New study links GLP-1s to hair loss

Adults with type 2 diabetes who used a GLP-1 receptor agonist had an increased risk of clinically recorded hair loss, data from a target trial emulation suggested.

Compared with other antidiabetic medications, GLP-1 drug use was associated with a higher overall risk of alopecia over an average follow-up of 2.7 years, after adjusting for baseline differences:

• Versus SGLT-2 inhibitors: HR 1.37, 95% CI 1.08-1.73
• Versus DPP-4 inhibitors: HR 1.68, 95% CI 1.28-2.20

Associations were consistent across subgroup and sensitivity analyses, reported Yong Chen, PhD, of the University of Pennsylvania Perelman School of Medicine in Philadelphia, and colleagues in The BMJ.

"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," Chen and co-authors wrote.

"Hair loss is a patient-valued outcome, and even cases captured in routine clinical care may be important for shared decision-making," they continued. "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."

Elevated risk was driven primarily by non-scarring alopecia, the researchers said. Patients initiating GLP-1 drugs had 53% and 72% higher risks compared with those taking SGLT-2 inhibitors and DPP-4 inhibitors, respectively.

Non-scarring alopecia is the most common subtype of hair loss, frequently triggered by rapid weight loss and calorie restriction and typically reversible. Recognizing this distinction can help clinicians reassure patients, Chen and his team pointed out.

"Rapid or substantial weight loss is a well-established trigger of telogen effluvium, a form of diffuse, non-scarring hair shedding," they explained. "Caloric restriction may also contribute to physiological stress and micronutrient deficiencies (for example, iron, zinc, biotin), which can disrupt the hair growth cycle. This ... suggests that hair loss may reflect downstream effects of metabolic change rather than a direct drug effect."

GLP-1 use also was associated with a nearly fourfold increased risk of cicatricial alopecia (scarring hair loss) compared with DPP-4 inhibitor use (HR 3.83, 95% CI 1.55–9.46), but not compared with SGLT-2 inhibitors (HR 1.10, 95% CI 0.56–2.16).

Proactive communication with patients is essential, Chen and co-authors said. "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," they suggested. "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."

The findings add to growing evidence linking popular weight-loss and diabetes medications with hair loss, dating back to clinical trials for semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound).

Last year, 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 the weight-loss combination bupropion-naltrexone (Contrave). And another study using the TriNetX database showed that patients on GLP-1 agonists had significantly higher rates of non-scarring hair loss overall -- and telogen effluvium and androgenetic alopecia specifically -- compared with a matched group of individuals not on the drugs.

Individual case reports and data from the FDA's Adverse Event Reporting System have also flagged hair loss after patients started using GLP-1 drugs.

In this emulated trial, Chen and colleagues extracted electronic health record data from Penn Medicine spanning January 2019 through September 2024. They identified adults with type 2 diabetes who were newly prescribed GLP-1 receptor agonists, SGLT-2 inhibitors, or DPP-4 inhibitors.

The final cohorts included 12,004 GLP-1 drug initiators versus 15,221 SGLT-2 inhibitor initiators, and 11,964 GLP-1 drug initiators versus 11,238 DPP-4 inhibitor initiators.

Alopecia incidence rates were low: 6.91 versus 5.04 per 1,000 person-years for the GLP-1 drug versus SGLT-2 inhibitor cohort, and 6.53 versus 3.89 for the GLP-1 drug versus DPP-4 inhibitor cohort.

Because the analysis relied on diagnostic codes to identify alopecia cases, milder, transient, or unrecorded instances of hair thinning were likely missed, Chen and co-authors acknowledged.

The researchers stressed a need for ongoing surveillance as GLP-1 drug use continues to grow. "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," they stated.