Common weight loss injections such as Mounjaro, Ozempic and Wegovy may be associated with a higher chance of hair loss, new research suggests.
These medicines, known as GLP-1 agonists, imitate a naturally occurring hormone that helps control blood sugar levels and suppress appetite. Their use has risen sharply as more people turn to them for weight loss.
Now, researchers at the University of Pennsylvania Health System say findings from a study involving roughly 50,000 people appear to back up increasing reports of hair loss among some patients taking the drugs.
The researchers examined alopecia rates in adults using GLP-1 medications for type 2 diabetes and compared them with patients taking other types of diabetes treatment. The comparison showed a higher rate among GLP-1 users.
Specifically, the study assessed people taking GLP-1 receptor agonists against those prescribed SGLT-2 inhibitors or DPP-4 inhibitors, which are two other categories of diabetes medication.
Altogether, 12,004 GLP-1 users were compared with 15,221 patients on SGLT-2 inhibitors. A separate comparison looked at 11,964 GLP-1 users and 11,233 people taking DPP-4 inhibitors.
After taking into account factors including age and weight, the team found that GLP-1 use was tied to a 37 percent greater risk of alopecia than SGLT-2 inhibitors, and a 68 percent greater risk than DPP-4 inhibitors.
Writing in the British Medical Journal (BMJ), as reported by Sky News, the researchers pointed to prior case reports and data from the Food and Drug Administration’s Adverse Event Reporting System that had already flagged hair loss following the start of GLP-1 treatment, “particularly semaglutide (Wegovy and Ozempic) and tirzepatide (Mounjaro).”
The FDA has said it is reviewing the possible safety signal, and recent product labeling reflects that hair loss has been observed in some trials of weight-loss formulations. In current U.S. labeling, Wegovy lists hair loss among reported adverse reactions, and Zepbound’s prescribing information also lists hair loss as a common adverse reaction. By contrast, Mounjaro is approved for type 2 diabetes and its U.S. label does not list hair loss among the common adverse reactions, although alopecia has been reported after approval in the postmarketing section.
According to the researchers, the “most likely mechanism” behind the hair loss is weight loss itself, rather than the drugs directly attacking hair follicles.
They said fast and substantial weight loss, along with lower calorie intake, can place stress on the body and potentially cause deficiencies in nutrients such as iron, zinc and biotin. Those deficiencies may interfere with the normal hair growth cycle. They also noted that metabolic, hormonal and immune-related changes linked to GLP-1 drugs could influence how hair follicles grow and cycle, though they said more study is needed to identify the precise cause.
The researchers also emphasized that, while hair loss is not usually physically dangerous, it should not be brushed aside as unimportant.
They wrote that it “may have significant psychosocial consequences, affecting self-esteem, quality of life, and adherence to treatment,” meaning it could even lead some patients to stop taking medication they still need for diabetes management.
The study adds to a wider debate over the side effects of GLP-1 drugs as their use continues to expand across the US, where millions of people now take them for diabetes treatment and weight management. Some clinicians say hair loss may be more likely to appear in people who lose weight quickly, whether the trigger is medication, diet change or a combination of both.
Novo Nordisk, the company behind Ozempic and Wegovy, said in a statement:
“Patient safety is our priority. As with all medicines, treatments for chronic conditions can cause side effects that vary between individuals and should only be used under the supervision of a healthcare professional.
“Ozempic is not licensed for weight loss, and no evidence of hair loss was found in Novo Nordisk’s type 2 diabetes clinical trials.
“Hair loss was reported in Wegovy trials and is listed as a side effect. Most cases were mild, non-serious, and resolved or improved during treatment. Hair loss was reported in 3% of Wegovy-treated adults compared with 1% receiving placebo, and investigators considered more than half the cases unlikely to be related to the medication.
The manufacturers of Mounjaro have also been approached for comment.