Hair loss is an emerging and clinically significant adverse effect associated with glucagon-like peptide-1 receptor agonist (GLP-1 RA) therapy, occurring in approximately 3%-5% of treated patients across pivotal clinical trials, with a pooled risk ratio of approximately 3.3 compared with placebo. The predominant mechanism is telogen effluvium (TE) secondary to rapid weight loss and caloric restriction, though direct effects on the hair follicle via GLP-1 receptor expression in dermal white adipose tissue (dWAT), hormonal shifts, and nutritional insufficiency also contribute. Pharmacovigilance data from the United States Food and Drug Administration Adverse Event Reporting System (FAERS) and large real-world cohort studies further support a clinically meaningful signal. This chapter reviews the epidemiology and agent-specific differences in GLP-1 RA-associated alopecia, the pathophysiologic mechanisms, potential beneficial effects on androgenetic alopecia (AGA) and cicatricial conditions, and a systematic approach to clinical evaluation and management. Management strategies include nutritional optimization with protein targets of 1.2-2.0 g/kg/day based on adjusted body weight, patient counseling on the anticipated time course of hair shedding, and pharmacologic options including low-dose oral minoxidil. The hair loss profile of GLP-1 RAs is compared with that of bariatric surgery, where pooled incidence ranges from 47%-57%. Practical guidance for the clinician is provided throughout.
GLP-1 Therapies