How Many Americans Take Zepbound or Mounjaro: The Numbers

If you search for how many Americans take Zepbound, you will find a lot of confident-sounding numbers and almost no sources. That is because the number does not exist in the way people assume. No government agency counts users by brand. No major poll publishes a Zepbound-only figure.

What does exist is good data of a different kind: prescription counts, company revenue, market share and survey estimates for the whole GLP-1 class. This page puts those together, says exactly what each one measures, and flags where the estimates get soft.

What is the difference between Mounjaro and Zepbound?

Start here, because almost every confused number downstream comes from this.

Mounjaro and Zepbound are the same drug, tirzepatide, made by Eli Lilly. They are sold under two names because they carry two different FDA approvals:

• Mounjaro is approved for adults with type 2 diabetes.
• Zepbound is approved for chronic weight management, and since December 20, 2024 also for moderate-to-severe obstructive sleep apnea in adults with obesity [1].

Same molecule, different labels, different insurance treatment, different prices. When you see a celebrity say they took Mounjaro and lost weight, that usually means they used the diabetes-labeled product, or they started before Zepbound existed.

One more wrinkle matters for American readers: there is no Zepbound brand in the United Kingdom. Tirzepatide carries the weight-management indication there under the Mounjaro name, which is why British newspapers, British celebrities and the NHS all say “Mounjaro” when they mean weight loss [2]. If you land on a UK article, translate it: UK Mounjaro-for-weight-loss equals US Zepbound.

So how many Americans actually take Zepbound?

The honest answer is that we can bound it, not count it.

Here is what is measured:

Lilly says Zepbound was the most prescribed weight management medication in the United States in 2025. That claim appears in a February 23, 2026 press release and is sourced to IQVIA’s National Prescription Audit data as of December 2025, which IQVIA describes as covering about 94% of US prescriptions [3].

Zepbound produced $13.5 billion in revenue in 2025, up 175% from $4.9 billion in 2024 [4]. In the second quarter of 2026 alone the Zepbound line brought in $4.928 billion, of which Lilly reported $4.9 billion in the United States, up 44% [5]. (Tirzepatide is sold for obesity under the Zepbound name in the US, Canada and Japan, so the product line is overwhelmingly but not exclusively American.)

One in three new patients starting a branded weight management medicine in 2025 was prescribed Zepbound self-pay vials, according to the same Lilly release [3].

You can do rough arithmetic from revenue and price, but the result is unreliable because people pay wildly different amounts: $299 cash, $25 with some commercial plans, $50 on Medicare’s new program, or full list price. Treat any single “X million Americans take Zepbound” figure you see online as an estimate someone built the same shaky way. We are not going to add another one.

How many Americans take Mounjaro?

Also uncounted, and harder, because Mounjaro’s revenue is global.

Mounjaro generated $23.0 billion worldwide in 2025, up 99% [4]. In the second quarter of 2026 it reached $9.943 billion worldwide, up 91%, of which $4.8 billion was US [5]. International sales, especially in China, have been growing faster than US sales.

That growth made Mounjaro the world’s best-selling drug in the first quarter of 2026, passing Merck’s cancer drug Keytruda, which had held the title since early 2023 [6].

What percentage of Americans take any GLP-1?

This is the number surveys do publish, and it is the best proxy available.

• KFF, fielded February 24 to March 2, 2026: 12% of US adults currently use a GLP-1 and 6% have used one in the past, for 18% ever-use. The question names Ozempic, Wegovy, Mounjaro, Zepbound, Rybelsus and Trulicity together, without a brand breakdown [7].
• Axios-Ipsos, fielded March 6 to 9, 2026: 18% of adults said they or someone in their immediate circle had taken a weight-loss drug in the past three months [8].
• Gallup, mid-2026: 11% of adults currently take a GLP-1 specifically for weight loss, and 15% have at some point.

The KFF poll also shows how people pay. Among 254 GLP-1 users surveyed, 35% paid the full cost themselves, 44% split it with insurance, and 20% had insurance cover all of it [7].

