Where Is Mounjaro Manufactured? Eli Lilly's Tirzepatide Production Footprint in 2026

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> Reviewed by FormBlends Medical Team · Last updated April 2026 · 10 sources cited

Key Takeaways

• Mounjaro (tirzepatide) is manufactured by Eli Lilly and Company. The drug substance and finished product are made at multiple Lilly plants across the U.S., Ireland, and Germany.
• The active pharmaceutical ingredient (API) is produced primarily at Lilly's Kinsale, Ireland facility and at Lilly's Indianapolis, Indiana site.
• Fill-and-finish (loading the pen and packaging it for shipment) happens at Lilly facilities in Indianapolis, Concord, North Carolina, and at Lilly's Alzey, Germany site.
• Lilly committed over $9 billion in U.S. manufacturing expansion between 2020 and 2024, including the Concord, North Carolina facility, the Lebanon, Indiana site, and the Research Triangle Park API plant.
• Mounjaro and Zepbound are made at the same Lilly facilities. They are the same molecule, distinguished only by labeling and indication.

Direct answer (40-60 words)

Mounjaro is manufactured by Eli Lilly and Company. The active ingredient, tirzepatide, is produced at Lilly's Kinsale, Ireland and Indianapolis, Indiana sites. Fill-and-finish operations (filling the pen, packaging) occur at Lilly's Indianapolis facility, the Concord, North Carolina plant, and the Alzey, Germany plant. The Lebanon, Indiana site adds capacity in 2025 and 2026.

Table of contents

1. Who makes Mounjaro
2. The two production stages: API and fill-finish
3. Tirzepatide API plants (where the molecule is made)
4. Fill-finish plants (where the pen is assembled)
5. Lilly's manufacturing expansion timeline
6. Why supply has been constrained, and where it stands in 2026
7. How U.S. and EU labeling reflects manufacturing location
8. Mounjaro vs Zepbound: same plants, different labels
9. Compounded tirzepatide: who makes that
10. FAQ

Who makes Mounjaro

Mounjaro is manufactured exclusively by Eli Lilly and Company, a U.S.-based pharmaceutical company headquartered in Indianapolis, Indiana. Lilly holds the New Drug Application (NDA) for Mounjaro, granted by the FDA in May 2022 for type 2 diabetes. The drug is patent-protected through approximately 2036 in the U.S., based on the molecular composition patent.

Lilly is the only legal manufacturer of brand-name Mounjaro and Zepbound. No other company makes tirzepatide as a finished pharmaceutical product approved by the FDA. Lilly has not licensed the molecule to generic or biosimilar manufacturers. There is no FDA-approved generic or biosimilar tirzepatide on the market in 2026.

When patients ask "where is Mounjaro manufactured," the answer has two layers: which company (Lilly), and which physical facility (multiple sites across the U.S. and Europe).

The two production stages: API and fill-finish

Pharmaceutical manufacturing of an injectable peptide like tirzepatide happens in two distinct phases at separate facilities.

Stage 1: Active pharmaceutical ingredient (API) production. Tirzepatide is a synthetic peptide composed of 39 amino acids. Lilly produces the API through solid-phase peptide synthesis (SPPS), a process that builds the peptide chain one amino acid at a time on a resin support, then cleaves and purifies it. SPPS is technically demanding and capacity-constrained. Lilly was the only manufacturer of GIP/GLP-1 dual agonists in commercial volume through 2025. Each batch of API takes weeks to produce and meets strict purity, sterility, and chirality specifications under cGMP.

Stage 2: Fill-and-finish. The bulk API is shipped (or transferred internally) to fill-finish facilities, which:

• Reconstitute and dilute the API to the prescribed concentration
• Sterile-filter the bulk solution
• Fill it into single-dose pen cartridges or vials
• Assemble the pen with springs, plungers, and labels
• Inspect each unit
• Package, label, and palletize for shipment

Fill-finish for an autoinjector pen is more capacity-constrained than fill-finish for a simple vial because the pen mechanics require specialized equipment. This was the binding constraint on Mounjaro and Zepbound supply during 2023 and 2024.

Tirzepatide API plants (where the molecule is made)

Lilly produces tirzepatide API at:

Kinsale, Ireland. Lilly's Kinsale facility is the company's largest peptide API site. Lilly invested over $1 billion in Kinsale expansions starting in 2020 specifically for GIP/GLP-1 production. The site supplies API for both U.S. and global markets.

Indianapolis, Indiana (Building 380 and related facilities). Lilly's home campus has long-running peptide API capacity. Tirzepatide API is produced there alongside other Lilly peptides.

Research Triangle Park, North Carolina. Lilly broke ground on a new RTP API facility in 2022. The plant came online in stages through 2024 and 2025 and is dedicated primarily to peptide API including tirzepatide.

Lebanon, Indiana. Lilly's Lebanon, Indiana site is a $9 billion investment announced across multiple phases (2020 onward). It is positioned as a long-term API and fill-finish hub. The first production lines came online in 2025.

