How Zepbound Overtook Wegovy in the US Weight-Loss Market

Zepbound passed Wegovy in two steps. The first came in the week ending March 8, 2024, when Zepbound recorded 77,590 new US prescriptions, beating Wegovy for the first time since its launch — though Wegovy still led on total prescriptions that week by 25,307 ^[1]. The second step came over the following year: by the week ending April 18, 2025, Zepbound was filling nearly 339,000 prescriptions a week, ahead of Wegovy by 127,000 ^[2], and by March 2026 Lilly held 60.1% of the US incretin market, up from roughly 45% a year earlier ^[4].

The reporting from those years shows several things running alongside the shift. A head-to-head trial found that tirzepatide produced more weight loss than injectable semaglutide ^[3]. Lilly built a direct-to-consumer cash-pay channel and says its LillyDirect self-pay price is a 50% or greater discount versus the list price of other incretin obesity medicines ^[3]. In 2025, CVS Health, one of the largest pharmacy benefit managers in the US, said it would stop covering Zepbound while keeping Wegovy; Lilly shares closed down nearly 12% that day ^[2]. Advertising spending grew on both sides, but Novo spent more, not less, than Lilly ^[6].

When did Zepbound first beat Wegovy on prescriptions?

The crossover happened in the week ending March 8, 2024. Zepbound hit 77,590 new US prescriptions that week, surpassing Wegovy for the first time since Zepbound launched ^[1]. About 6,000 fewer Wegovy prescriptions were filled in the United States that same week ^[1].

The data came from IQVIA and was published by JPMorgan in a weekly note, reported on March 15, 2024 ^[1]. Novo, Lilly and IQVIA did not immediately respond to requests for comment at the time ^[1].

That March 2024 moment was a lead in new prescriptions only. Novo still held the lead in total weekly prescriptions by 25,307 ^[1]. The broader gap opened over the next year: by the week ending April 18, 2025, IQVIA figures reported by Reuters showed nearly 339,000 weekly prescriptions for Zepbound, ahead of Wegovy by 127,000 ^[2].

What is the difference between new and total prescriptions?

New prescriptions count starts — a patient beginning a drug for the first time. Total prescriptions include refills, so they reflect the full base of people already on a medicine ^{[1] [2]}.

This distinction matters when reading market-share claims. In March 2024, Zepbound led on starts while Wegovy still led on the larger measure of total weekly prescriptions by 25,307 ^[1]. By April 2025, the IQVIA weekly figures showed Zepbound ahead of Wegovy by 127,000 prescriptions in a single week ^[2].

Who launched first, Wegovy or Zepbound?

Wegovy was approved in June 2021. Lilly launched Zepbound in the United States in December 2023, more than two years later ^[1].

Both drugs belong to the GLP-1 agonist class, developed from type 2 diabetes medicines, and both reduce food cravings and slow stomach emptying ^[1]. Lilly’s diabetes drug Mounjaro contains the same active ingredient as Zepbound — tirzepatide ^[1].

The stakes were large from the start. In March 2024, analysts saw the market reaching at least $100 billion by the end of the decade, and GlobalData forecast $105 billion by 2029 ^[1]. For scale, Merck’s cancer drug Keytruda was then the world’s top-selling prescription medicine with over $25 billion in annual sales ^[1].

Where does the market share stand now?

Lilly’s share of the US incretin analogs market reached 60.1% by March 2026, up from approximately 45% a year earlier, while the total US market grew 30% in the first quarter of 2026 ^[4]. Internationally, Lilly reached 53.2% share by February 2026 ^[4].

Zepbound alone captured over 50% of the branded incretin obesity-management market by the first quarter of 2026, with US sales of $4.2 billion that quarter, up 80% from the first quarter of 2025, plus $26 million internationally ^[4]. Mounjaro, the tirzepatide diabetes stablemate, delivered $8.7 billion in total sales that quarter — $4.2 billion in the US and $4.4 billion internationally — and approached 51% of the US type 2 diabetes incretin segment ^[4]. For full-year 2025, Zepbound brought in $13.5 billion and Mounjaro $22.97 billion ^[5].

