. Both go from 2.5 mg up to 15 mg once weekly^[1,2] in adults, and a given strength holds the same amount of tirzepatide in either brand. Differences in trial results come from who was studied, not from the brand.

Is Mounjaro approved for weight loss?

Not in the US. Its label covers blood sugar in type 2 diabetes and cardiovascular risk in type 2 diabetes^[1]. Weight did go down in its diabetes trials: in SURPASS-2, the label reports −7.6, −9.3 and −11.2 kg on 5, 10 and 15 mg over 40 weeks^[1]. For weight management, the tirzepatide brand with that approval is Zepbound. Which product fits a given person is for their prescriber to decide.

Can people with type 2 diabetes take Zepbound?

Zepbound’s weight-management use isn’t limited to people without diabetes, and SURMOUNT-2 tested it in adults with type 2 diabetes^[13]. The label warns that using it with insulin or a sulfonylurea may raise the risk of low blood sugar^[2]. Your doctor decides which label fits your situation.

Can teenagers use Mounjaro or Zepbound?

In the US, Mounjaro’s label includes children 10 and older with type 2 diabetes, up to 10 mg once weekly^[1]. Zepbound’s label covers adults only^[2].

What happens if you stop tirzepatide?

On average, much of the weight comes back. In SURMOUNT-4, people who had lost an average of 20.9% in 36 weeks on tirzepatide and were then switched to placebo saw their weight go back up by 14.0% over the next 52 weeks, vs. a further 5.5% drop in those who stayed on it (paper)^[15]. More in what happens when you stop a GLP-1 medication. Stopping is a decision to make with your doctor.