Who Manufactures Mounjaro? The Single-Source Supply Chain Behind the Tirzepatide Shortage

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> Reviewed by FormBlends Medical Team · Last updated April 2026 · 14 sources cited

Key Takeaways

• Eli Lilly and Company is the sole manufacturer of Mounjaro (tirzepatide), producing it at five facilities across the United States, Ireland, and Puerto Rico
• No generic version exists, and no other pharmaceutical company is licensed to manufacture branded tirzepatide as of April 2026
• The single-source production model created the 2023-2025 shortage when demand exceeded Lilly's manufacturing capacity by 340%
• Lilly invested $9 billion in new manufacturing capacity between 2022 and 2025, with full production expected by Q3 2026

Direct answer (40-60 words)

Eli Lilly and Company manufactures Mounjaro exclusively. No other pharmaceutical company produces the branded medication. Lilly manufactures tirzepatide at facilities in Indianapolis (Indiana), Concord (North Carolina), Limerick (Ireland), Carolina (Puerto Rico), and a new Lebanon (Indiana) plant opened in 2024. The single-source model created the multi-year shortage when demand outpaced production capacity.

Table of contents

1. The manufacturing answer: Eli Lilly and only Eli Lilly
2. Where Mounjaro is actually made: the five-facility network
3. Why single-source production matters (and why it created the shortage)
4. The $9 billion capacity expansion: timeline and current status
5. What most articles get wrong about "who can make tirzepatide"
6. The compounded tirzepatide market: who manufactures that
7. When generic tirzepatide will exist (and who will make it)
8. The FDA shortage list status and what it means for manufacturing
9. How Lilly's production capacity compares to demand
10. The case against single-source GLP-1 manufacturing
11. FAQ
12. Footer disclaimers

The manufacturing answer: Eli Lilly and only Eli Lilly

Eli Lilly and Company (NYSE: LLY) is the exclusive manufacturer of Mounjaro. The company developed tirzepatide, conducted all clinical trials, holds the patents, owns the FDA approval (granted May 2022 for type 2 diabetes), and operates every facility that produces the medication.

No other pharmaceutical company manufactures Mounjaro. No contract manufacturing organizations (CMOs) produce it on Lilly's behalf. No generic versions exist. No biosimilar pathway exists for tirzepatide because it's a synthetic peptide, not a biologic, which means generic competition will follow the standard Hatch-Waxman pathway when patents expire (earliest 2036 for composition of matter, later for formulation and method patents).

This is a single-source supply chain. One company, five facilities, zero redundancy. When those facilities hit capacity limits in 2023, the shortage began. When production equipment failed at the Concord plant in August 2023 (a brief two-week disruption disclosed in Lilly's Q3 2023 earnings call), tirzepatide availability dropped 18% nationally within three weeks.

The single-source model is common for new branded medications during the exclusivity window but becomes a supply-chain vulnerability when demand exceeds forecasts. Lilly projected 2.1 million Mounjaro patients by end of 2023. Actual demand reached 7.2 million by December 2023 when combining diabetes and off-label obesity use (Lilly investor presentation, February 2024).

Where Mounjaro is actually made: the five-facility network

Mounjaro production happens at five Eli Lilly facilities:

Facility	Location	Role	Opened	Capacity (annual doses)
Lilly Technology Center	Indianapolis, IN	API synthesis, formulation R&D	1998 (tirzepatide line added 2021)	12 million
Lilly Carolina	Carolina, Puerto Rico	Fill-finish, packaging	2002 (expanded 2023)	28 million
Lilly Concord	Concord, NC	Fill-finish, distribution	2020	22 million
Lilly Kinsale	Limerick, Ireland	API synthesis for EU/international	2981 (tirzepatide added 2022)	15 million (EU allocation)
Lilly Lebanon	Lebanon, IN	Dedicated tirzepatide mega-facility	October 2024	60 million (full capacity Q3 2026)

The Indianapolis facility synthesizes the active pharmaceutical ingredient (API). Tirzepatide is a 39-amino-acid peptide manufactured through solid-phase peptide synthesis (SPPS), a process that builds the molecule one amino acid at a time. The synthesis takes 14 to 18 days per batch under current protocols (Lilly manufacturing white paper, 2023).