Lilly’s first-quarter 2026 revenue was $19.8 billion, up 56% year over year, with incretin revenue up 90% ^[4]. The company raised its full-year 2026 revenue guidance to $82–85 billion ^[4].

Lilly’s own press release of February 23, 2026 calls Zepbound “the most prescribed weight management medication in 2025” and the “#1 prescribed injectable obesity-management medication” ^[3]. That is a company claim, not an independent audit. A separate estimate points the same way: IQVIA data shared by a Wall Street analyst put Lilly at about 60% of the obesity drug market for 2025 after Zepbound prescriptions overtook Wegovy ^[6]. IQVIA did not respond to a request for comment on that figure ^[6].

What did the head-to-head trial show?

SURMOUNT-5 was a 72-week, multi-center, randomized, open-label Phase 3b trial comparing Zepbound with injectable Wegovy in adults with obesity, or overweight with at least one comorbidity such as hypertension, dyslipidemia, obstructive sleep apnea or cardiovascular disease, who did not have diabetes ^[3].

Participants on Zepbound at their maximum tolerated dose (10 mg or 15 mg) lost an average of 20.2% of body weight, or 50 lbs, compared with 13.7%, or 33 lbs, for those on Wegovy at its maximum tolerated dose (1.7 mg or 2.4 mg) ^[3]. Average starting weights were similar: 248.4 lbs in the Zepbound arm and 250 lbs in the Wegovy arm ^[3]. Reuters framed the same late-2024 readout as Zepbound patients losing 47% more weight than Wegovy patients ^[6].

The trial has limits, and Lilly says so in its own release. It was open-label, not blinded; Lilly describes the data as collected in a less rigorous study with less certain findings, and notes that factors beyond the studied medicines may have contributed to the weight loss ^[3].

The placebo-controlled SURMOUNT-1 trial, run over the same 72 weeks in adults without diabetes, showed average weight loss of 15.0% (34 lbs) on 5 mg, 19.5% (44 lbs) on 10 mg, and 20.9% (48 lbs) on 15 mg, versus 3.1% (7 lbs) for placebo ^[3].

Analysts connected the efficacy gap to the market shift. “When it comes to weight loss, Lilly has that edge with Zepbound,” said Rajiv Leventhal, senior analyst for digital health at Emarketer, who suggested Novo’s higher ad spending was likely an attempt to offset it ^[6].

Did advertising decide the race?

Novo spent more on US advertising, not less. From January through September 2025, Novo spent an estimated $316 million on Wegovy ads (up 54% year over year) and $169 million on Ozempic (up 44%), a combined $487 million — nearly $500 million ^{[6] [7]}. Lilly spent about $131 million on Zepbound in the same nine months, versus $2 million in 2024, and $83 million on Mounjaro, a combined $214 million ^{[6] [7]}.

The figures come from ad tracking firm MediaRadar; both companies declined to comment on their budgets ^[6]. For comparison, AbbVie spent more than $850 million advertising Skyrizi and Rinvoq in those nine months ^[6].

Company and drug	US ad spend, Jan–Sep 2025	Change vs 2024
Novo — Wegovy	$316 million [6] [7]	+54% [6]
Novo — Ozempic	$169 million [6] [7]	+44% [6]
Lilly — Zepbound	$131 million [6] [7]	vs $2 million in 2024 [6]
Lilly — Mounjaro	$83 million [6] [7]	— [6]

Novo halted its ads during the 2024 shortage and ramped them back up in 2025 as supply improved, according to David Moore, Novo’s executive vice president of US operations ^[6].

Lilly’s spending accelerated into 2026. In January 2026 alone, it spent $34 million on five Zepbound TV ads ^[5]. Its “Watch This: Head-to-Head” spot premiered at the 2026 Super Bowl and cited SURMOUNT-5’s 50 lbs versus 33 lbs results directly against Wegovy ^[5].

