GLP-1 Receptor Agonists Linked to Increased Hair Loss Risk in Type 2 Diabetes, Study Finds
Key Insights
Use of GLP-1 receptor agonists was associated with a 37% higher risk of alopecia (search) compared with SGLT-2 inhibitors and 68% higher risk versus DPP-4 inhibitors in adults with type 2 diabetes (search).
Absolute rates of alopecia (search) remained low, ranging from roughly 3 to 9 per 1,000 person-years across all drug-class groups in the University of Pennsylvania study published in The BMJ.
A separate nference (search) preprint found higher alopecia (search) rates with tirzepatide (4.24%) compared with semaglutide (3.33%), with the difference persisting regardless of weight loss magnitude.
Use of glucagon-like peptide-1 (GLP-1) receptor agonists — widely prescribed for type 2 diabetes (search) and obesity — is associated with an increased risk of hair loss (alopecia (search)) in adults with type 2 diabetes, according to a study published by The BMJ. While the absolute risk remains low, the findings provide the most systematic evidence to date linking this popular drug class to alopecia and may help inform shared treatment decisions between clinicians and patients.
The study, conducted by researchers at the University of Pennsylvania Health System (Penn Medicine), analyzed electronic patient data from 12,004 GLP-1 receptor agonist users compared with 15,221 users of SGLT-2 inhibitors, and a further 11,964 GLP-1 users compared with 11,233 DPP-4 inhibitor users, covering the period from January 2019 to September 2024.
Significantly elevated risk across comparator groups
After adjusting for potentially influential factors including age, sex, ethnicity, pre-existing conditions, other medication use, and body mass index, GLP-1 receptor agonist use was associated with a 37% higher risk of alopecia (search) compared with SGLT-2 inhibitors (6.91 vs. 5.04 per 1,000 person-years) and a 68% higher risk compared with DPP-4 inhibitors (6.53 vs. 3.89 per 1,000 person-years).
Further analyses indicated the association was specific to non-scarring alopecia (search) — where hair follicles remain intact, leaving the potential for regrowth — with an increased risk of 53% and 72% compared with SGLT-2 inhibitors and DPP-4 inhibitors, respectively.
The GLP-1 receptor agonist users in the study were younger (mean age 58 vs. 65 for SGLT-2 inhibitor users and 58 vs. 67 for DPP-4 inhibitor users) and had a higher body mass index (36.2 vs. 32.3 and 36.2 vs. 31.3, respectively), with lower rates of cardiovascular and chronic kidney diseases.
Potential mechanisms under investigation
The authors note that rapid weight loss is a well-established trigger of hair shedding and can lead to iron or zinc deficiencies, which disrupt the hair growth cycle. Hormonal changes may also be relevant, although the researchers emphasize that further studies are needed to clarify the underlying mechanisms.
The study acknowledges several limitations, including a lack of clinical information that limited the ability to assess details such as severity, extent, duration, and reversibility of alopecia (search) after stopping treatment. The possibility that other unmeasured factors may have influenced the results cannot be ruled out.
Nevertheless, the researchers describe the study as rigorous, based on high-quality data from a large representative cohort, with results that remained consistent after additional analyses. "Our findings extend previous anecdotal safety signals and provide more systematic evidence to inform clinical awareness of this potential adverse effect," they conclude.
Tirzepatide vs. semaglutide: differential risk emerges
A separate preprint study from Cambridge, Massachusetts-based analytics firm nference (search), submitted for peer review, compared 11,046 patients taking tirzepatide with an equal number taking semaglutide. Rates of new-onset alopecia (search) were 4.24% with tirzepatide and 3.33% with semaglutide. Among female users, those rates rose to 5.44% with tirzepatide versus 3.63% with semaglutide.
Notably, the risk was higher with tirzepatide regardless of how much weight patients lost or how much of the drug they received, suggesting that explanations for hair loss beyond weight reduction may need to be considered. The study also showed that alopecia (search) 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.
"This supports more individualized counseling and surveillance rather than a generic message that weight loss itself inevitably causes hair loss," said Venky Soundararajan, who led the nference (search) study.
A third recent study published in the Journal of the American Academy of Dermatology, encompassing more than 1 million participants worldwide, found significantly higher risks of various subtypes of alopecia (search) with GLP-1 drugs compared with the commonly used diabetes drug metformin. All three papers note that hair loss often accompanies weight loss and is frequently reversible.