Who Makes Mounjaro and Zepbound? Eli Lilly, Explained

If your pharmacy bag says Mounjaro or Zepbound, one company made what is inside it: Eli Lilly and Company, of Indianapolis, Indiana.

That is the short answer. The longer answer is worth knowing, because the same company sells the same medicine under two names, runs its own online pharmacy, is in the middle of the largest factory-building program in the history of the drug industry, and has been sued by and has sued nearly everyone else in this market. Here is what that means for you.

Who is Eli Lilly?

Eli Lilly and Company was founded on May 10, 1876 by Colonel Eli Lilly, a Civil War veteran and trained chemist. He opened a laboratory in a two-story building near Meridian and Pearl Streets in downtown Indianapolis, with three employees, one of them his 14-year-old son. The room where medicine was actually made was about 160 square feet, roughly the size of a small bedroom [1].

The company has never moved. Headquarters is still Lilly Corporate Center on South Delaware Street in Indianapolis. In 1923 Lilly began selling Iletin, the first commercially available insulin in the United States, which turned diabetes from a fatal disease into a manageable one and made diabetes care the company’s defining business for the next century [2]. Tirzepatide is the most recent chapter of that same story.

As of June 30, 2026, Lilly employed 51,168 people worldwide, including 13,583 in Indianapolis. It runs manufacturing plants in 10 countries and sells medicines in about 90 [2]. In 2025 it reported revenue of $65.2 billion [2].

This matters for one reason many readers care about: Lilly is an American company. Its main rival in this category, Novo Nordisk, which makes Ozempic and Wegovy, is Danish.

What is the difference between Mounjaro and Zepbound?

Both contain tirzepatide. Same molecule, same manufacturer.

The difference is what the FDA approved each one to treat, and therefore what the label says, how insurance treats it, and what it costs.

• Mounjaro is approved for adults with type 2 diabetes, to improve blood sugar control. In August 2026 the FDA also approved it to reduce cardiovascular risk in adults with type 2 diabetes, based on a large head-to-head trial [3].
• Zepbound is approved for chronic weight management in adults with obesity, or overweight with at least one weight-related condition. In December 2024 it also became the first prescription medicine ever approved for moderate-to-severe obstructive sleep apnea in adults with obesity [4].

Drugmakers split brands like this on purpose. Separate brands let a company price, market and negotiate coverage differently for a diabetes use and an obesity use, even when the pills or pens contain the same thing.

One point of confusion worth clearing up for US readers: in the United Kingdom and several other countries, Mounjaro is also the weight-loss brand. There is no Zepbound there. If you have seen British coverage of “Mounjaro for weight loss” and wondered whether you were reading about a different drug, you were not. It is the same medicine under a different commercial arrangement.

Which of these, if any, is right for a particular person is a conversation for them and their healthcare provider. This article is about the company, not about treatment.

Where are Mounjaro and Zepbound actually made?

In more places every year, and increasingly in the United States.

Lilly started building capacity in 2020, before tirzepatide had been approved for anything, on the strength of early trial data [5]. That was a bet: if the data held, the company would need enormous manufacturing capacity; if it did not, it would have built plants for nothing. The data held.

The existing network includes:

• Research Triangle Park and Concord, North Carolina — injectable manufacturing, device assembly and packaging
• Kenosha County, Wisconsin (Pleasant Prairie) — an injectable plant bought from Nexus Pharmaceuticals, then expanded with a $3 billion commitment announced in December 2024, bringing total Wisconsin investment to about $4 billion and adding 750 jobs [6]
• Limerick, Ireland and Alzey, Germany — Lilly’s European manufacturing base [5]
• Indianapolis — existing plants upgraded with about $1.2 billion of investment [5]

The centerpiece is still being built. In Lebanon, Indiana, about 30 miles from headquarters, Lilly is constructing a multi-site campus inside the state’s LEAP Research and Innovation District. It has committed money there five separate times: $2.1 billion in May 2022, $1.6 billion at the 2023 groundbreaking, $5.3 billion in May 2024, $4.5 billion in October 2024 and another $4.5 billion in May 2026 [5][7][8]. Total Lilly capital in the district is roughly $18 billion, and total Indiana commitments since 2020 exceed $21 billion [8].

The Lebanon active-ingredient plant is scheduled to open in 2027. Chief executive David Ricks has said that when it does, “it will be the largest API production site in U.S. history” [8]. API means active pharmaceutical ingredient: the tirzepatide itself, before it is put into a pen or vial.

On top of that, Lilly announced in February 2025 that it would more than double its US manufacturing investment since 2020, taking the total past $50 billion and adding four brand-new American plants [9]. All four have since been named:

Site	Announced	Investment	What it makes
Goochland County, Virginia	September 2025	$5 billion	Cancer and antibody medicines, not GLP-1s
Houston, Texas	September 2025	$6.5 billion	Active ingredients, including orforglipron
Huntsville, Alabama	December 2025	More than $6 billion	Active ingredients, including orforglipron
Fogelsville, Pennsylvania	January 2026	$3.5 billion	Injectable weight-loss medicines, including retatrutide

Lilly has also announced a $3 billion oral-medicine plant in Katwijk, the Netherlands, and more than $1.2 billion to expand its Puerto Rico site.

Two things are worth noticing here. First, not every new Lilly plant is a weight-loss plant; the Virginia site is for cancer and immune-system medicines. Second, the Pennsylvania plant is being built for retatrutide, a drug that has not been approved by any regulator anywhere.

Why does any of this factory-building affect me?

Because of the shortage.