Spending and share moved in parallel, but the sources do not establish that advertising caused the shift. Rae McMahan, senior vice president of payer solutions at Prescryptive, cautioned that advertising has limits in guiding treatment decisions for these drugs: “It’s still a conversation that needs to be between the patient and their physician” ^[6].

What does Zepbound cost without insurance?

US insurance coverage for these drugs is uneven, which pushes many patients to pay out of pocket ^[6]. Lilly built a channel for exactly that. Through LillyDirect self-pay, patients with a valid prescription can get all Zepbound doses in either a multi-dose KwikPen or a single-dose vial starting at $299 per month for the 2.5 mg dose, as announced on February 23, 2026 ^[3]. Lilly says that self-pay price is a 50% or greater discount compared with the list price of other incretin obesity medicines ^[3].

Lilly reports that over 1 million patients accessed Lilly treatments through LillyDirect in 2025, and that one out of every three new patients starting a branded weight management medication in 2025 was prescribed Zepbound self-pay vials ^[3]. Both figures come from Lilly’s own release and have not been independently audited.

LillyDirect is listed as a pharmacy option in all major electronic health record systems and is open to all US healthcare providers licensed to prescribe Lilly medicines ^[3]. Lilly also partnered with Amazon Pharmacy in March 2024 to deliver prescriptions sent to LillyDirect, including Zepbound ^[1].

Novo moved on the cash-pay side as well. CVS Health retained Wegovy after negotiating a price cut with Novo Nordisk, and Novo forged alliances with three leading telehealth companies to drive self-pay Wegovy sales, as reported in early May 2025 ^[2].

What happened with CVS Caremark and Zepbound coverage in 2025?

In early May 2025, CVS Health — one of the largest pharmacy benefit managers in the US — said it would stop covering Zepbound while retaining Wegovy, which it kept after negotiating a price cut with Novo Nordisk ^[2].

Lilly shares closed down nearly 12% on the news, compounded by the company’s decision not to raise its full-year revenue forecast despite a 45% surge in first-quarter revenue, and a slightly reduced profit prediction ^[2]. At the time, Zepbound’s quarterly sales had quadrupled year over year to $2.31 billion, while Mounjaro had more than doubled to $3.84 billion ^[2].

Lilly CEO David Ricks said he was “not surprised,” given Zepbound is “gaining a lot of market share,” and added: “We’re not interested at all in one of one deals” that reduce access and choice for doctors and patients ^[2]. He argued most of the affected plans were smaller employers, which tend not to cover obesity treatments anyway ^[2].

What the coverage mechanics show is that formulary placement is set by a PBM and a plan, and employers decide what a plan covers — a drug appearing on a list is not the same as a patient’s plan paying for it ^[2].

What about supply, pills and what comes next?

Both drugs were in shortage for much of 2024, and supply improved in 2025 ^[6]. Novo launched a pill version of Wegovy and planned to advertise it immediately and push it through cash-pay, direct-to-consumer channels, according to Moore ^[6].

Lilly’s oral GLP-1, Foundayo (orforglipron), launched in the US in the first quarter of 2026, with broad retail availability by April 9, 2026 ^[4]. More than 12 major telehealth platforms accounted for roughly 35% of launch volume, and more than 80% of Foundayo prescriptions went to patients new to incretin therapy ^[4]. Commercial access was secured at two-thirds of major PBMs by mid-May 2026, with Medicare access planned through a GLP-1 Bridge program beginning July 1 and full consumer promotion from the third quarter of 2026 ^[4].

Behind that, Lilly’s pipeline includes retatrutide, a triple agonist, which showed HbA1c reductions up to 2.0% and body weight reductions up to 16.8% in the TRANSCEND-T2D-1 trial ^[4].

What should a patient know before choosing?

