Claims study reports increased hair loss risk with semaglutide in women

A preprint posted March 6, 2025 on medRxiv reports that women prescribed semaglutide for weight loss had a higher risk of hair loss than women taking bupropion-naltrexone, another weight-loss drug ^[1]. The paper has not yet been peer-reviewed, meaning it has not gone through the usual outside expert review that checks a study's methods and conclusions before publication ^[1].

The research team, based at the University of British Columbia, is the same group that published an earlier 2023 study on gastrointestinal side effects of GLP-1 drugs ^[1]. For this new analysis, they used a health claims database and pulled a random sample of 16 million patients, then narrowed the group to new users of semaglutide or bupropion-naltrexone who did not have diabetes or prior use of diabetes medications ^[1]. The final study group included 1,926 semaglutide users and 1,348 bupropion-naltrexone users ^[1].

After adjusting for factors including age, sex, location, depression, steroid use, hypothyroidism, polycystic ovary syndrome, and anemia, the researchers calculated an adjusted hazard ratio for hair loss of 1.52 for all semaglutide users compared with the bupropion-naltrexone group ^[1]. That overall figure had a wide confidence interval, from 0.86 to 2.69, meaning the result was not statistically significant for the group as a whole ^[1]. When the researchers split the results by sex, the hazard ratio for men was 0.86, also not statistically significant, with a very wide range of 0.05 to 14.49 ^[1]. For women, the hazard ratio was 2.08, with a confidence interval of 1.17 to 3.72, which the authors describe as showing a statistically significant increased risk of hair loss in women taking semaglutide ^[1].

The study's lead author disclosed having previously consulted on Ozempic litigation, a legal proceeding related to the drug ^[1]. The study was funded through internal research funds from the University of British Columbia's Department of Ophthalmology and Visual Sciences ^[1]. The authors state that future studies are needed to confirm any association between semaglutide and hair loss ^[1].

Why it matters for patients

Hair loss has already been listed as a possible side effect for semaglutide products, but this preprint attempts to measure how much more common it might be compared with another weight-loss medication, rather than compared with no treatment at all ^[1]. The finding that women may face a higher risk than men, if confirmed, could be useful information for people weighing treatment options. However, because this is a preprint and not a peer-reviewed publication, outside experts have not yet formally evaluated the study's methods, data quality, or conclusions ^[1]. The authors themselves state their paper