Medicines known as GLP-1 receptor agonists have become some of the most popular treatments for type 2 diabetes and obesity.
Drugs such as semaglutide and tirzepatide can lower blood sugar, help people lose weight, and reduce the risk of several health problems. While these medicines offer important benefits, researchers continue to study their possible side effects.
A new study published in The BMJ suggests that people taking GLP-1 receptor agonists may have a slightly higher chance of developing hair loss, also known as alopecia, than people using other common diabetes medicines. The researchers stress that the overall risk is still low, but patients and doctors should be aware of this possible effect when choosing treatment.
Scientists from the University of Pennsylvania Health System analyzed electronic health records from adults with type 2 diabetes between January 2019 and September 2024.
They compared more than 12,000 people who started GLP-1 medicines with over 15,000 people using SGLT-2 inhibitors. They also compared nearly 12,000 GLP-1 users with more than 11,000 people taking DPP-4 inhibitors.
People taking GLP-1 medicines were generally younger and had a higher body mass index than those in the comparison groups. The researchers carefully adjusted for these and many other differences, including age, sex, ethnicity, medical conditions, and the use of other medicines, to make the comparison as fair as possible.
After these adjustments, people using GLP-1 receptor agonists had a 37% higher risk of hair loss than those taking SGLT-2 inhibitors. Compared with DPP-4 inhibitors, the risk was 68% higher. Even so, the number of people affected remained small, with only a few cases occurring for every 1,000 people each year.
The increased risk was mainly linked to nonscarring alopecia. In this type of hair loss, the hair follicles are not permanently damaged, meaning the hair may grow back over time. This finding is reassuring because it suggests the condition is often not permanent.
The researchers believe rapid weight loss may explain part of the problem. Losing weight quickly can temporarily interrupt the normal hair growth cycle. Weight loss may also reduce levels of nutrients such as iron or zinc, both of which are important for healthy hair growth.
The study could not determine exactly how severe the hair loss was, how long it lasted, or whether it improved after people stopped taking the medicines. The researchers also could not completely rule out other factors that might have affected the results.
Although the findings are important, they should be viewed alongside the proven benefits of GLP-1 medicines for diabetes and obesity. For many people, these drugs greatly improve blood sugar control and reduce the risk of serious health complications.
Overall, this large study provides stronger evidence that hair loss may be an uncommon side effect of GLP-1 receptor agonists.
Patients who notice unusual hair shedding should speak with their healthcare provider rather than stop treatment on their own. The results highlight the importance of balancing possible side effects with the many health benefits these medicines can provide.
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Source: University of Pennsylvania Health System.
