Ten-year FAERS review finds alopecia reporting signals for semaglutide and tirzepatide

A new pharmacovigilance study published in the Journal of Cosmetic Dermatology found that reports of hair loss linked to semaglutide and tirzepatide showed up more often than expected in the FDA's Adverse Event Reporting System (FAERS), a voluntary database of side-effect reports ^[1]. The researchers, led by Aditya K. Gupta, looked at FAERS data from the first quarter of 2016 through the third quarter of 2025 ^[1]. They searched for reports of alopecia and related hair-loss terms tied to seven GLP-1 receptor agonist drugs: albiglutide, dulaglutide, exenatide, liraglutide, lixisenatide, semaglutide, and tirzepatide ^[1].

Over that decade, the team found 1,941 hair-loss-related reports across 1,929 patient cases involving this drug class ^[1]. Semaglutide, sold as Ozempic, Wegovy, and Rybelsus, had the most reports of any drug in the study, with 697 total ^[1]. A statistical signal, meaning hair-loss reports showed up more than would be expected by chance, appeared for semaglutide in 2022, with a reporting odds ratio of 1.43 (95% confidence interval, 1.15 to 1.77), and again in 2024, with a ratio of 1.55 (95% confidence interval, 1.35 to 1.77) ^[1]. According to the study summary, tirzepatide, sold as Mounjaro and Zepbound, showed signals in 2024 and 2025 ^[1]. No such signal turned up for dulaglutide, liraglutide, lixisenatide, albiglutide, or exenatide ^[1].

The researchers also looked at what happened when patients stopped or restarted the suspected drug. Among semaglutide reports with available data, 25% showed the hair loss improved after the drug was stopped, a pattern called positive dechallenge, and 18% showed the hair loss came back after the drug was restarted, called positive rechallenge ^[1]. The authors describe these dechallenge and rechallenge figures as new to the published literature on this topic ^[1].

The FDA first flagged alopecia as a possible side effect of GLP-1 drugs in July 2023 ^[1]. The connection was also noted earlier, in the 2021 STEP 3 clinical trial of semaglutide led by Wadden and colleagues, which listed alopecia as an adverse event ^[1].

Why it matters for patients

This study cannot tell patients how common hair loss is among people taking semaglutide or tirzepatide, or whether the drugs actually cause it. FAERS is built from voluntary reports, not a controlled study, so it cannot estimate incidence and cannot rule out other explanations, such as rapid weight loss itself, which is a known trigger of temporary hair shedding, or other health conditions a person may have ^[1]. The authors state plainly that FAERS "cannot estimate incidence or adjust for confounders," meaning the signal is a statistical flag for further study, not proof of a direct drug effect ^[1].

Still, the finding adds to a body of evidence, including the earlier FDA safety flag and the 2021 clinical trial data, that hair loss has been reported by some patients using these medications ^[1]. The fact that the signal appeared for semaglutide and tirzepatide but not for older GLP-1 drugs like dulaglutide, liraglutide, and exenatide may be useful for researchers trying to understand why, though the study itself does not explain the difference ^[1].

What happens next

The study's authors say their findings "merit further monitoring of GLP-1-RAs for hair loss," suggesting more research is likely to follow, though no specific studies or dates are mentioned in this report ^[1]. Until then, whether semaglutide or tirzepatide directly causes hair loss, and how often, remains an open question that this kind of database review cannot answer on its own ^[1].