Scientists have found that the chances of hair loss in patients taking GLP-1 drugs for obesity or diabetes, while low, are higher than with other diabetes drugs, with three separate studies confirming similar findings, reports Reuters.
Two of the studies suggested that new diagnoses of alopecia are more common with GLP-1 drugs than with other diabetes drugs, although rare overall, while the third found that new-onset alopecia was more common with tirzepatide than with semaglutide
But weight loss alone likely doesn’t explain patients’ hair loss, the researchers said.
According to the findings of the study team at the University of Pennsylvania, published last week in The BMJ, 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.
Actual rates of alopecia were low, ranging from roughly three to nine 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 1m 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 nference 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 nference study.
“This supports more individualised counselling and surveillance rather than a generic message that weight loss itself inevitably causes hair loss,” he said.
Study details
Risk of hair loss associated with glucagon-like peptide-1 receptor agonists in adults with type 2 diabetes: target trial emulation
Huilin Tang, Bingyu Zhang, Yiwen Lu et al.
Published in The BMJ on 23 June 2026
Abstract
Objective
To examine the association between glucagon-like peptide-1 (GLP-1) receptor agonists and the risk of incident alopecia (hair loss) in adults with type 2 diabetes, compared with sodium-glucose cotransporter-2 (SGLT-2) inhibitors and dipeptidyl peptidase-4 (DPP-4) inhibitors.
Design
Target trial emulation.
Setting
Electronic health records from Penn Medicine.
Participants
Adults (>18 years) with type 2 diabetes.
Exposures
New initiation of GLP-1 receptor agonists, SGLT-2 inhibitors, or DPP-4 inhibitors between January 2019 and September 2024.
Main outcome measures
Outcomes of interest included incident alopecia and its subtypes, identified by using diagnostic codes. Stabilised inverse probability of treatment weighting was applied to balance baseline covariates between treatment groups, and Cox proportional hazards models were used to estimate hazard ratios with 95% confidence intervals. Multiple sensitivity (including negative control outcome calibration) and subgroup analyses were done to assess robustness.
Results
This study included 12 004 GLP-1 receptor agonist initiators and 15 221 SGLT-2 inhibitor initiators in the GLP-1 receptor agonist versus SGLT-2 inhibitor comparison and 11 964 GLP-1 receptor agonist initiators and 11 238 DPP-4 inhibitor initiators in the GLP-1 receptor agonist versus DPP-4 inhibitor comparison. After stabilised inverse probability of treatment weighting adjustment, use of GLP-1 receptor agonists was associated with a higher risk of alopecia than use of SGLT-2 inhibitors (hazard ratio 1.37, 95% confidence interval 1.08 to 1.73) or DPP-4 inhibitors (1.68, 1.28 to 2.20). The associations were consistent across sensitivity and subgroup analyses, with attenuation after negative control outcome calibration. Subtype analyses indicated that the association was specific to non-scarring alopecia, with hazard ratios of 1.53 (1.18 to 1.97) and 1.72 (1.28 to 2.31) compared with SGLT-2 inhibitors and DPP-4 inhibitors, respectively.
Conclusions
Use of GLP-1 receptor agonists was associated with an increased risk of non-scarring alopecia in adults with type 2 diabetes. Although the absolute risk is low, awareness of this potential effect may help to inform treatment decisions.
Reuters article – Hair loss with GLP-1 drugs is rare, but real, studies find (Open access)
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