Hair loss with GLP-1 drugs is rare but real, studies find

The risk of hair loss in patients taking GLP-1 drugs for obesity or diabetes, while low, is higher than with other diabetes drugs, new studies suggest.

At two or more years after starting treatment, the odds of a new diagnosis of alopecia in GLP-1 users were 37% higher than in users of so-called SGLT-2 drugs and 68% higher versus DPP-4 drugs, researchers at the University of Pennsylvania reported on Wednesday, July 22, in The BMJ.

Actual rates of alopecia were low, ranging from roughly 3 to 9 per 1,000 people per year, with between 11,000 and 15,000 people in each drug-class group.

GLP-1 drugs in the study included semaglutide, sold by Novo Nordisk as Wegovy and Ozempic; tirzepatide, sold by Eli Lilly as Zepbound and Mounjaro; and older drugs in the class.

SGLT-2 drugs included Johnson & Johnson's Invokana, AstraZeneca's Farxiga, and Jardiance from Boehringer Ingelheim and Eli Lilly. DPP-4 inhibitors included Merck’s Januvia and AstraZeneca’s Onglyza.

A separate recent study in the Journal of the American Academy of Dermatology with more than 1 million participants worldwide found significantly higher risks of various subtypes of alopecia with GLP-1 drugs than with the commonly used diabetes drug metformin.

A third new study suggests GLP-1 users face higher alopecia odds with tirzepatide than with semaglutide.

Researchers at Cambridge, Massachusetts-based analytics firm nference compared 11,046 patients taking tirzepatide with the same number taking semaglutide. Rates of new-onset alopecia were 4.24% with tirzepatide and 3.33% with semaglutide, according to a preprint submitted for peer review.

In female users of GLP-1 drugs, those rates were 5.44% with tirzepatide versus 3.63% with semaglutide, the researchers said.

All three papers say that hair loss often accompanies weight loss and is often reversible.

But in the inference study, the risk was higher with tirzepatide regardless of how much weight patients lost or how much of the drug they received, which suggests that other explanations for hair loss may need to be considered, the researchers said.

For example, the study also showed that alopecia was more likely in patients with thyroid disease or other endocrine disorders, which could indicate a connection to baseline hormonal, autoimmune, or dermatologic risk factors, said Venky Soundararajan, who led the inference study.

“This supports more individualized counseling and surveillance rather than a generic message that weight loss itself inevitably causes hair loss,” he said.