Two 2026 studies differ on whether tirzepatide reduces asthma flare-ups
One analysis links tirzepatide to fewer asthma flare-ups than no treatment, while a larger comparison finds it no better than semaglutide, leaving the respiratory question unresolved for patients.
Adults with obesity who took tirzepatide had fewer asthma flare-ups than similar adults who did not take it, according to a research letter published Feb. 18, 2026 in Clinical & Experimental Allergy [1]. A larger head-to-head study published Sept. 7, 2026 in the Journal of Asthma and Allergy found no difference in flare-up risk between tirzepatide, sold as Mounjaro and Zepbound, and semaglutide, sold as Ozempic, Wegovy and Rybelsus [2].
The first report was a retrospective cohort study drawn from the TriNetX database, a network of health records from subscribing institutions [1]. It found asthma exacerbations in 3.0 percent of tirzepatide users compared with 3.8 percent of matched non-users, and among people who did have a flare-up, tirzepatide users had fewer events each [1]. The letter, a short research note rather than a full trial report, appeared in volume 56, issue 6 of the journal at pages 665–667 [1].
The second analysis compared the two drugs directly in adults who had both asthma and type 2 diabetes, using the TriNetX US Collaborative Network, which includes more than 65 health care organizations [2]. Researchers identified patients who started tirzepatide or semaglutide between June 2022 and December 2024 and followed them for up to 12 months; the study period ended Dec. 1, 2025 [2]. After matching patients one-to-one on baseline characteristics, each group contained 8,176 people [2]. Asthma exacerbation occurred in 11.0 percent of the tirzepatide group and 11.1 percent of the semaglutide group over 12 months (hazard ratio 1.00; 95 percent confidence interval, 0.91–1.10) [2]. The result held across sensitivity and subgroup analyses [2]. As secondary findings, tirzepatide was linked to slightly less use of short-acting beta-agonists (hazard ratio 0.92; 95 percent CI, 0.88–0.96) and a similar risk of systemic corticosteroid use (hazard ratio 1.01; 95 percent CI, 0.96–1.05) [2].
The two results are not directly comparable. The first study compared tirzepatide with people taking no such drug, not with semaglutide, so it does not show that tirzepatide's dual GIP and GLP-1 action adds a respiratory advantage over GLP-1 alone [1]. The second study tested exactly that question in a different population — patients with type 2 diabetes as well as asthma — and found no difference [2]. The authors of the second study wrote that the greater weight loss and blood sugar improvement seen with tirzepatide did not translate into a lower asthma exacerbation risk than semaglutide in their data [2].
Why it matters for patients
Asthma and type 2 diabetes often occur together, and people with both conditions tend to have poorer asthma control, more frequent and severe exacerbations, and higher use of health care than people with asthma alone [2]. Obesity adds to the problem by promoting airway hyperresponsiveness, changing lung mechanics and contributing to steroid resistance [2]. That has made it reasonable to ask whether GLP-1-based drugs help breathing as well as weight and blood sugar.
Neither study was a randomized controlled trial. Both used electronic health records, which can show associations but cannot prove that a drug caused the difference in flare-ups [1][2]. One is a brief research letter [1]; the other is a retrospective cohort analysis [2]. Neither report says whether these medications can replace or reduce inhaled asthma treatments or steroid courses, and neither changes the approved uses of tirzepatide or semaglutide.
What happens next
The authors of the head-to-head study concluded that randomized controlled trials are needed to clarify whether GLP-1-based therapies have a role in patients with asthma and type 2 diabetes [2]. No such trial, and no timeline for one, has been reported in either publication. The number of exacerbation events per affected patient in the first study, and the raw counts behind the 11.0 percent and 11.1 percent figures in the second, have not been disclosed in the materials described here [1][2].
Sources
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