# Respiratory Side Effects of Weight-Loss Drugs: A Review of 123 Studies | This GLP A systematic review and meta-analysis of 123 studies found no increase in respiratory adverse events on weight-loss drugs | 122 were in general populations and one in people with asthma. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/one-asthma-study-in-a-hundred-and-twenty-three Updated: 2026-09-18 Published: 2026-09-17 [← Research](https://thisglp.com/research) Safety # Respiratory Side Effects of Weight-Loss Drugs: A Review of 123 Studies A meta-analysis of 123 studies found no excess respiratory adverse events on weight-loss drugs. One of those studies was conducted in people with asthma. [This GLP Editorial Team](https://thisglp.com/about)September 20266 min readUpdated September 2026 123 studies included · One study was conducted in people with asthma. · The review exists because obesity and asthma coexist. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - A systematic review screened 9,086 records and included 123 studies of respiratory adverse events on weight-loss drugs. - Liraglutide, semaglutide, tirzepatide and naltrexone-bupropion showed no increase in respiratory adverse events against placebo, with the randomized trials at low risk of bias. - Of the 123 studies, 122 were in general populations and one was specifically in people with asthma. - Data were insufficient to assess orlistat, phentermine-topiramate and setmelanotide, which means unmeasured rather than cleared. Obesity and asthma occur together often, each makes the other worse, and losing weight improves asthma outcomes. That is the stated reason this review was conducted, and the exacerbation evidence on the efficacy side is in [a ratio of 0.438, a difference of 2.2 points](https://thisglp.com/research/glp1-asthma-relative-and-absolute). The safety question is separate: do these drugs themselves cause breathing problems[\[1\]](https://thisglp.com/research/one-asthma-study-in-a-hundred-and-twenty-three#ref-1). The answer is no, as far as the data goes. Across 123 studies, liraglutide, semaglutide, tirzepatide and naltrexone-bupropion were not associated with increased respiratory adverse events compared with placebo, and the randomized trials contributing carried a low risk of bias. For a class taken by tens of millions of people, that is a useful null. One hundred and twenty-two of the studies were not about asthma Of the 123 included studies, 122 evaluated general populations and exactly one evaluated people with asthma — in a review whose entire premise is that obesity and asthma coexist and compound each other. So the reassurance applies to people who mostly did not have the condition the question was asked about, and the specific worry — that a drug might worsen breathing in someone whose breathing is already compromised — is addressed by a single study. What counts as a respiratory adverse event in a weight-loss trial is worth knowing too. These are dominated by upper respiratory tract infections, which is to say colds. A null result on that measure says these drugs do not make people catch more colds. It is a weaker statement than “these drugs do not affect the lungs”, and the two will be reported as the same thing. Three drugs could not be assessed at all. Insufficient data limited comparisons for orlistat, phentermine-topiramate and setmelanotide, which means they are unmeasured rather than cleared — a distinction that matters given phentermine-topiramate’s position in [the network meta-analysis of nineteen drugs](https://thisglp.com/research/the-best-losers-are-the-worst-tolerated), where it ranked among both the more effective and the less tolerated. For anyone with asthma weighing one of these drugs, the practical position is that nothing suggests harm and almost nothing has been measured in people like them. That is a common shape in this literature, and it recurs in [the COPD flare-up comparisons](https://thisglp.com/research/do-glp1-drugs-help-copd) and [the analysis in older adults](https://thisglp.com/research/are-glp1-drugs-safe-for-older-adults), where the population studied and the population asking are not the same people. ## Frequently asked Do these drugs cause breathing problems? No increase in respiratory adverse events appeared for liraglutide, semaglutide, tirzepatide or naltrexone-bupropion across 123 studies, with the randomized trials at low risk of bias. Does that reassurance cover people with asthma? Barely. Of the 123 included studies, 122 evaluated general populations and one evaluated people with asthma specifically. What about other weight-loss drugs? Orlistat, phentermine-topiramate and setmelanotide could not be assessed because the data were insufficient, which means unmeasured rather than shown to be safe. ## Sources 1. \[1\] Zeng L, Zinmon-Htet C, Hundie T, Lin S, et al. (2026). Respiratory Adverse Events of Weight-Loss Drugs: A Systematic Review and Meta-Analysis Annals of the American Thoracic Society. [PMID 42479131](https://pubmed.ncbi.nlm.nih.gov/42479131/) ## More in Safety - [ Medication list · Check combinations · Fluid loss · Changes kidney risk · Pharmacist · Choose a safe option ### Can You Take Ibuprofen With Ozempic? 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