Weight-Loss Drugs Like Ozempic and Mounjaro Linked to Higher Hair-Loss Risk, Study Finds

The blockbuster weight-loss and diabetes drugs that have reshaped modern medicine may carry an unwelcome side effect: hair loss. A large new study published July 22 in the BMJ found that people with type 2 diabetes taking GLP-1 receptor agonists — the class that includes Ozempic, Wegovy and Mounjaro — were significantly more likely to experience hair loss than patients on other diabetes medications.

Researchers led by a team at the University of Pennsylvania compared people with type 2 diabetes taking GLP-1 drugs against those using other treatments. They found that GLP-1 use was associated with a 37% higher risk of hair loss compared with SGLT-2 inhibitors, and a 68% higher risk compared with DPP-4 inhibitors — two other widely prescribed classes of diabetes medication.

There is a reassuring caveat. Further analysis suggested the effect was linked to non-scarring alopecia, a form of hair loss in which the follicles themselves remain intact. That means the shedding has the potential to reverse and hair can regrow, distinguishing it from the permanent, scarring types of hair loss. Some experts believe the phenomenon may be tied less to the drugs directly than to the rapid weight loss they cause, a stress response known as telogen effluvium that is also seen after crash diets, illness and childbirth.

The findings put hard numbers on a side effect that patients and doctors have discussed anecdotally for years. Hair loss is not prominently listed on the labels of the drugs, though clinical trials for Wegovy reported that about 3% of participants experienced it. The U.S. Food and Drug Administration has previously acknowledged "occurrences of hair loss following initiation of a GLP-1 receptor agonist, particularly semaglutide and tirzepatide" — the active ingredients in Ozempic and Wegovy, and in Mounjaro, respectively.

Regulators elsewhere are logging complaints too. So far in 2026, the U.K.'s Medicines and Healthcare products Regulatory Agency has received 399 reports of hair loss linked to tirzepatide and 148 tied to semaglutide, according to the study's authors. As tens of millions of people worldwide now take these medications, even a relatively uncommon side effect can translate into a large number of affected patients.

The researchers stressed that their observational study cannot prove the drugs directly cause hair loss, and that the benefits of GLP-1 medications for blood sugar, weight and cardiovascular health remain substantial for many patients. Still, they argued the results should be discussed with people starting the drugs, so that a temporary bout of thinning hair does not come as a frightening surprise — or prompt patients to abandon a treatment that is otherwise working.