GLP-1 therapies and hair loss: A systematic review of current evidence and implications for counseling.

ObjectiveTo evaluate glucagon-like peptide-1 receptor agonist (GLP-1 RA)-specific associations with hair loss, characterize reported alopecia subtypes and discuss potential underlying mechanisms.MethodsA systematic literature search was conducted across four databases (PubMed, Embase, Scopus, and Web of Science) according to PRISMA guidelines and registered in PROSPERO (CRD420261297384). Studies were included if they were primary articles assessing hair loss related to GLP-1 RA use.ResultsOf 133 studies identified, 24 met inclusion criteria. Among GLP-1 RAs, semaglutide and tirzepatide demonstrated the highest incidence rates of hair loss and more frequent signal detection in pharmacovigilance studies. Although infrequently classified overall, androgenetic alopecia and telogen effluvium were the predominant subtypes of hair loss reported. Tirzepatide, associated with the greatest magnitude of weight loss, was most frequently linked to telogen effluvium. Hair loss associated with semaglutide appeared to be dose-dependent, with doses < 2mg weekly rarely implicated while higher obesity-treatment doses were more commonly associated with hair loss. Females appeared to be disproportionately affected. Rapid weight loss emerged as a potential contributor, particularly for telogen effluvium. In contrast, fewer studies assessed hair loss with liraglutide, dulaglutide, lixisenatide and exenatide, and they typically exhibited lower reported risk when compared to semaglutide and tirzepatide.ConclusionsAccumulating evidence from pharmacovigilance databases and clinical cohorts suggests an increased risk of hair loss with certain GLP-1 RAs, particularly semaglutide and tirzepatide. Further studies are needed to clarify the etiology of drug-induced weight loss, identify vulnerable populations, and establish causality and temporal relationship through large, prospective randomized trials.