2026-07-23 12:05:31
Weight-loss jabs including Mounjaro and Wegovy may leave users with more than just a slimmer waistline, with new research suggesting they also increase the risk of hair loss.
Scientists found people taking GLP-1 medications were up to 68 per cent more likely to develop alopecia than those using other diabetes drugs, with the effect appearing strongest around a year after starting treatment.
Researchers at the University of Pennsylvania analysed more than 50,000 health records comparing people taking semaglutide, sold as Wegovy, and tirzepatide, sold as Mounjaro, with patients prescribed alternative diabetes medicines.
The study found those taking GLP-1 drugs were 68 per cent more likely to experience hair loss than people using DPP-4 inhibitors and 37 per cent more likely than those taking SGLT-2 inhibitors.
The increased risk was seen in both men and women but appeared to be greater in women.
Separate figures from the UK’s Medicines and Healthcare products Regulatory Agency show there have already been 940 reports of hair loss linked to tirzepatide since the start of 2025, along with 312 reports involving semaglutide.
Researchers believe the condition is a form of non-scarring alopecia, meaning hair follicles remain intact and regrowth is possible.
The team wrote: “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.”
Scientists said the most likely explanation is that rapid weight loss and reduced calorie intake can lead to nutritional deficiencies that disrupt the normal hair growth cycle.
They suggested shortages of nutrients including iron, zinc and biotin may contribute, while hormonal, metabolic and immune changes caused by the drugs could also play a role.
The researchers added: “Our findings extend previous anecdotal safety signals and provide more systematic evidence to inform clinical awareness of this potential adverse effect.”
Despite the findings, experts stressed the overall risk remains small.
Dr Marie Spreckley, a weight-management researcher at the University of Cambridge, who was not involved in the study, said: “It is important to interpret these findings alongside the absolute risk, which remained low.”
She added the increased risk equated to “around two to three additional clinically recorded cases of hair loss per 1,000 person-years of treatment compared with the alternative diabetes medications”.
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