GLP-1 USERS HAD 37% HIGHER HAIR LOSS RISK, STUDY FOUND
A BMJ study linked GLP-1 hair loss to a 37% higher alopecia risk than SGLT-2 inhibitors in adults with type 2 diabetes.
The research was published on July 22, 2026. It used electronic health records from Penn Medicine, the University of Pennsylvania Health System, and was an observational target trial emulation.
The authors were clear that the absolute risk is small. “Although the absolute risk is low, awareness of this potential effect may help to inform treatment decisions,” they wrote in the abstract conclusion.
They also stressed that the findings do not prove the drugs caused hair loss.
What the study measured
The team looked at adults with type 2 diabetes who newly started a GLP-1 drug, an SGLT-2 inhibitor or a DPP-4 inhibitor between January 2019 and September 2024. The study asked whether starting a GLP-1 drug was tied to a new alopecia diagnosis.
The GLP-1 group covered exenatide, liraglutide, dulaglutide, semaglutide, lixisenatide and tirzepatide.
After weighting to adjust for measured differences between patients, the hazard ratio for alopecia was 1.37 for GLP-1 users versus SGLT-2 users. Against DPP-4 users, it was 1.68.
In plain terms, Penn Medicine described GLP-1 users as 37% more likely to have hair loss than SGLT-2 users and 68% more likely than DPP-4 users.
The adjusted incidence rates were 6.91 cases per 1,000 person-years for GLP-1 users, versus 5.04 for SGLT-2 users.
The association was concentrated in non-scarring alopecia, a type that leaves hair follicles intact and may allow regrowth. The study did not find a clear link to alopecia areata.
Diagnoses clustered in the first year after patients started treatment, peaking just before the 12-month mark.
What the study could not say
Alopecia was identified through diagnostic codes in health records, not scalp exams or patient-reported hair counts. The study did not assess how severe any case was, how long it lasted or whether it reversed.
The paper suggested that weight loss or reduced calorie intake could contribute to non-scarring hair shedding. It did not establish a mechanism or measure how much weight loss played a role.
The authors noted that residual confounding is still possible in an observational study. The patients were adults with type 2 diabetes treated in one health system, so the results do not automatically apply to people taking GLP-1 drugs only for weight loss.
The paper’s discussion said earlier postmarketing reports had raised a possible safety signal and that the FDA was evaluating it.
The study was funded in part by the US National Institutes of Health. The authors wrote that the funder had no role in the research or the decision to publish.
What happened next
The BMJ Group news release the day after publication framed the result as an association and said the absolute risk remained low.
Penn Medicine then published its own article on the findings on August 31, 2026. It restated the risk comparisons and did not add a new result.
The researchers said more studies are needed to clarify mechanisms, assess severity and reversibility, and identify people who may be at higher risk.
For now, the authors’ practical advice stands. “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 wrote.