Tirzepatide injection went onto the FDA’s drug shortage list on December 15, 2022 and stayed there for 22 months [10]. During a declared shortage, US law allows compounding pharmacies to make their own versions of a drug. That is why compounded tirzepatide appeared on telehealth sites at a fraction of the brand price, and why so many people started on it.

When Lilly’s capacity caught up, that window closed. The FDA first declared the shortage resolved on October 2, 2024, reconsidered days later after a lawsuit from a compounding industry group, and then reaffirmed the decision in a formal declaratory order on December 19, 2024 [10]. Small compounders had to stop immediately; larger 503B outsourcing facilities were given roughly 60 to 90 days.

The FDA was careful in that order to make a distinction that still matters: a national shortage being over does not mean every pharmacy has every dose in stock on every day. Lilly said the same thing at the time. If your pharmacy cannot fill a particular dose, that is a supply-chain issue between manufacturer, wholesaler and retailer, not necessarily a national shortage.

What is LillyDirect and should I use it?

LillyDirect launched on January 4, 2024. It was the first direct-to-patient platform from a major drugmaker, and it does three things: it sells certain Lilly medicines at a published self-pay price, it lists independent telehealth providers who can evaluate you, and it has a search tool for finding in-person care [11].

Since October 2025 you can also pick up a LillyDirect order at a Walmart pharmacy instead of having it shipped. Walmart operates nearly 4,600 US pharmacies, and Lilly says the price is the same either way [12].

LillyDirect has become a large part of how Americans get Zepbound. Lilly told investors that about 35% of new Zepbound prescriptions in one quarter of 2025 were filled through the self-pay option, and that self-pay accounted for about 45% of Zepbound prescriptions in the first quarter of 2026 [12].

It is a legitimate channel run by the manufacturer, and it removed real friction for people who could not get an appointment with an obesity specialist. It also drew criticism from the start, and you should know what that criticism is.

The American College of Physicians said in January 2024 that it was “concerned by the development of websites that enable patients to order prescription medications directly from the drugmaker,” and argued that telemedicine prescribing should happen within an established patient-physician relationship or in consultation with a doctor who has one [13]. Arthur Caplan, who heads medical ethics at NYU Langone, told NBC News that a drug company using telemedicine to move its own drugs “creates at least the appearance of conflict of interest” [14].

Lilly’s answer is that the telehealth providers listed on LillyDirect are independent, are not paid by Lilly for referrals, are not told which patients came through the platform, and may prescribe any FDA-approved medicine including a competitor’s [11][14].

Both of those things can be true at once. Use the channel if it works for you, but go in knowing whose website it is.

How big is this business for Lilly?

Very big, and that is its own kind of risk.

In 2025, Mounjaro brought in $23.0 billion and Zepbound $13.5 billion. Together they were about 56% of Lilly’s total revenue. In the second quarter of 2026, Mounjaro alone was $9.94 billion and Zepbound $4.93 billion, roughly two thirds of the quarter [15].

Lilly’s own annual report acknowledges that “anti-obesity medicines comprise a significant portion of our revenues” [16]. No large drugmaker in recent memory has depended this heavily on a single molecule. That is why Lilly has spent the last two years buying pipeline companies at a furious pace and building plants for drugs that do not yet exist on the market.

When will there be a generic tirzepatide?

Not soon. Lilly’s 2025 annual report lists the US compound patent for tirzepatide as running to 2036, with data protection to 2027, plus 2037 in major European countries and 2040 in Japan [16].

That is a longer runway than semaglutide, the molecule in Ozempic and Wegovy, whose main US patent expires in the early 2030s. Anything sold online today as generic, compounded or “research grade” tirzepatide is not an FDA-approved version of Mounjaro or Zepbound, and the FDA has not reviewed it for safety, quality or effectiveness.

What should you take away from all this?

Eli Lilly makes both Mounjaro and Zepbound, they contain the same medicine, and the company is spending more than $50 billion in the United States to make more of it. The shortage that created the compounded market is over. LillyDirect is a real channel run by the manufacturer, with the advantages and the conflicts you would expect from that.

None of that tells you whether either drug is right for you. That is a question for a licensed healthcare provider who knows your history.

Sources

1. Milestones of Caring & Discovery — Eli Lilly and Company
2. Key Facts — Eli Lilly and Company
3. FDA approves Lilly’s Mounjaro (tirzepatide) to reduce cardiovascular risk in adults with type 2 diabetes, August 28, 2026
4. FDA approves Zepbound (tirzepatide) for moderate-to-severe obstructive sleep apnea, December 20, 2024
5. Lilly Increases Manufacturing Investment to $9 Billion at Newest Site, May 24, 2024
6. Lilly announces $3 billion expansion of its recently acquired manufacturing facility in Wisconsin, December 5, 2024
7. Lilly to invest another $4.5B in Lebanon site for new ‘medicine foundry’ — Indianapolis Business Journal
8. Lilly commits additional $4.5 billion across Indiana manufacturing sites, May 6, 2026
9. Lilly plans to more than double U.S. manufacturing investment since 2020, exceeding $50 billion, February 26, 2025
10. FDA Declaratory Order: Resolution of Shortages of Tirzepatide Injection Products, December 19, 2024
11. Lilly Launches End-to-End Digital Healthcare Experience through LillyDirect, January 4, 2024
12. LillyDirect and Walmart Pharmacy launch first retail pick-up option, October 29, 2025
13. Eli Lilly weight-loss drug platform draws experts’ concern — Becker’s Hospital Review
14. Eli Lilly launches website to help patients get weight loss drugs — NBC News
15. Lilly reports second-quarter 2026 financial results, August 5, 2026
16. Eli Lilly and Company Form 10-K for the year ended December 31, 2025