Tirzepatide for Sleep Apnea: The SURMOUNT-OSA Results
The FDA's first-ever drug approval for obstructive sleep apnea rests on a trial called SURMOUNT-OSA. Here is what it showed, and what it did not.
For decades, the standard treatment for obstructive sleep apnea (OSA) has been a machine: a CPAP or other positive airway pressure (PAP) device that keeps the airway open during sleep. In December 2024, that changed. The U.S. Food and Drug Administration approved Zepbound (tirzepatide) for moderate-to-severe obstructive sleep apnea in adults with obesity, making it the first-ever medication approved to treat the condition. This explainer walks through what the supporting trial, called SURMOUNT-OSA, actually showed, and where the evidence still leaves open questions.
What sleep apnea is and why weight matters
Obstructive sleep apnea happens when the upper airway repeatedly narrows or collapses during sleep, causing breathing to pause or become shallow. Doctors measure its severity with the apnea-hypopnea index (AHI): the number of these breathing events per hour of sleep. A higher AHI means more disrupted breathing. Excess body weight is a major driver of OSA, and tirzepatide is a weekly injectable that produces substantial weight loss. That is the key idea behind its use here: the drug does not act directly on the airway. It reduces sleep apnea by helping people lose weight.
What the SURMOUNT-OSA trial found
SURMOUNT-OSA was actually two 52-week randomized, double-blind, placebo-controlled trials involving 469 adults who had moderate-to-severe OSA and obesity. One trial (234 participants) enrolled people who were unable or unwilling to use PAP therapy; the other (235 participants) enrolled people already using a PAP device. In both, participants received either tirzepatide or a placebo injection alongside lifestyle changes, and researchers tracked how their AHI changed over a year.
The reductions in breathing events were large. Among participants not using PAP therapy, average AHI fell by about 25 events per hour on tirzepatide, versus about 5 on placebo — an estimated treatment difference of roughly 20 fewer events per hour (95% confidence interval -25.8 to -14.2; P<0.001). Among those already using PAP, average AHI fell by about 29 events per hour on tirzepatide versus about 5.5 on placebo, a difference of about 24 fewer events per hour (95% confidence interval -29.6 to -17.9; P<0.001).
Many participants improved enough to cross into what the researchers described as disease resolution or remission. At the highest tolerated dose, roughly 42% of tirzepatide-treated participants in the non-PAP trial and about 50% in the PAP trial reached OSA remission or mild, non-symptomatic disease, compared with 16% and 14% on placebo. The New England Journal of Medicine's primary report put the top disease-resolution figure at about 51.5%. It is worth being clear about what remission means here: it is defined by AHI thresholds — an AHI below 5, or between 5 and 14 with a low sleepiness score — not a literal cure.
The drug does not act on the airway directly. It reduces sleep apnea by helping people lose weight.
The weight loss underlying these results was considerable. Participants lost about 18% of their body weight (roughly 45 pounds) in the non-PAP trial and about 20% (roughly 50 pounds) in the PAP trial, versus only about 2% on placebo. Beyond breathing, tirzepatide also improved several cardiometabolic markers, with reductions of roughly 40% to 50% in high-sensitivity C-reactive protein (a measure of inflammation) and roughly 7.6 to 9.6 mmHg in systolic blood pressure.
What the approval covers, and its limits
The FDA's approved use is specific: to treat moderate-to-severe obstructive sleep apnea in adults with obesity, used together with a reduced-calorie diet and increased physical activity. The maximum dose is 15 mg injected under the skin once weekly. Both trials required obesity (a body mass index of 30 or higher), so the findings and the approval apply to OSA in adults with obesity — not to people with sleep apnea who are not obese. Because the benefit is mediated by weight loss, it should not be assumed to extend to other groups.
- The drug carries a boxed warning for thyroid C-cell tumors. Medullary thyroid carcinoma was seen in rats; the human risk is unknown. It is contraindicated for people with a personal or family history of medullary thyroid carcinoma or the syndrome MEN 2.
- The most common side effects are gastrointestinalnausea, diarrhea, vomiting, and constipation.
- Remission is defined by AHI thresholds, not a cure. OSA can return if weight is regained or the drug is stopped.
Not a replacement for CPAP
An important point of context comes from the American Academy of Sleep Medicine, which positions tirzepatide as an adjunct that targets the underlying obesity — not a substitute for CPAP or other PAP therapy. The society cautions that CPAP should not be stopped without a proper reassessment, and it notes that stopping tirzepatide may reverse the AHI improvements. In other words, the gains appear to depend on staying on treatment and keeping the weight off.
A few caveats about the evidence itself are worth naming. The primary results were published in the New England Journal of Medicine (Malhotra and colleagues, 2024), but that full text is paywalled; the figures cited here were verified through the journal's published abstract, Lilly's official FDA-approval release, the FDA prescribing information, and reputable secondary outlets quoting the journal's numbers. Reported remission percentages vary slightly depending on how the data are framed and which population is analyzed, which is why you may see figures like 42% and 50% alongside the trial's disease-resolution figure of up to about 51.5%. Note that one widely cited secondary summary swaps the two trials' confidence intervals; the assignments above follow the New England Journal of Medicine's primary report.
The bottom line
SURMOUNT-OSA marked a genuine milestone: the first drug shown in large trials to meaningfully reduce sleep apnea severity, leading to the first FDA approval of a medication for OSA. For adults with obesity and moderate-to-severe sleep apnea, tirzepatide offers a new option that works by driving weight loss and also improves some cardiometabolic markers. But it comes with real limits — an obesity-specific indication, notable warnings and side effects, benefits that may fade if treatment stops, and expert guidance that it complements rather than replaces PAP therapy. Any decision about it belongs with a licensed clinician and, per sleep-medicine guidance, appropriate sleep assessment.
- 01 Malhotra et al., Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity, NEJM, 2024 nejm.org ↗Primary trial publication (abstract). Source of participant counts (469 total; 234 no-PAP, 235 PAP), AHI treatment differences and 95% confidence intervals, and disease-resolution rates.
- 02 Manufacturer release covering remission percentages (up to 50%) and weight-loss figures.
- 03 U.S. FDA approval letter for Zepbound in OSA (217806Orig1s013), Dec 20, 2024 accessdata.fda.gov ↗Announcement of the Dec 20, 2024 approval of Zepbound as the first medication for obstructive sleep apnea.
- 04 DailyMed / FDA Prescribing Information for ZEPBOUND (tirzepatide), 2024 dailymed.nlm.nih.gov ↗Official label: indication, dosing (max 15 mg weekly), boxed warning, contraindications, side effects, and the two 52-week trials.
- 05 Professional-society guidance positioning tirzepatide as an adjunct to, not a replacement for, PAP therapy.
- 06 Radcliffe Cardiology, reporting SURMOUNT-OSA cardiometabolic outcomes, 2024 radcliffecardiology.com ↗Secondary source for hsCRP (40-50%) and systolic blood pressure (7.6-9.6 mmHg) changes. Note: this source swaps the two trials' AHI confidence intervals relative to the NEJM primary report.
Wellness Wire Editorial
The Wellness Wire editorial team. Our explainers are researched from primary sources — clinical-trial reports and FDA labeling — and written for general education. They are not individually reviewed by a clinician and are not a substitute for medical advice.
