GLP-1 medications like semaglutide and tirzepatide are great at helping people shed pounds. Unfortunately, these drugs might also help some people shed their hair, too, as new research suggests.
Scientists at the University of Pennsylvania examined medical records from people taking GLP-1s for their type 2 diabetes. People had a higher likelihood of hair loss after starting a GLP-1 than those taking other diabetes drugs, they found. Though the risk of losing hair appears to be small and likely reversible in many cases, people on GLP-1s and their doctors should be aware of the potential side effect, the researchers say.
“These findings also highlight the need for ongoing surveillance of dermatological adverse events in GLP-1 receptor agonist users,” they wrote in their paper, published Wednesday in The BMJ.
Losing weight and hair
There have been reports of alopecia, a.k.a. hair loss, linked to GLP-1 use. And following an FDA investigation of post-market data, GLP-1 drugs like Ozempic (semaglutide) and Zepbound (tirzepatide) are now required to list alopecia as a potential adverse reaction on their product labeling.
According to the researchers, however, there’s been relatively little research looking into this risk, particularly from large, population-based studies. So they decided to analyze data from people receiving care within the University of Pennsylvania Health System, or Penn Medicine.
All told, they looked at roughly 12,000 people with type 2 diabetes who were newly prescribed a GLP-1 between 2019 and 2024. They compared these patients to similarly sized groups of people who were instead taking SGLT-2 inhibitors or DPP-4 inhibitors, two other common classes of diabetes medication. The average follow-up period for each group was between two and three years.
After adjusting for factors like age and sex, GLP-1 users had a noticeably higher risk of later alopecia than either group of diabetes patients, the researchers found. People on GLP-1s were 37% more likely to develop alopecia than SGLT-2 users and 68% more likely than DPP-4 users.
The good news
Retrospective, observational studies like this one aren’t able to prove a cause-and-effect link between starting a GLP-1 and hair loss—they only show a correlation. But even if there is a genuine added risk from these drugs, it’s likely to be very small. For some context, only about 200 out of 12,000 GLP-1 users developed alopecia during the study period (roughly 1.6%).
After further analysis, the researchers also found this heightened risk was primarily associated with non-scarring alopecia, a type of hair loss where the follicles remain intact. That’s important since many people with this kind of alopecia do eventually regrow their hair back.
As for why GLP-1s might cause hair loss, the most likely explanation is the rapid or substantial weight loss that people can experience while on them, according to the authors. Such weight loss is already known to trigger a particular type of temporary hair loss called telogen effluvium. People’s reduced calories on these drugs might also lead them to become deficient in nutrients important to healthy hair growth like zinc and iron. That said, the researchers don’t rule out other possible factors, such as hormonal or immune changes caused by GLP-1 use.
More studies should be done to untangle those underlying mechanisms and to more clearly understand the severity and reversibility of GLP-1-induced hair loss, the researchers say. In the meantime, simply knowing about this risk, tiny as it probably is, can help people and their doctors navigate the use of these drugs.
“Although the absolute risk was small, awareness of this potential effect may support informed, patient-centered treatment decisions,” the researchers wrote.
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