None of these separate tirzepatide from semaglutide. That is a real gap in US public polling, and it is worth saying plainly rather than papering over.

How big is tirzepatide compared with the whole GLP-1 market?

This is where the picture sharpens.

Lilly’s share of the US incretin market - the industry term for this whole drug class - reached about 60.1% as of March 2026, up from roughly 45% a year earlier [9]. Almost all of that is tirzepatide.

IQVIA’s analysis of the launch gives the underlying mechanics. At 12 months post-launch, Mounjaro and Zepbound had reached about four times as many unique prescribers as Ozempic and Wegovy had at the same stage. Both brands passed $5 billion in first-year sales, which IQVIA says only one drug had ever done before. And US GLP-1 prescriptions of all kinds went from about 2.5 million a month before October 2022 to more than 9 million a month by the end of 2024, with roughly 11 million unique US GLP-1 patients counted in the second quarter of 2025 [10].

So: about 11 million Americans on some GLP-1, and Lilly holding roughly 60% of the class by market share. That is the closest defensible framing.

What does Zepbound actually cost in 2026?

Three prices are in circulation, and they are all real.

List price: roughly $1,086 a month for Zepbound at a retail pharmacy. Almost nobody pays this.

Cash price through LillyDirect: after the December 1, 2025 price cut, $299 a month for the 2.5 mg starting dose, $399 for 5 mg and $449 for every dose from 7.5 mg to 15 mg [11]. Those prices assume you refill within 45 days; let the refill lapse and the maintenance prices are higher. Since late October 2025 the vials can be picked up in person at about 4,600 Walmart pharmacies instead of shipped [12].

Insured price: whatever your plan says, which can be $25 a month, a large coinsurance bill, or nothing at all if your employer excludes weight-loss drugs.

Medicare: the Medicare GLP-1 Bridge, which began July 1, 2026, sets a flat $50 a month for covered weight-management GLP-1s including the Zepbound KwikPen. Single-dose Zepbound pens and vials are not on the covered list [13].

Prices move. Every figure above carries its date for a reason.

Do a lot of people take compounded tirzepatide instead?

Some do, and nobody knows exactly how many.

Gallup’s 2026 survey found that 18% of current GLP-1 users of any brand said they take a compounded or custom-mixed version rather than a brand name. The largest Reddit community dedicated to compounded tirzepatide had about 63,000 members in September 2026.

Lilly has fought this market on two fronts. It has sued more than two dozen med spas, clinics and compounders since 2023. And on March 12, 2026 it published an open letter warning that its testing found significant levels of an impurity in compounded tirzepatide mixed with vitamin B12, which the company said could alter the drug’s toxicity profile [14]. That is Lilly’s claim about products it competes with, and it is worth weighing as such. If you are considering a compounded product, that is a conversation for a licensed healthcare provider, not a comment thread.

Where do people taking these drugs actually talk to each other?

Two Reddit communities dominate:

• r/Zepbound, about 233,650 members as of September 14, 2026 [15]
• r/Mounjaro, about 204,197 members, and explicitly covering both brands [16]

They have their own vocabulary. A “Zepaversary” is a one-year anniversary. “Onederland” is dropping below 200 pounds. “SW / CW / GW” opens almost every milestone post: starting weight, current weight, goal weight. A “stall” is a plateau. And since the summer of 2025, a “forced switch” means being moved off Zepbound by an insurer’s formulary decision.

Those forums are now research material too. In September 2026, University of Pennsylvania researchers published a study in Nature Health that used artificial intelligence to analyze more than 400,000 posts from nearly 70,000 GLP-1 users across five years, finding gastrointestinal complaints most common and fatigue second, plus less-discussed reports of menstrual irregularity and temperature changes.

One caution the researchers themselves raise: people who post are not a representative sample. Milestone posts get upvoted. Quiet quitting does not.

What numbers should you actually trust?

