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    Tirzepatide

    Also known as Mounjaro, Zepbound, LY3298176

    Tirzepatide is a once-weekly injection from Eli Lilly that activates both the GIP and GLP-1 receptors.[1] Sold as Mounjaro and Zepbound, it produced more weight loss than semaglutide in a head-to-head trial, and by 2026 it was Lilly's largest source of revenue.[2][3]

    Editor reviewedStrict sourcingUpdated GLP-1 and metabolic medicineHealth and medicineLife sciences
    Key facts

    Tirzepatide combines GLP-1 activity with activity at a second incretin receptor, GIP, in one molecule.[1] It is sold as Mounjaro and, for weight management, as Zepbound.[4] In 2026 it drove most of eli-lilly‘s growth.[3]

    Evidence

    In SURMOUNT-1, which enrolled 2,539 adults with obesity and no diabetes, weekly tirzepatide produced mean weight changes of -15.0%, -19.5% and -20.9% at 5, 10 and 15 mg over 72 weeks, versus -3.1% on placebo.[5] In SURMOUNT-5, an open-label head-to-head trial, tirzepatide beat semaglutide: 20.2% versus 13.7% weight loss at 72 weeks.[2] It was also the comparator that Novo’s cagrisema failed to match in REDEFINE 4.[6]

    In SURMOUNT-OSA, tirzepatide cut the apnea-hypopnea index by 25.3 events per hour versus 5.3 on placebo.[7]

    Heart and heart failure

    SURPASS-CVOT compared tirzepatide with dulaglutide, an older GLP-1 drug already shown to cut cardiovascular events, in 13,165 people with type 2 diabetes and heart disease. Tirzepatide was non-inferior but did not show superiority (hazard ratio 0.92).[8] On 28 August 2026 Lilly announced that the FDA had approved Mounjaro to lower the risk of major adverse cardiovascular events in adults with type 2 diabetes at high risk, based on that trial.[9]

    In SUMMIT, 731 people with heart failure with preserved ejection fraction and obesity were randomised to tirzepatide or placebo. Over a median 104 weeks, cardiovascular death or worsening heart failure occurred in 9.9% versus 15.3% (hazard ratio 0.62).[10] A 2026 German health-economic model estimated about EUR 252,611 per quality-adjusted life year for this use at current prices and concluded that large price cuts would be needed for it to be cost-effective.[11]

    Approvals

    The FDA approved Zepbound on 8 November 2023 for chronic weight management in adults with a BMI of 30 or more, or 27 or more with a weight-related condition.[4] On 20 December 2024 it became the first drug approved for moderate-to-severe obstructive sleep apnea in adults with obesity.[12]

    Maintenance

    SURMOUNT-4 tested what happens after treatment stops. Participants who had lost 20.9% over a 36-week lead-in and were then switched to placebo regained 14.0% of body weight over 52 weeks. Those who stayed on tirzepatide lost a further 5.5%.[13] In ATTAIN-MAINTAIN, people who switched from tirzepatide injections to Lilly’s orforglipron pill kept an estimated 74.7% of their weight loss at one year, versus 49.2% on placebo.[14]

    Next-generation combinations

    Tirzepatide is now a comparator and a building block. Novo reported in September 2026 that low-dose cagrisema beat tirzepatide 5 mg, the lowest dose, on weight loss in type 2 diabetes (12.4% vs 9.1%).[15] Lilly reported that adding its amylin agonist eloralintide to tirzepatide produced up to 23.3% weight loss versus 14.8% with tirzepatide 15 mg alone in a phase 2b trial.[16]

    Supply, price and coverage

    The FDA declared the US tirzepatide shortage resolved on 19 December 2024.[17] In April 2026 it proposed barring outsourcing facilities from compounding tirzepatide from bulk ingredients.[18] Under the November 2025 White House agreement, Medicare’s price for Mounjaro and Zepbound was set at $245 a month.[19] Zepbound is covered under Medicare’s GLP-1 Bridge, which started on 1 July 2026.[20] In the second quarter of 2026, Mounjaro revenue was $9.9 billion and Zepbound $4.9 billion. Lilly said lower realised prices for both partly offset rising volumes.[3][21]

    Questions readers ask

    How is tirzepatide different from semaglutide?

    Tirzepatide activates the GIP receptor as well as the GLP-1 receptor. In the open-label SURMOUNT-5 trial it produced 20.2% mean weight loss versus 13.7% with semaglutide at 72 weeks.[1][2]

    Has tirzepatide been shown to reduce heart attacks and strokes?

    In SURPASS-CVOT, among people with type 2 diabetes and heart disease, tirzepatide was non-inferior to dulaglutide, a drug with proven cardiovascular benefit, but superiority was not shown. On that basis the FDA approved Mounjaro in August 2026 to lower cardiovascular risk in adults with type 2 diabetes at high risk.[8][9]

    What happens when people stop tirzepatide?

