Researchers put the added odds at 37 to 68%, though absolute risk stays low
The GLP-1 medications now widely prescribed for diabetes and obesity carry a small but measurable added risk of hair loss compared with older glucose-lowering drugs.
University of Pennsylvania researchers reported in The BMJ on Wednesday that patients who started a GLP-1 drug had 37 percent higher odds of a new alopecia diagnosis than those on SGLT-2 inhibitors, and 68 percent higher odds than those taking DPP-4 inhibitors.
The absolute risk stayed low.
According to the study, new alopecia diagnoses ran at roughly three to nine cases per 1,000 people each year across drug groups of between 11,000 and 15,000 patients, all of them adults with type 2 diabetes.
The analysis drew on Penn Medicine electronic health records covering January 2019 to September 2024, with follow-up averaging about two and a half years.
The signal was concentrated in non-scarring alopecia, the researchers said, the reversible shedding often tied to rapid weight loss.
Compared with SGLT-2 users, GLP-1 patients had 53 percent higher odds of that subtype; against DPP-4 users the figure was 72 percent.
The GLP-1 class in the Penn study included semaglutide, sold by Novo Nordisk as Ozempic and Wegovy, and tirzepatide, marketed by Eli Lilly as Mounjaro and Zepbound, alongside older drugs.
The comparator groups covered SGLT-2 inhibitors such as AstraZeneca's Farxiga and Boehringer Ingelheim and Eli Lilly's Jardiance, and DPP-4 inhibitors including Merck's Januvia, Reuters reported.
Two further studies pointed the same way.
A separate analysis in the Journal of the American Academy of Dermatology, with more than 1m participants worldwide, found significantly higher risks of several alopecia subtypes among GLP-1 users than among people taking metformin, as per Reuters.
A third study suggested the risk differs within the GLP-1 class itself.
Researchers at the analytics firm nference, based in Cambridge, Massachusetts, compared 11,046 patients on tirzepatide with an equal number on semaglutide.
New-onset alopecia reached 4.24 percent with tirzepatide and 3.33 percent with semaglutide, the researchers said in a preprint submitted for peer review.
Among women, the gap widened to 5.44 percent versus 3.63 percent.
That difference held regardless of how much weight patients lost or how much of the drug they took, according to nference, which the team said points to explanations beyond weight loss alone.
The study also found alopecia more common in patients with thyroid disease or other endocrine disorders, a possible link to baseline hormonal, autoimmune, or dermatological risk, said Venky Soundararajan, who led the work.
"This supports more individualized counseling and surveillance rather than a generic message that weight loss itself inevitably causes hair loss," Soundararajan said.
All three papers noted that hair loss frequently accompanies weight loss and is often reversible.
The authors framed it as an outcome patients care about, one that even in routinely recorded cases could shape whether someone starts or stays on treatment, making it relevant to shared decision making.