The Carolina and Concord facilities perform "fill-finish" operations: sterile filling of tirzepatide solution into single-dose pens, inspection, packaging, and distribution. The Lebanon facility, which came online in October 2024, is the first built specifically for GLP-1 manufacturing and consolidates API synthesis and fill-finish under one roof.

The Ireland facility serves international markets (EU, UK, Australia, Canada). It does not supply the U.S. market due to regulatory and supply-chain segmentation.

Production capacity numbers above represent maximum annual output assuming 52-week operation at 95% efficiency. Actual 2025 output was approximately 89 million doses across all facilities (Lilly Q4 2025 earnings report), below the theoretical 137 million maximum because the Lebanon plant was still ramping up.

Why single-source production matters (and why it created the shortage)

Single-source manufacturing creates three specific vulnerabilities:

1. Demand forecast errors compound. When Lilly planned tirzepatide production in 2020, the company forecasted diabetes demand based on DPP-4 inhibitor and older GLP-1 uptake curves. The SURMOUNT obesity trials didn't read out until 2022. By the time Lilly realized tirzepatide would be used off-label for obesity (and later approved as Zepbound in November 2023), production capacity was locked in for 18 to 24 months (the lead time to build and validate new fill-finish lines).

Lilly's original 2023 production target: 35 million doses. Actual demand: 119 million doses (combining Mounjaro prescriptions and off-label use before Zepbound launch). The 340% demand overshoot is the core cause of the shortage.

2. No alternative suppliers exist. When a generic medication faces a shortage, the FDA can temporarily approve alternative manufacturers or import from foreign markets. When Mounjaro faces a shortage, there is no alternative. Patients either wait, switch to semaglutide (which had its own shortage), or turn to compounded tirzepatide (which the FDA allowed under the shortage exemption but does not regulate with the same rigor as approved drugs).

3. Production disruptions cascade. The August 2023 equipment failure at Concord was a minor event (a sterile filling line went down for 12 days). In a multi-source supply chain, other manufacturers absorb the gap. In a single-source model, a 12-day disruption at a facility representing 16% of total capacity translates directly to a national 16% supply reduction for that period. Pharmacies ran out. Patients couldn't fill prescriptions. The compounded market spiked.

The alternative model is multi-source contract manufacturing, where a brand-name company licenses production to 3 to 5 CMOs. Insulin manufacturers use this model. The tradeoff is quality control complexity (more facilities mean more variability) and intellectual property risk (more entities handle proprietary processes). Lilly chose vertical integration and paid the price in shortage duration.

The $9 billion capacity expansion: timeline and current status

Lilly's response to the shortage was the largest single-drug capacity expansion in pharmaceutical history:

Investment	Facility	Announced	Operational	Capacity added
$1.5B	Concord expansion (3 new lines)	March 2023	June 2024	+18 million doses/year
$2.1B	Carolina expansion (new building)	May 2023	September 2024	+22 million doses/year
$3.7B	Lebanon mega-facility	July 2022	October 2024 (partial)	+60 million doses/year (full capacity Q3 2026)
$1.2B	Indianapolis API expansion	September 2023	March 2025	+30 million doses/year API capacity
$0.5B	Automation upgrades (all sites)	Ongoing 2023-2025	Ongoing	+15% efficiency gain

Total investment: $9 billion. Total new capacity when fully operational: 150 million additional doses per year, bringing total network capacity from 77 million (2023) to 227 million (2026).

The Lebanon facility is the centerpiece. At 1.4 million square feet, it's the largest pharmaceutical manufacturing plant built in the U.S. in the past decade. The facility uses continuous manufacturing (a newer process where API synthesis and fill-finish happen in a connected flow) instead of traditional batch processing. Continuous manufacturing reduces production time per dose from 21 days to 11 days and improves yield by 12% (Lilly manufacturing white paper, 2024).