    In SURMOUNT-4, people switched to placebo after 36 weeks regained 14.0% of body weight over 52 weeks, while those who continued lost a further 5.5%.[13]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      Tirzepatide is a single molecule that activates both the GIP and GLP-1 receptors. confirmedas of 2026-10-10

    2. [2]

      In the open-label SURMOUNT-5 trial, people with obesity but without diabetes lost a mean 20.2% of body weight on tirzepatide versus 13.7% on semaglutide at 72 weeks. confirmedas of 2025-05-11

    3. [3]

      Lilly's second-quarter 2026 revenue rose 48% to $23.0 billion, including $9.9 billion from Mounjaro, $4.9 billion from Zepbound and $98 million from Foundayo. confirmedas of 2026-08-05

    4. [4]

      On 8 November 2023 the FDA approved Zepbound (tirzepatide) for chronic weight management in adults with obesity, or overweight with at least one weight-related condition. confirmedas of 2023-11-08

    5. [5]

      In SURMOUNT-1, which enrolled 2,539 adults with obesity or overweight and no diabetes, weekly tirzepatide produced mean weight changes of -15.0%, -19.5% and -20.9% at doses of 5, 10 and 15 mg at 72 weeks, versus -3.1% with placebo. confirmedas of 2022-06-04

    6. [6]

      On 23 February 2026 Novo Nordisk reported that CagriSema failed to show non-inferiority to tirzepatide 15 mg in the open-label REDEFINE 4 trial, with weight loss of 20.2% versus 23.6% at 84 weeks under the treatment-regimen estimand. confirmedas of 2026-02-23

    7. [7]

      In SURMOUNT-OSA trial 1, tirzepatide reduced the apnea-hypopnea index by 25.3 events per hour at 52 weeks versus 5.3 with placebo in adults with moderate-to-severe sleep apnea and obesity. confirmedas of 2024-06-21

    8. [8]

      In SURPASS-CVOT, tirzepatide was non-inferior but not shown superior to dulaglutide, a GLP-1 drug previously shown to reduce cardiovascular events, for cardiovascular death, heart attack or stroke in 13,165 people with type 2 diabetes and heart disease (hazard ratio 0.92), using a non-inferiority margin of 1.05. confirmedas of 2025-12-01

    9. [9]

      Lilly announced on 28 August 2026 that the FDA approved Mounjaro (tirzepatide) to lower the risk of major adverse cardiovascular events in adults with type 2 diabetes at high risk of them, based on SURPASS-CVOT. confirmedas of 2026-08-28

    10. [10]

      In the SUMMIT trial of 731 people with heart failure with preserved ejection fraction and obesity, tirzepatide lowered the risk of cardiovascular death or worsening heart failure (9.9% vs 15.3%; hazard ratio 0.62) over a median 104 weeks. confirmedas of 2024-11-16

    11. [11]

      A 2026 German health-economic model estimated that tirzepatide for obesity-related heart failure with preserved ejection fraction cost about EUR 252,611 per quality-adjusted life year at current prices, and concluded substantial price cuts would be needed. confirmedas of 2026-05-19

    12. [12]

      On 20 December 2024 the FDA approved Zepbound for moderate to severe obstructive sleep apnea in adults with obesity, the first drug treatment for the condition. confirmedas of 2024-12-20

    13. [13]

      In SURMOUNT-4, people who lost a mean 20.9% during a 36-week tirzepatide lead-in and were then switched to placebo regained 14.0% of body weight over the next 52 weeks, while those who continued lost a further 5.5%. confirmedas of 2024-01-01

    14. [14]

      In the phase 3b ATTAIN-MAINTAIN trial, people who switched from injectable tirzepatide or semaglutide to daily orforglipron kept an estimated 74.7% and 79.3% of their prior weight loss at 52 weeks, versus 49.2% and 37.6% with placebo. confirmedas of 2026-05-13

    15. [15]

      Novo Nordisk reported topline results on 21 September 2026 in which CagriSema 1.0 mg/1.0 mg produced 12.4% weight loss versus 9.1% with tirzepatide 5 mg in type 2 diabetes (REIMAGINE 5), and 21.0% versus 2.0% with placebo in obesity (REDEFINE 9). reportedas of 2026-09-21

    16. [16]

      Lilly reported on 30 September 2026 that in a 48-week phase 2b trial in 367 adults with obesity and type 2 diabetes, its eloralintide (amylin agonist) plus tirzepatide combination produced up to 23.3% weight loss versus 14.8% with tirzepatide 15 mg alone, and that phase 3 trials would start in Q4 2026. reportedas of 2026-09-30

    17. [17]

      The FDA determined on 19 December 2024 that the US shortage of tirzepatide injection had been resolved. confirmedas of 2024-12-19

    18. [18]

      On 30 April 2026 the FDA proposed excluding semaglutide, tirzepatide and liraglutide from the 503B bulks list, which would bar outsourcing facilities from compounding them from bulk ingredients; comments were accepted until 29 June 2026. confirmedas of 2026-04-30

    19. [19]

      Under a 6 November 2025 agreement announced by the White House with Eli Lilly and Novo Nordisk, Medicare prices for Ozempic, Wegovy, Mounjaro and Zepbound were set at $245 a month with a $50 monthly copay for beneficiaries, and Ozempic and Wegovy at $350 through the TrumpRx website. confirmedas of 2025-11-06

    20. [20]

      Novo Nordisk reported that the Bridge programme began on 1 July 2026 and covers a majority of Medicare beneficiaries, and Lilly reported Foundayo and Zepbound coverage under it. confirmedas of 2026-08-05

    21. [21]

      Lilly reported that in the second quarter of 2026 its worldwide revenue rose on a 60% volume increase partly offset by a 13% decrease in realised prices, with US price declines driven mainly by Zepbound and Mounjaro. confirmedas of 2026-08-05

    22. [22]

      Retatrutide is an investigational agonist of three receptors, GIP, GLP-1 and glucagon. confirmedas of 2026-10-10

    Revision history (2)
    1. Page created.
    2. Refresh: added the August 2026 Mounjaro cardiovascular approval, SUMMIT heart-failure results, cost-effectiveness evidence and new combination trials.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Tirzepatide." ContentLora, updated Oct 10, 2026. https://contentlora.com/wiki/tirzepatide

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