PHILADELPHIA — A study published in The BMJ found that GLP-1 receptor agonists are associated with a higher risk of alopecia compared to other diabetes medications. Yong Chen is a researcher at the University of Pennsylvania Perelman School of Medicine. The study was a target trial emulation using electronic health record data from Penn Medicine spanning January 2019 through September 2024. The average follow-up period for the study was 2.7 years.

The research compared 12,004 adults initiating GLP-1 receptor agonists with 15,221 initiating SGLT-2 inhibitors. A separate comparison group included 11,964 adults initiating GLP-1 receptor agonists and 11,238 initiating DPP-4 inhibitors. In the study cohort, GLP-1 users had a mean age of 58 compared to 65 for SGLT-2 inhibitor users.

GLP-1 users had a mean body mass index of 36.2 compared to 32.3 for SGLT-2 inhibitor users. In the comparison with DPP-4 inhibitors, GLP-1 users had a mean age of 58 compared to 67 for the other group. The mean body mass index for GLP-1 users was 36.2 compared to 31.3 for DPP-4 inhibitor users. GLP-1 users had lower rates of cardiovascular and chronic kidney diseases compared to SGLT-2 inhibitor users.

GLP-1 receptor agonist use was associated with a 37% higher risk of alopecia compared to SGLT-2 inhibitor use (HR 1.37, 95% CI 1.08-1.73). The incidence rate of alopecia was 6.91 per 1,000 person-years for GLP-1 users versus 5.04 per 1,000 person-years for SGLT-2 inhibitor users. Compared to DPP-4 inhibitor use, GLP-1 receptor agonist use was associated with a 68% higher risk of alopecia (HR 1.68, 95% CI 1.28-2.20). The incidence rate for this comparison was 6.53 per 1,000 person-years for GLP-1 users versus 3.89 per 1,000 person-years for DPP-4 inhibitor users.

Patients initiating GLP-1 drugs had a 53% higher risk of non-scarring alopecia compared to those taking SGLT-2 inhibitors. GLP-1 use was associated with a nearly fourfold increased risk of cicatricial alopecia compared to DPP-4 inhibitor use (HR 3.83, 95% CI 1.55–9.46). GLP-1 use was not associated with a significantly increased risk of cicatricial alopecia compared to SGLT-2 inhibitors (HR 1.10, 95% CI 0.56–2.16).

The study authors acknowledged that the analysis relied on diagnostic codes, so milder or unrecorded instances of hair thinning were likely missed. Chen addressed the clinical implications of the findings in the study. "Although the absolute risk of clinically recorded alopecia associated with GLP-1 receptor agonist use is low, the observed association may still influence patients' satisfaction, adherence, and decisions to start or continue therapy," he said. "Hair loss is a patient-valued outcome, and even cases captured in routine clinical care may be important for shared decision-making."

He outlined potential mechanisms for the observed hair loss. "Rapid or substantial weight loss is a well-established trigger of telogen effluvium, a form of diffuse, non-scarring hair shedding," he said. "Caloric restriction may also contribute to physiological stress and micronutrient deficiencies (for example, iron, zinc, biotin), which can disrupt the hair growth cycle." He offered guidance for medical practitioners managing patients on these medications.

"Clinicians may consider discussing the possibility of hair loss when initiating GLP-1 receptor agonist therapy and monitoring for symptoms during follow-up, particularly in the first year," he said. "Supportive measures such as ensuring adequate nutrition, reviewing concurrent factors that may contribute to hair loss, and referral to dermatology when appropriate may be needed." He concluded with recommendations for future research directions. "Future studies incorporating patient-reported outcomes and more detailed clinical assessments may help to better characterize the frequency, severity, and reversibility of alopecia, and to inform strategies to minimize its impact while preserving the metabolic benefits of treatment of GLP-1 receptor agonists," he said.

He described the broader impact of the condition on patients. Although hair loss does not typically result in physical harm, it may have significant psychosocial consequences, affecting self-esteem, quality of life, and adherence to treatment, he said. Other research has examined similar associations in larger populations.

A preprint study of 16 million patients found that women who initiated semaglutide treatment had double the risk of hair loss compared to those starting bupropion-naltrexone. A study using the TriNetX database showed that patients on GLP-1 agonists had higher rates of non-scarring hair loss, telogen effluvium, and androgenetic alopecia compared with a matched group not on the drugs.

The study provides quantitative evidence linking GLP-1 receptor agonists to hair loss in adults with type 2 diabetes, a population that increasingly relies on these medications for weight management and glycemic control. The findings suggest that clinicians should monitor for alopecia during the first year of treatment and consider nutritional support to mitigate potential side effects. As GLP-1 drugs continue to gain popularity, understanding the full spectrum of their effects, including psychosocial impacts, becomes essential for informed shared decision-making between providers and patients.