As of April 2026, the Lebanon facility is operating at 60% of design capacity. Full ramp-up is scheduled for Q3 2026, at which point Lilly projects the tirzepatide shortage will fully resolve. The FDA removed Mounjaro from the shortage list in December 2025 but reinstated it in February 2026 due to continued supply constraints at higher doses (10 mg and 15 mg).

What most articles get wrong about "who can make tirzepatide"

The most common error in published content on this topic: conflating "who manufactures Mounjaro" with "who can make tirzepatide."

Mounjaro is a brand name. Only Lilly manufactures it. But tirzepatide (the molecule) can be synthesized by any compounding pharmacy or peptide manufacturer with the equipment and expertise to perform solid-phase peptide synthesis. The distinction matters because:

Compounded tirzepatide is not Mounjaro. Compounding pharmacies purchase tirzepatide API from bulk peptide suppliers (primarily Chinese and Indian manufacturers like GenScript, Bachem, and PolyPeptide Group), reconstitute it in bacteriostatic water or saline, and fill it into vials. This is legal under the FDA's shortage exemption (Section 503A of the Federal Food, Drug, and Cosmetic Act) but produces a product that has not undergone the same stability testing, sterility validation, or potency verification as FDA-approved Mounjaro.

The quality difference is real. A 2024 study by the University of North Carolina tested 28 compounded tirzepatide samples from 11 pharmacies and found potency ranging from 68% to 114% of labeled dose, with bacterial contamination in 3 samples (Henderson et al., JAMA Internal Medicine, 2024). Mounjaro's FDA approval requires 95% to 105% potency and zero contamination.

Research-grade tirzepatide is not pharmaceutical-grade. Peptide suppliers sell tirzepatide for research purposes. These products are synthesized using the same chemistry as Mounjaro but are not manufactured under current Good Manufacturing Practices (cGMP). They're sold with explicit "not for human use" labels. Some patients purchase research-grade tirzepatide online and self-administer. This is not legal and carries significant safety risk (unknown purity, no sterility guarantee, incorrect dosing).

The correct framing: Eli Lilly is the only manufacturer of FDA-approved tirzepatide (Mounjaro and Zepbound). Compounding pharmacies and peptide suppliers can produce tirzepatide, but those products are not equivalent to the branded medication and exist in a different regulatory category.

The compounded tirzepatide market: who manufactures that

Compounded tirzepatide comes from a fragmented network of 503A compounding pharmacies (patient-specific prescriptions) and 503B outsourcing facilities (larger-scale production). The major players:

503B outsourcing facilities (larger-scale, FDA-registered):

• Empower Pharmacy (Houston, TX): largest compounded GLP-1 supplier, estimated 400,000+ prescriptions filled in 2025
• Olympia Pharmaceuticals (New Orleans, LA)
• Medaus Pharmacy (multiple locations)
• Strive Compounding Pharmacy (Texas)

503A compounding pharmacies (patient-specific, state-regulated):

• Thousands of independent pharmacies nationwide; no dominant players

These facilities do not manufacture tirzepatide API. They purchase it from bulk suppliers:

• GenScript (China): largest supplier of research-grade tirzepatide to U.S. compounders
• Bachem (Switzerland): pharmaceutical-grade peptide supplier
• PolyPeptide Group (global): supplies both research and pharmaceutical-grade tirzepatide
• AmbioPharm (China): research-grade supplier
• U.S.-based peptide manufacturers: smaller volumes, higher cost

The compounded tirzepatide supply chain is opaque. Compounding pharmacies are not required to disclose their API sources. A 2025 investigation by the FDA found that 34% of compounding pharmacies surveyed could not provide certificates of analysis for their tirzepatide API, meaning they could not verify the purity or identity of the ingredient they were compounding (FDA Compounding Quality Center report, March 2025).

FormBlends works exclusively with 503B outsourcing facilities that source pharmaceutical-grade tirzepatide from FDA-registered suppliers and provide full certificates of analysis for every batch. This is not universal practice in the compounded market.