A short hierarchy:

1. Company revenue in Lilly’s quarterly releases. Audited, dated, unambiguous.
2. IQVIA prescription data, when it is cited with a date and a measure. Ask whether it is new prescriptions or total prescriptions - Zepbound crossed those two lines a year apart.
3. KFF, Gallup and Axios-Ipsos polls, for class-level use among adults, with sample sizes and field dates attached.
4. Market-share estimates, which are useful but constructed.
5. Anything that gives you a precise count of US Zepbound users. Be suspicious. That number is not published.

Sources

1. FDA, “FDA approves first medication for obstructive sleep apnea,” December 20, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-medication-obstructive-sleep-apnea
2. The Guardian, “NHS begins mass rollout of weight-loss jabs to patients in England,” June 23, 2025. https://www.theguardian.com/society/2025/jun/23/nhs-begins-mass-rollout-of-weight-loss-jabs-to-patients-in-england
3. Eli Lilly, “Zepbound, the most prescribed weight management medication in 2025, now available in multi-dose KwikPen,” February 23, 2026. https://investor.lilly.com/news-releases/news-release-details/zepbound-tirzepatide-most-prescribed-weight-management
4. Eli Lilly, fourth-quarter and full-year 2025 results, February 4, 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-reports-fourth-quarter-2025-financial-results-and-provides
5. Eli Lilly, second-quarter 2026 results, August 5, 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-reports-second-quarter-2026-financial-results-raises-full
6. The Boston Globe, “Lilly’s Mounjaro overtakes Keytruda as world’s top-selling drug,” May 6, 2026. https://www.bostonglobe.com/2026/05/06/business/lillys-mounjaro-overtakes-keytruda-worlds-top-selling-drug/
7. KFF Health Tracking Poll topline, March 2026. https://files.kff.org/attachment/topline-kff-health-tracking-poll-march-2026.pdf
8. Axios, “GLP-1 use and cost hurdles: Axios-Ipsos poll,” March 19, 2026. https://www.axios.com/2026/03/19/glp-1-use-cost-hurdles-axios-ipsos-poll
9. Investing.com, “Eli Lilly Q1 2026 slides: incretin dominance drives 56% revenue surge,” April 30, 2026. https://www.investing.com/news/company-news/eli-lilly-q1-2026-slides-incretin-dominance-drives-56-revenue-surge-93CH-4650699
10. IQVIA, “Obesity deep dive: the unparalleled launch success of Mounjaro and Zepbound,” September 23, 2025. https://www.iqvia.com/locations/united-states/blogs/2025/09/obesity-deep-dive-the-unparalleled-launch-success-of-mounjaro-and-zepbound
11. Eli Lilly, “Lilly lowers the price of Zepbound single-dose vials,” December 1, 2025. https://investor.lilly.com/news-releases/news-release-details/lilly-lowers-price-zepboundr-tirzepatide-single-dose-vials
12. Walmart, “LillyDirect and Walmart Pharmacy launch first retail pick-up option with direct-to-consumer pricing for Zepbound,” October 29, 2025. https://corporate.walmart.com/news/2025/10/29/lillydirect-and-walmart-pharmacy-launch-first-retail-pick-up-option-with-direct-to-consumer-pricing-for-zepbound
13. CMS, “Medicare GLP-1 Bridge.” https://www.cms.gov/medicare/coverage/prescription-drug-coverage/medicare-glp-1-bridge
14. Eli Lilly, open letter warning of potential patient safety risks, March 12, 2026. https://investor.lilly.com/news-releases/news-release-details/open-letter-eli-lilly-and-company-warning-potential-patient
15. r/Zepbound, member count checked September 14, 2026. https://www.reddit.com/r/Zepbound/
16. r/Mounjaro, member count checked September 14, 2026. https://www.reddit.com/r/Mounjaro/

This page is a guide to public data, not medical advice. It does not tell anyone which medicine to take or at what dose. Talk to a healthcare provider about whether any of these medicines is appropriate for you.