A study of 50,000 users of weight loss jabs, such as Wegovy and Mounjaro, appears to confirm a link between them and a rare side effect of alopecia, according to findings published in the British Medical Journal.
People on the appetite-suppressing meds have been reporting hair loss to regulators, but it was not known whether it was caused by the drugs themselves. Although the overall risk is low, analysis of electronic patient data from the University of Pennsylvania Health System in the US appears to confirm the link.
Patients on weight loss drugs were 68% more likely to report hair loss than comparable patients on different diabetes medications, according to the findings.
Potential Causes and Expert Insight
Experts believe the hair loss could be caused by sudden drops in calorie intake and nutrient deficiencies. The US Food and Drug Administration is now investigating the possible side effect.
Dr Yong Chen, of the University of Pennsylvania, said: “Weight loss and changes in nutritional status… are established risk factors for telogen effluvium, a common and typically transient form of non-scarring hair loss, providing a plausible biological mechanism for this association. Although hair loss does not typically result in physical harm, it may have significant psychosocial consequences, affecting self-esteem, quality of life, and adherence to treatment.”
The study established a link with non-scarring alopecia — where hair follicles remain intact — leaving the potential for hair to regrow. It did not confirm whether hair grew back.
Study Details and Comparisons
Researchers looked at people with type 2 diabetes on GLP-1 drugs or other types of diabetes drugs known as SGLT-2 inhibitors and DPP-4 inhibitors. In total, 12,004 patients using GLP-1s were compared with 15,221 using SGLT-2 inhibitors, and a further 11,964 GLP-1 users were compared with 11,233 DPP-4 inhibitor users.
After adjusting for factors such as age and weight, researchers found that using GLP-1 drugs was associated with a 37% higher risk of alopecia than use of SGLT-2 inhibitors. GLP-1s were also linked to a 68% higher risk of hair loss than use of DPP-4 inhibitors.
Balancing Benefits and Risks
Dr Marie Spreckley, weight management researcher at Cambridge University, said: “Rapid weight loss is a recognised trigger for temporary hair shedding. Nutritional deficiencies, such as iron or zinc deficiency, may also contribute. This study provides important evidence that clinicians and patients should be aware of this potential adverse effect, but it should be interpreted in the context of the substantial and well-established benefits of GLP-1 receptor agonists for improving glycaemic control, reducing body weight, and lowering the risk of obesity-related complications. For many people, those benefits are likely to outweigh this relatively small potential risk.”
Common side effects of GLP-1 drugs also include vomiting and constipation. They require personalised support from specialists so that weight loss is maintained. The NHS prescribes the GLP-1 injections Mounjaro and Wegovy for weight loss but Ozempic only for diabetes.