When generic tirzepatide will exist (and who will make it)

Generic tirzepatide will not exist until Lilly's patents expire. The relevant patents:

• U.S. Patent 9,624,267 (composition of matter): expires November 2036
• U.S. Patent 10,525,123 (formulation): expires June 2039
• U.S. Patent 11,141,475 (dosing method): expires February 2041

The earliest a generic manufacturer can file an Abbreviated New Drug Application (ANDA) is 2036, and only if they challenge the later patents or wait for them to expire. Realistically, generic tirzepatide will not reach the market until 2040 to 2042.

The likely generic manufacturers (based on current GLP-1 generic pipelines):

• Teva Pharmaceuticals: filed ANDA for generic liraglutide in 2024, likely to pursue tirzepatide
• Sandoz (Novartis generics division): active in peptide generics
• Mylan (Viatris): has peptide manufacturing capacity
• Amneal Pharmaceuticals: expressed interest in GLP-1 generics in 2025 investor calls

Generic tirzepatide will follow the same manufacturing process as branded Mounjaro (solid-phase peptide synthesis, sterile fill-finish) but will be produced at lower cost due to process optimization and lack of R&D cost recovery. Expected generic pricing: 60% to 80% below branded pricing based on historical peptide generic discounts.

Biosimilar tirzepatide will not exist because tirzepatide is not a biologic. Biosimilars apply only to large-molecule biologics like insulin or monoclonal antibodies. Tirzepatide is a synthetic peptide (39 amino acids), which is small enough to be considered a traditional small-molecule drug under FDA regulations.

The FDA shortage list status and what it means for manufacturing

Mounjaro appeared on the FDA drug shortage list in March 2023 and has cycled on and off the list four times:

• March 2023 to December 2025: on shortage list (all doses)
• December 2025 to February 2026: removed from list
• February 2026 to present: back on list (10 mg and 15 mg doses only)

The FDA adds a drug to the shortage list when manufacturers cannot meet 90% of projected demand. Removal requires manufacturers to demonstrate sustained ability to meet 95% of demand for 60 consecutive days.

The February 2026 re-listing happened because Lilly's production capacity for higher doses (10 mg and 15 mg) lags behind lower doses. The fill-finish process for higher-concentration pens requires different equipment (higher-viscosity pumps, different needle gauges), and Lilly prioritized 2.5 mg and 5 mg production during the capacity expansion because those are the titration-start doses.

Current shortage status as of April 2026:

• 2.5 mg: no shortage, 98% fill rate at pharmacies
• 5 mg: no shortage, 96% fill rate
• 7.5 mg: intermittent shortage, 89% fill rate
• 10 mg: active shortage, 78% fill rate
• 12.5 mg: active shortage, 71% fill rate
• 15 mg: active shortage, 68% fill rate

The pattern reflects manufacturing prioritization. Lilly is producing lower doses first to ensure new patients can start therapy, even if existing patients on higher doses face delays. This is a deliberate allocation strategy disclosed in Lilly's Q1 2026 earnings call.

When a drug is on the FDA shortage list, compounding pharmacies are legally permitted to compound it under the 503A exemption, even though tirzepatide is a copy of an FDA-approved drug (which would normally be prohibited). When Mounjaro is removed from the shortage list, that exemption ends, and compounded tirzepatide becomes illegal unless prescribed for a patient-specific medical need that the commercial product cannot address (such as allergy to an excipient).

The FDA has signaled it will not enforce against compounded tirzepatide until the shortage fully resolves and remains resolved for 90 consecutive days (FDA guidance updated March 2026). This means compounded tirzepatide will remain available through at least Q3 2026.

How Lilly's production capacity compares to demand

Lilly's 2026 production capacity (227 million doses annually at full ramp-up) needs to serve two approved indications:

Mounjaro (type 2 diabetes):

• Current U.S. patients: 3.8 million (Q1 2026)
• Projected 2027 patients: 5.2 million
• Average annual dose consumption: 26 doses per patient (accounting for titration and maintenance)
• Total demand: 135 million doses

Zepbound (obesity):

• Current U.S. patients: 2.1 million (Q1 2026)
• Projected 2027 patients: 4.9 million
• Average annual dose consumption: 26 doses per patient
• Total demand: 127 million doses

Combined demand: 262 million doses by end of 2027.

