Weight loss drugs like Mounjaro ‘linked to hair loss’, researchers say

Weight loss and diabetes drugs such as Mounjaro, Ozempic and Wegovy are linked to an increased risk of hair loss, researchers have said.

People taking GLP-1 stimulant drugs have reported hair loss to regulators, but a new study involving around 50,000 people appears to strengthen the link.

Researchers used electronic patient data from the University of Pennsylvania Health System to compare rates of alopecia, a form of hair loss, in adults using GLP-1 drugs to manage diabetes with those taking other medications.

The team noted that regulators in the US had already received reports linking the drugs to hair loss, particularly semaglutide (Wegovy and Ozempic) and tirzepatide (Mounjaro).

So far in 2026, the UK Medicines and Healthcare products Regulatory Agency (MHRA) has received 399 reports of hair loss linked to tirzepatide, following 541 reports last year.

It has also received 148 reports of hair loss associated with semaglutide, alongside 164 reports last year.

For the new study, researchers examined people with Type 2 diabetes taking GLP-1 receptor stimulants and compared them with patients using other diabetes drugs.

After adjusting for factors that could affect the results, including age and weight, researchers found GLP-1 use was associated with a 37% higher risk of alopecia compared with one of the other types of drugs, SGLT-2 inhibitors

GLP-1 drugs were also linked to a 68% higher risk of hair loss compared with another type, known as DPP-4 inhibitors.

Further analysis suggested the association was linked to non-scarring alopecia, where hair follicles remain intact, and hair has the potential to regrow.

The researchers, including from the University of Pennsylvania in the US, wrote in the British Medical Journal (BMJ) that case reports and analyses of the US Food and Drug Administration (FDA)’s Adverse Event Reporting System describe “occurrences of hair loss”.

They single out semaglutide (Wegovy and Ozempic) and tirzepatide (Mounjaro) as being particularly higher risk, and say the FDA has “indicated that it is evaluating this potential safety signal”.

“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,” researchers add.

On the reasons why people may suffer hair loss while on the drugs, the team said the “most likely mechanism” relates to weight loss and “reduced caloric intake”, though more research is needed.

They said restricting calories may “contribute to physiological stress and micronutrient deficiencies (for example, iron, zinc, biotin), which can disrupt the hair growth cycle”.

Other factors may include the “metabolic, hormonal, and immunological effects attributed to GLP-1 receptor agonists that may influence hair follicle growth and cycling”.