The geographic split between Ireland and the U.S. is partly historical (Lilly's long-established Kinsale operation), partly tax-and-trade strategic, and partly redundancy. A multi-site API footprint reduces single-point-of-failure risk.

Fill-finish plants (where the pen is assembled)

After API production, tirzepatide moves to fill-finish facilities. The major Lilly sites:

Indianapolis, Indiana. Lilly's home-campus fill-finish lines have run Mounjaro and Zepbound pens since launch.

Concord, North Carolina. Lilly opened the Concord facility in 2024 specifically for injectable products including tirzepatide. The site is purpose-built for autoinjector pen fill-finish at high volume.

Alzey, Germany. Lilly's Alzey site (acquired and expanded over multiple years) is the European fill-finish hub for Mounjaro pens distributed in the EU. Lilly announced an additional $2.5 billion expansion of the Alzey site in 2024 to add tirzepatide capacity.

Lebanon, Indiana (coming online in stages). The Lebanon site combines API and fill-finish capacity in a single integrated complex. First fill-finish lines were scheduled for 2025-2026 commissioning.

The geographic split between U.S. and EU fill-finish reflects regulatory and logistical realities. Pens distributed in the EU are typically filled in Alzey to meet EU GMP and labeling requirements; pens distributed in the U.S. are typically filled at Concord or Indianapolis.

Lilly's manufacturing expansion timeline

Demand for Mounjaro and Zepbound far outpaced initial Lilly production capacity. The expansion timeline announced publicly:

By the end of 2024, Lilly had announced cumulative manufacturing investments of over $20 billion since 2020, the majority directed at incretin therapy capacity (Mounjaro, Zepbound, and pipeline products).

Why supply has been constrained, and where it stands in 2026

Tirzepatide was on the FDA Drug Shortage List from December 2022 through October 2024 for various doses. The shortage was driven by:

1. Demand growth that exceeded forecasts. Mounjaro launched in 2022 for diabetes; Zepbound launched in late 2023 for weight loss. Combined demand in 2024 was several times what Lilly had forecast at launch.
2. Fill-finish capacity, not API. Pen assembly was the bottleneck. Lilly publicly stated multiple times that API supply was sufficient but that pen-assembly lines were running at full capacity.
3. Quality and sterility requirements. Adding fill-finish capacity for an autoinjector pen is not a 90-day project. New lines require qualification, validation, and regulatory inspection that can take 12 to 24 months.

The shortage was officially resolved in October 2024 once Concord came fully online and Indianapolis added shifts. The FDA removed tirzepatide from the active shortage list with a wind-down period for compounders extending through Q1 2025.

In 2026, Mounjaro and Zepbound supply is generally adequate at U.S. retail pharmacies, with occasional dose-specific tightness during Q1 surges (post-resolution New Year demand).

How U.S. and EU labeling reflects manufacturing location

Patients sometimes ask whether a Mounjaro pen with European labeling is "the same" as a U.S. pen.

The active ingredient and finished product are functionally the same. The differences:

• Labeling language and format. U.S. pens carry FDA-approved labeling in English. EU pens carry EMA-approved labeling, often multilingual.
• Country-of-origin disclosure. U.S. pens typically state "Manufactured by Eli Lilly and Company, Indianapolis, IN" or "Manufactured by Lilly del Caribe, Inc." or similar. EU pens may list Alzey, Germany or another EU site.
• Regulatory bodies. U.S. pens are released under FDA jurisdiction; EU pens under EMA jurisdiction. Both follow comparable cGMP standards.
• Distribution chain. Pens shipped to the U.S. enter U.S. wholesalers (McKesson, Cardinal, AmerisourceBergen) and U.S. retail pharmacies. EU pens follow the parallel EU chain.

Patients should not import EU-labeled Mounjaro into the U.S. through personal mail order. This violates FDA importation rules even though the product is genuine. The risks include seized shipments, lack of recourse for adverse events, and difficulty verifying chain of custody.

Mounjaro vs Zepbound: same plants, different labels

This is the question patients ask second-most often, after "where is it made."

Mounjaro and Zepbound are tirzepatide. Same molecule, same synthesis process, same Lilly facilities. The differences are:

• Indication labeling. Mounjaro is labeled for type 2 diabetes; Zepbound is labeled for chronic weight management.
• Pen color and design. Mounjaro pens are blue-and-grey; Zepbound pens are blue-and-yellow. The mechanism is identical.
• Vials (Zepbound only via LillyDirect). Lilly introduced single-dose vials of Zepbound in 2024 for the Self-Pay program. There is no equivalent Mounjaro vial program.

Both products are made at the same Lilly API and fill-finish facilities. The labeling, packaging, and pen color are the divergence points.

Compounded tirzepatide: who makes that

A separate question patients sometimes have: where is compounded tirzepatide made?

Compounded tirzepatide is not made by Eli Lilly. It is prepared by state-licensed compounding pharmacies (503A) or FDA-registered outsourcing facilities (503B). The active ingredient, raw tirzepatide powder, is sourced from FDA-registered API suppliers. The compounding pharmacy reconstitutes the API into an injectable solution at a specified concentration, fills it into vials, and dispenses it in response to a patient-specific prescription.