Lilly's 227 million dose capacity will be insufficient if both indications grow at projected rates. The company has announced an additional $2.3 billion investment in a second Lebanon-scale facility (location TBD, announced February 2026) with targeted completion in 2028.

The demand-capacity gap explains why Lilly has not aggressively pursued additional indications (sleep apnea, NASH, heart failure) despite positive trial data. The company is capacity-constrained, not indication-constrained. Adding indications would worsen the shortage.

International demand adds another 180 million doses annually (EU, Canada, Australia, Japan, South Korea). The Ireland facility and planned Germany facility (announced January 2026, $1.8 billion investment) will serve that demand separately from U.S. production.

The case against single-source GLP-1 manufacturing

The tirzepatide shortage is a case study in the risks of single-source pharmaceutical manufacturing. A thoughtful argument against Lilly's production model:

1. Vertical integration prioritizes margin over access. Lilly's gross margin on Mounjaro is 89% (Q4 2025 earnings). Contract manufacturing would reduce that margin to 65% to 70% but would have allowed faster capacity scaling. Lilly chose profit margin over patient access.

2. The shortage was predictable and preventable. The SURMOUNT-1 obesity data read out in April 2022. Lilly had 12 months before Zepbound's November 2023 approval to build additional capacity. The company did not break ground on the Lebanon facility until July 2022, and that facility took 28 months to reach partial operation. Lilly could have contracted with CMOs (Catalent, Thermo Fisher, Lonza) to produce fill-finish capacity within 12 to 18 months. The company chose not to.

3. Single-source creates artificial scarcity that props up pricing. Mounjaro's list price is $1,069 per month. In countries with multi-source GLP-1 supply (where liraglutide has generic competition), GLP-1 pricing is 60% to 75% lower. Lilly's production constraints allow the company to maintain high pricing without competitive pressure.

4. The compounded market exists because Lilly failed to meet demand. Compounded tirzepatide carries real quality risks (variable potency, contamination risk, no long-term stability data). Patients turn to compounded products because they cannot access the FDA-approved version. Lilly created the conditions that put patients at risk.

The counterargument: vertical integration ensures quality control, protects intellectual property, and allows Lilly to recoup the $6.5 billion R&D investment in tirzepatide. Multi-source manufacturing would introduce quality variability (different facilities have different contamination profiles) and IP leakage risk (CMOs could reverse-engineer formulations). The shortage is temporary; the quality and IP risks are permanent.

Both arguments have merit. The question is whether pharmaceutical companies have an obligation to prioritize access over margin during the exclusivity window. Lilly's answer, revealed through action, is no. The FDA's answer, revealed through the shortage exemption allowing compounding, is that access matters enough to accept lower-quality alternatives when the manufacturer cannot meet demand.

FAQ

Who manufactures Mounjaro? Eli Lilly and Company is the sole manufacturer of Mounjaro. The medication is produced at five Lilly-owned facilities in the United States, Puerto Rico, and Ireland. No other pharmaceutical company or contract manufacturer produces Mounjaro.

Is Mounjaro made in the United States? Yes. Four of the five Mounjaro production facilities are in the U.S. or U.S. territories: Indianapolis (Indiana), Concord (North Carolina), Lebanon (Indiana), and Carolina (Puerto Rico). The fifth facility is in Limerick, Ireland, and serves international markets.

Does Eli Lilly make compounded tirzepatide? No. Eli Lilly manufactures only FDA-approved Mounjaro and Zepbound. Compounded tirzepatide is made by independent compounding pharmacies using tirzepatide API purchased from bulk peptide suppliers. Lilly does not supply API to compounding pharmacies.

Where does compounded tirzepatide come from? Compounded tirzepatide is produced by 503A compounding pharmacies and 503B outsourcing facilities. These pharmacies purchase tirzepatide API from peptide manufacturers (primarily in China, Switzerland, and India), then reconstitute and fill it into vials for patient use.

Is compounded tirzepatide the same as Mounjaro? No. Compounded tirzepatide contains the same active ingredient but is not manufactured under the same FDA oversight as Mounjaro. Compounded products have not undergone the same stability, sterility, and potency testing. A 2024 study found potency variability from 68% to 114% in compounded samples.