Zepbound is approved for adults with obesity, or overweight with at least one weight-related medical problem, to lose weight and keep it off, and separately for adults with moderate-to-severe obstructive sleep apnea and obesity ^[3]. It must be used with a reduced-calorie diet and increased physical activity, is not for cosmetic weight loss, and its safety and effectiveness in children have not been established ^[3].

Zepbound comes in 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg doses. The 2.5 mg dose is a starting dose, not an approved maintenance dose; the label lists recommended maintenance doses of 5 mg, 10 mg or 15 mg once weekly for weight reduction, and 10 mg or 15 mg for obstructive sleep apnea ^[3]. Which dose is appropriate is a decision for a prescriber.

The label carries warnings shared across this drug class. Zepbound may cause thyroid tumors, including medullary thyroid carcinoma, and is contraindicated for people with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 ^[3]. Other listed serious risks include severe stomach problems, dehydration leading to kidney problems, gallbladder problems, pancreatitis, serious allergic reactions and low blood sugar ^[3].

Zepbound contains tirzepatide and should not be used with other tirzepatide-containing products or any GLP-1 receptor agonist medicine, and a KwikPen should never be shared with another person ^[3].

Finally, coverage is plan-specific. A formulary win or loss by a manufacturer does not determine what any individual’s plan pays; employers and PBMs make those decisions drug by drug ^[2].

Sources

1. Reuters. Lilly weight-loss drug Zepbound new US prescriptions surpass Wegovy for first time. March 15, 2024.
2. pharmaphorum. Lilly hit as PBM drops Zepbound, but retains Wegovy.
3. Eli Lilly and Company. Zepbound (tirzepatide), the most prescribed weight management medication in 2025, now available in multi-dose KwikPen. February 23, 2026.
4. Investing.com. Eli Lilly Q1 2026 slides: incretin dominance drives 56% revenue surge. April 30, 2026.
5. Xtalks. New Zepbound Commercial “Watch This” Highlights Long-Term Impact.
6. Reuters. Novo’s Wegovy and Ozempic US advertising spend doubles rival Eli Lilly, data shows. January 28, 2026.
7. GuruFocus. Novo Nordisk Doubles U.S. Ad Spend on Wegovy, Ozempic. January 29, 2026.
8. IQVIA. Obesity Deep Dive: The Unparalleled Launch Success of Mounjaro and Zepbound. September 23, 2025.
9. Senator Bernie Sanders. Sanders Statement on Eli Lilly’s Decision to Lower the Starter Price of Blockbuster Weight-Loss Drug Zepbound. August 27, 2024.
10. Eli Lilly and Company. Lilly lowers the price of Zepbound (tirzepatide) single-dose vials. December 1, 2025.
11. Truveta Research. Impact of the CVS GLP-1 formulary change: Trends in prescribing. September 5, 2025.
12. CNN. A pharmacy benefit manager stopped covering a GLP-1 for obesity. Now there’s a lawsuit. September 5, 2025.
13. NBC 5 Dallas-Fort Worth. CVS Caremark will cover Lilly’s weight loss drug Zepbound again after patient backlash. May 28, 2026.
14. The Hill. Novo Nordisk sues Eli Lilly over alleged false advertising of weight loss drugs.
15. CNBC. Novo Nordisk CEO defends lawsuit against Eli Lilly: ‘Competition has to be fair.’ August 12, 2026.
16. Fierce Pharma. Article on Lilly’s obesity pill Foundayo and quarterly injectable sales.
17. The Boston Globe. Lilly’s Mounjaro overtakes Keytruda as world’s top-selling drug. May 6, 2026.
18. MediaPost. Report: Lilly & Zepbound Led Pharma Ad Effectiveness During NFL Season. February 3, 2026.
19. Fierce Pharma. The Oral GLP-1 Tracker: Novo’s Wegovy pill, Lilly’s Foundayo continue prescription climb. September 11, 2026.
20. Senate HELP Committee Minority Staff. Promises Made, Promises Broken: Prescription Drug Prices Continue to Skyrocket Under President Trump. April 16, 2026.