Ozempic and Mounjaro Linked to Modest Rise in Hair Loss Risk, BMJ Study Finds

Key Takeaways: 

• Adults living with type 2 diabetes taking GLP-1 receptor agonists developed alopecia more often than those taking SGLT-2 inhibitors (37% higher risk) or DPP-4 inhibitors (68% higher risk), a BMJ study reports.
  
• Absolute risk stayed low, at 6.91 cases per 1,000 person years for GLP-1 receptor agonists against 5.04 for SGLT-2 inhibitors and 3.89 for DPP-4 inhibitors.
  
• The association was confined to non-scarring alopecia, where the follicle stays intact and regrowth remains possible.
  
  
  

A modest signal, but one worth discussing in the consultation

Medications from the GLP-1 receptor agonist class, now widely used in the management of type 2 diabetes and obesity, may be associated with a modest increase in hair loss. The finding comes from a study published by The BMJ on 22 July 2026.

The class includes semaglutide, marketed under brand names such as Ozempic and Wegovy, and tirzepatide, marketed as Mounjaro and Zepbound. Researchers found that adults living with type 2 diabetes who were treated with GLP-1 receptor agonists went on to develop alopecia more frequently than people prescribed two other commonly used classes of diabetes medication.

Although the relative increase was significant, the researchers emphasised that the absolute risk of hair loss remained low. Even so, awareness of the possible adverse effect could help people and their clinicians reach better informed treatment decisions together.

Reports of hair loss with semaglutide and tirzepatide

Hair loss has been reported before as a possible adverse effect of GLP-1 receptor agonists, particularly with medications containing semaglutide or tirzepatide. What has been missing is research that directly compares the risk among people taking these medicines with the risk among people taking alternative diabetes treatments.

To address that gap, the research team analysed electronic health records from the University of Pennsylvania Health System (Penn Medicine). They compared rates of alopecia among adults living with type 2 diabetes who began treatment with GLP-1 receptor agonists, SGLT-2 inhibitors or DPP-4 inhibitors.

The analysis covered people treated between January 2019 and September 2024. One comparison included 12,004 people taking GLP-1 receptor agonists and 15,221 taking SGLT-2 inhibitors. A second, separate comparison included 11,964 people taking GLP-1 receptor agonists and 11,233 taking DPP-4 inhibitors.

Accounting for differences between the treatment groups

The groups differed in several important respects before the researchers adjusted their results.

Compared with people taking SGLT-2 inhibitors, those taking GLP-1 receptor agonists were younger (mean age 58 v 65), had a higher body mass index (36.2 v 32.3), and had lower rates of cardiovascular disease and chronic kidney disease.

A similar pattern was seen in the comparison with DPP-4 inhibitors. People taking GLP-1 receptor agonists were again younger (mean age 58 v 67) and had a higher body mass index (36.2 v 31.3).

To limit the influence of these imbalances, the researchers adjusted for factors that might otherwise have shaped the findings, including age, sex, ethnicity, pre-existing conditions, use of other medications, and body mass index.

Higher rates of alopecia after adjustment

Once those adjustments were made, use of a GLP-1 receptor agonist was associated with a 37% higher risk of alopecia than use of an SGLT-2 inhibitor (6.91 v 5.04 per 1,000 person years).

The difference was larger in the second comparison. Risk was 68% higher among people taking GLP-1 receptor agonists than among those taking DPP-4 inhibitors (6.53 v 3.89 per 1,000 person years).

Further analysis indicated that the association was limited to non-scarring alopecia, the form in which hair follicles remain intact and the potential for regrowth is preserved. For this type of hair loss, risk was 53% higher among people taking GLP-1 receptor agonists than among those taking SGLT-2 inhibitors, and 72% higher than among those taking DPP-4 inhibitors.

Why rapid weight loss might disturb the hair cycle

The study did not establish why GLP-1 medications might be connected to hair loss, but the authors set out several plausible explanations.

Rapid weight loss is a well established cause of increased hair shedding. It may also contribute to iron or zinc deficiency, either of which can interfere with the normal hair growth cycle. Hormonal changes related to weight loss or to treatment itself could play a part as well, although further research will be needed to identify the mechanisms at work.

Important questions that remain open

The researchers acknowledged a number of limitations. The available clinical records did not contain enough detail to determine the severity, extent or duration of the alopecia. Nor could the team assess whether hair grew back after people stopped taking the medication.

Because the study was observational, it cannot demonstrate that GLP-1 medications directly caused the hair loss. Other factors that were not measured may have influenced the results.

Set against that, the authors described their work as rigorous, drawing on high quality data from a large and representative group of patients. The findings also held up across additional analyses, which supports their reliability.

What the findings mean for practice

For clinicians, the practical value of a study like this lies less in the headline percentages than in what it adds to the conversation before and during treatment. Anticipating adverse effects, recognising them early and folding them into shared decision-making are core parts of the GLP-1 consultation – the ground covered by CPD courses such as the College of Contemporary Health’s GLP-1RAs in Practice: How to Safely Prescribe Ozempic, Wegovy & Mounjaro, which works through initiation, titration and the avoidance of adverse reactions.

The researchers concluded: “Our findings extend previous anecdotal safety signals and provide more systematic evidence to inform clinical awareness of this potential adverse effect.”

CCH insight

Hair loss is unlikely to change prescribing decisions on its own, but it is exactly the kind of adverse effect that patients notice, worry about and sometimes stop treatment over. Knowing how to raise it, put the absolute risk in context and respond if it appears is part of delivering GLP-1 therapy well. CCH’s GLP-1RAs in Practice: How to Safely Prescribe Ozempic, Wegovy & Mounjaro (Or Any Other Weight Loss Drug) is a two-hour, CPD-accredited online course covering every stage of the consultation, from patient selection and titration through to managing adverse reactions, grounded in current NICE guidance and the ADA 2026 Standards of Care.

Find out more about GLP-1RAs in Practice →