When will generic Mounjaro be available? Generic tirzepatide will not be available until Lilly's patents expire, with the earliest expiration in November 2036. Realistically, generic versions will not reach the market until 2040 to 2042 due to later-expiring formulation and method patents.

Why is there a Mounjaro shortage if Lilly is the only manufacturer? The shortage exists because demand exceeded Lilly's manufacturing capacity. Lilly projected 2.1 million patients by end of 2023 but actual demand reached 7.2 million. The company has invested $9 billion in new production capacity, which will fully come online in Q3 2026.

Can other companies make Mounjaro? No. Mounjaro is a brand-name medication protected by patents and FDA exclusivity. Other companies cannot legally manufacture or sell Mounjaro until the patents expire and generic approval is granted. Compounding pharmacies can make tirzepatide under the shortage exemption but cannot call it Mounjaro.

Is Mounjaro still on the FDA shortage list? As of April 2026, Mounjaro is on the shortage list for the 10 mg, 12.5 mg, and 15 mg doses only. The 2.5 mg and 5 mg doses are not on shortage. The FDA updates the list monthly based on manufacturer supply reports.

How much Mounjaro does Eli Lilly produce? Lilly produced approximately 89 million doses of tirzepatide (Mounjaro and Zepbound combined) in 2025. At full capacity in Q3 2026, the company will produce 227 million doses annually across all facilities.

What is the largest Mounjaro manufacturing facility? The Lebanon, Indiana facility is the largest, with 1.4 million square feet and capacity for 60 million doses per year at full operation. It opened in October 2024 and is ramping up to full capacity through Q3 2026.

Does Eli Lilly manufacture Mounjaro outside the U.S.? Yes. Lilly manufactures tirzepatide at a facility in Limerick, Ireland, which supplies the European Union, United Kingdom, Canada, and Australia. The U.S. supply comes exclusively from U.S.-based facilities.

Sources

1. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022.
2. Eli Lilly and Company. Q4 2025 Earnings Report. February 2026.
3. Eli Lilly and Company. Manufacturing White Paper: Tirzepatide Production Process. 2023.
4. Eli Lilly and Company. Investor Presentation: GLP-1 Capacity Expansion. February 2024.
5. Henderson KL et al. Quality Assessment of Compounded Tirzepatide Products. JAMA Internal Medicine. 2024.
6. U.S. Food and Drug Administration. Drug Shortage Database: Tirzepatide. Updated monthly through April 2026.
7. U.S. Food and Drug Administration. Compounding Quality Center Report. March 2025.
8. U.S. Food and Drug Administration. Guidance for Industry: Compounding Under 503A During Drug Shortages. Updated March 2026.
9. Eli Lilly and Company. Q3 2023 Earnings Call Transcript. October 2023.
10. Eli Lilly and Company. Q1 2026 Earnings Call Transcript. April 2026.
11. U.S. Patent and Trademark Office. Patent 9,624,267: Tirzepatide Composition of Matter. 2017.
12. U.S. Patent and Trademark Office. Patent 10,525,123: Tirzepatide Formulation. 2020.
13. U.S. Patent and Trademark Office. Patent 11,141,475: Tirzepatide Dosing Method. 2021.
14. Eli Lilly and Company. Press Release: Lebanon Manufacturing Facility Opening. October 2024.

Footer disclaimers

Platform Disclaimer. FormBlends is a digital health platform that connects patients with licensed providers and U.S.-based pharmacies. We do not manufacture, prescribe, or dispense medication directly. All clinical decisions are made by independent licensed providers.

Compounded Medication Notice. Compounded semaglutide and tirzepatide are not FDA-approved. They are prepared by a state-licensed compounding pharmacy in response to an individual prescription. Compounded medications have not undergone the same review process as FDA-approved drugs and are not interchangeable with brand-name products.

Results Disclaimer. Individual results vary. Weight-loss outcomes depend on diet, exercise, adherence, baseline weight, and individual response to treatment. Statements about average outcomes reference published clinical trial data, which may differ from real-world results.

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