Effects of <scp>GLP</scp> ‐1 Receptor Agonists on Hair Loss and Regrowth: A Systematic Review

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are increasingly used for metabolic disorders, including type 2 diabetes mellitus (T2DM) and obesity. Reports to date have documented hair loss as an adverse event, while cases of hair regrowth have also been described [1]. This review evaluates evidence linking GLP-1RA use to hair outcomes. Following PRISMA guidelines, Embase and MEDLINE were searched (from inception to July 2025) using keywords specific to GLP-1RAs, “alopecia,” and “hair regrowth” (PROSPERO: CRD420251104356). Of 485 records identified, 10 full-text studies were included, comprising three retrospective cohort studies, four retrospective pharmacovigilance database studies, one living benefit-harm modeling study, one case–control study, and one case report. Risk of bias was assessed using Joanna Briggs critical appraisal tools. Hair loss type was mostly unspecified; however, 82 patients had centrifugal cicatricial alopecia (CCCA), 20 had androgenic alopecia (AGA), and 10 had telogen effluvium. Pharmacovigilance and modeling analyses examined a total of 920,890 adverse events, while cohort studies involved 382 patients. GLP-1RAs investigated included exenatide (27.1%, 170,880/630,671), dulaglutide (23.4%, 147,624/630,671), liraglutide (21.4%, 135,178/630,671), semaglutide (11.3%, 71,528/630,671), and tirzepatide (9.9%, 62,196/630,671). Of 626,894 patients on GLP-1RA for whom hair outcomes were reported, 9933 (1.6%) experienced hair loss, whereas 52 (0.008%) reported hair regrowth. Latency to hair loss or gender differences in alopecia events were not well described in studies. Clinical outcomes are summarized in Table 1. Multiple pharmacovigilance analysis studies identified a weak association between GLP-1RA use and hair loss, most commonly with semaglutide (reporting odds ratio (ROR), 1.24–2.46), followed by tirzepatide (ROR, 0.83–1.73) and liraglutide (ROR, 0.61–1.53). One disproportionality analysis of the US Food and Drug Administration's Adverse Event Reporting System (FAERS) (2022–2023 exclusively) revealed a positive signal for alopecia with semaglutide (ROR, 2.46) and tirzepatide (ROR, 1.73), suggesting that rates may exceed background reporting levels [2]. A review of several pharmacovigilance databases (FAERS, Vigibase, Eudravigilance, Database of Adverse Event Notifications (DAEN)) found that GLP-1RAs were associated with greater reporting of hair loss compared with other antidiabetic medications; however, disproportionality analyses were negative [3]. Hair regrowth was observed in select cases, and was variably defined as improvement in density, symptom resolution, or hair loss stabilization. A 57-year-old male with insulin resistance, obesity, and AGA experienced hair regrowth and normalized insulin resistance parameters within 6 months of initiating tirzepatide [1]. In 81 patients with CCCA, longer GLP-1RA duration and improved metabolic parameters (e.g., reduced HbA1c) were associated with scalp symptom improvement and/or hair regrowth in 58.0% of patients classified as “GLP-1RA responders”; however, explicit hair regrowth data were not reported; therefore, the number experiencing true hair gains is unknown [4]. Conversely, a cohort study of 283 GLP-1RA users visiting a hospital-based dermatology clinic for any dermatologic diagnosis found mixed outcomes: 32 patients (11.3%) had new-onset or worsening hair loss, while three patients (1.1%) with preexisting hair loss had resolution/stabilization following treatment [5]. Several mechanisms may contribute to the relationship between GLP-1RA use and hair loss or regrowth (Figure 1). Hormonal changes (particularly involving insulin and insulin-like growth factor), rapid weight loss, and the psychosocial stress of managing chronic disease may influence androgen production or the hair follicle cycle, precipitating AGA or telogen effluvium. Changes in dietary intake and potential nutritional deficiencies (i.e., vitamin D) secondary to altered satiety could potentially also contribute. Semaglutide and tirzepatide had the strongest associations with hair loss (ROR values > 1); however, without direct comparison, it is unclear whether their risk is greater than that of other GLP-1RAs. Several types of hair loss (e.g., CCCA, AGA) may improve with glycemic control. Causality cannot be inferred, and study limitations include the predominance of pharmacovigilance data, where reporting bias or differential GLP-1RA prescribing patterns may confound results. Further larger cohort studies are required to determine if certain hair loss disorders may benefit or worsen from GLP-1RA therapy. M.K.B., M.S.L., E.M. and T.K.-H. have no conflicts of interest to declare. J.D. has received honoraria from Pfizer and Vichy, has participated on advisory boards at Pfizer for payment, receives royalties from UpToDate, participates on the Board of Directors for the Scarring Alopecia Foundation, and is the active director of the Evidence Based Hair Fellowship Training Program. The data underlying this study are available in the article and in the supplemental material at https://data.mendeley.com/datasets/k7pydjb66f/1.

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