Drugs that have reshaped treatment for type 2 diabetes and sparked a boom in medical weight loss—Mounjaro, Ozempic and Wegovy among them—may also carry a higher risk of hair loss, researchers report.
People taking GLP-1 agonist medications have been flagging hair loss to regulators for some time. Now, a study involving roughly 50,000 people adds more weight to those reports by comparing real-world rates of alopecia among patients using GLP-1 drugs with those taking other diabetes treatments.
Using electronic patient records from the University of Pennsylvania Health System, researchers examined adults prescribed GLP-1 receptor agonists for diabetes management and measured how often they were diagnosed with alopecia versus patients treated with other drug classes.
The team also pointed to existing safety signals reported to regulators in the US, noting that concerns about hair loss have been raised most often for semaglutide—sold as Wegovy and Ozempic—and tirzepatide, marketed as Mounjaro.
In the UK, the Medicines and Healthcare products Regulatory Agency has logged 399 reports of hair loss associated with tirzepatide so far in 2026, following 541 reports last year.
For semaglutide, the regulator has received 148 hair-loss reports in 2026 to date, after 164 reports last year.
For the new analysis, the researchers compared people with type 2 diabetes taking GLP-1 receptor agonists with those using two other common diabetes drug categories: SGLT-2 inhibitors and DPP-4 inhibitors.
In total, 12,004 patients using GLP-1s were compared with 15,221 using SGLT-2 inhibitors, and a further 11,964 GLP-1 users were compared with 11,233 DPP-4 inhibitor users.
After adjusting for factors that can affect outcomes—such as age and weight—the study found that GLP-1 use was associated with a 37% higher risk of alopecia compared with SGLT-2 inhibitors.
When GLP-1s were measured against DPP-4 inhibitors, researchers reported a 68% higher risk of hair loss among GLP-1 users.
A deeper look at the data suggested the association was tied to non-scarring alopecia, meaning hair follicles remain intact and regrowth may still be possible.
Writing in the British Medical Journal, the researchers—including authors from the University of Pennsylvania—said: “Case reports and analyses of the US Food and Drug Administration’s Adverse Event Reporting System have described occurrences of hair loss following initiation of a GLP-1 receptor agonist, particularly semaglutide and tirzepatide.
“In response, the FDA has indicated that it is evaluating this potential safety signal.
“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.”
As for why hair loss may occur, the researchers said the “most likely mechanism” is linked to weight loss itself and “reduced caloric intake,” while emphasizing that more research is needed.
They said cutting calories may “contribute to physiological stress and micronutrient deficiencies (for example, iron, zinc, biotin), which can disrupt the hair growth cycle”.
The paper also pointed to other possible contributors, including the “metabolic, hormonal, and immunological effects attributed to GLP-1 receptor agonists that may influence hair follicle growth and cycling”.
For instance, the team noted that GLP-1 receptor agonists have been tied to changes in thyroid function, and that delayed gastric emptying could affect absorption of oral medications, including thyroid hormone or sex hormone therapies.
“Such changes could influence hair growth through endocrine mechanisms, particularly in individuals with underlying hormonal conditions.”
The researchers concluded: “Our findings extend previous anecdotal safety signals and provide more systematic evidence to inform clinical awareness of this potential adverse effect.”