503A pharmacies can compound for individual prescriptions. 503B outsourcing facilities can produce in larger batches under more rigorous oversight.

Compounded tirzepatide is not FDA-approved. It is not made at Lilly facilities. It is not Mounjaro or Zepbound, even when the active ingredient is the same molecule.

Patients receiving compounded tirzepatide should expect labeling that identifies the compounding pharmacy by name, license number, and physical address. If the labeling doesn't include those, that's a signal to ask questions before injecting.

FAQ

Where is Mounjaro made? Mounjaro is manufactured by Eli Lilly and Company at multiple facilities. The active ingredient (tirzepatide) is produced primarily at Kinsale, Ireland; Indianapolis, Indiana; Research Triangle Park, North Carolina; and Lebanon, Indiana. Fill-finish (pen assembly) occurs at Indianapolis, Concord, North Carolina, and Alzey, Germany.

Who manufactures Mounjaro? Eli Lilly and Company, a U.S.-based pharmaceutical company headquartered in Indianapolis, Indiana. Lilly is the sole manufacturer; no generics or biosimilars are FDA-approved.

Is Mounjaro made in China? No. Mounjaro is not manufactured in China. The API and finished product are made at Lilly facilities in the U.S., Ireland, and Germany.

Is Mounjaro made in the United States? Yes, partly. Lilly produces Mounjaro API and finished product at multiple U.S. facilities (Indianapolis, Concord NC, Lebanon IN, RTP NC) alongside its Irish and German operations. Pens distributed in the U.S. are typically filled at U.S. sites.

What is tirzepatide made of? Tirzepatide is a synthetic peptide composed of 39 amino acids designed to activate both GIP and GLP-1 receptors. It's manufactured by solid-phase peptide synthesis. The injectable formulation contains tirzepatide plus sodium phosphate (buffer), sodium chloride (tonicity), and metacresol (preservative) in water for injection.

Why is there sometimes a shortage of Mounjaro? Demand for tirzepatide grew faster than Lilly's manufacturing capacity, especially fill-finish (pen assembly) capacity. The FDA listed tirzepatide as in shortage from late 2022 through October 2024. Lilly invested over $20 billion in manufacturing expansion to resolve the shortfall.

Are Mounjaro and Zepbound made at the same factory? Yes. Both products are manufactured at the same Lilly facilities. They are the same molecule (tirzepatide) packaged with different labeling, pen color, and indications.

Is Mounjaro safe if it's manufactured outside the U.S.? Mounjaro made at Lilly's Kinsale (Ireland) or Alzey (Germany) facilities is held to comparable cGMP standards as U.S. production. The FDA inspects foreign Lilly sites that supply U.S. markets. Patients should fill prescriptions at licensed U.S. pharmacies regardless of which Lilly site produced the pen.

Can a generic Mounjaro be made? Not currently. Tirzepatide is patent-protected through approximately 2036 in the U.S. No FDA-approved generic or biosimilar tirzepatide exists in 2026. Compounded tirzepatide is a separate, narrower regulatory pathway.

Where is compounded tirzepatide made? By state-licensed compounding pharmacies (503A) or FDA-registered outsourcing facilities (503B), not by Eli Lilly. The compounding pharmacy's name, license number, and address should appear on the label of any compounded tirzepatide vial.

Why does Lilly have plants in Ireland? Kinsale has been a Lilly site for decades. Ireland is a long-established pharmaceutical manufacturing hub for U.S. companies because of skilled workforce, tax structure, and EU market access. Kinsale is Lilly's largest peptide API facility and supplies both U.S. and global markets.

How can I verify where my Mounjaro pen was made? Read the carton and pen label. Lilly prints the manufacturer's name and address (or distributor and country) on every package. The lot number and country of origin are also encoded for traceability.

Sources

1. U.S. Food and Drug Administration. Mounjaro (tirzepatide) Prescribing Information. Eli Lilly and Company, 2024.
2. U.S. Food and Drug Administration. Zepbound (tirzepatide) Prescribing Information. Eli Lilly and Company, 2024.
3. Eli Lilly and Company. Annual Report (Form 10-K) for fiscal year 2024. Filed with U.S. Securities and Exchange Commission.
4. Eli Lilly and Company. Press release: Lilly to invest $1.6 billion in Lebanon, Indiana manufacturing site. April 2023.
5. Eli Lilly and Company. Press release: Lilly announces $5.3 billion expansion of Lebanon, Indiana site. May 2024.
6. Eli Lilly and Company. Press release: Lilly to invest $2.5 billion in Alzey, Germany site. November 2023.
7. Eli Lilly and Company. Press release: Lilly opens Concord, North Carolina manufacturing facility. 2024.
8. U.S. Food and Drug Administration. FDA Drug Shortage Database, archived entry: tirzepatide injection. Updated October 2024.
9. European Medicines Agency. Mounjaro (tirzepatide) European Public Assessment Report (EPAR). 2022 with annual updates.
10. Frias JP, Davies MJ, Rosenstock J, et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med. 2021;385:503-515.

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