There’s no question that the wildly popular injectable weight-loss drugs help people drop pounds, lower heart-disease risk, manage obstructive sleep apnea, and more. But as more people use these drugs, which target hormones including GLP-1, doctors are learning more about the potential downsides, as well.
In the latest study published on MedRxiv—a site that hosts early research not yet peer reviewed by experts—scientists in Canada report that using GLP-1 drugs can contribute to a higher risk of hair loss, especially among women.
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Dr. Mohit Sodhi, a resident in emergency medicine at University of British Columbia, and his colleagues analyzed data from just over 1,900 people who were prescribed semaglutide and 1,300 who were prescribed bupropion-naltrexone—an older obesity treatment known as Contrave. Semaglutide is the compound in the drugs Ozempic, which treats diabetes, and Wegovy, which treats obesity. Sodhi focused only on people taking Wegovy to treat overweight or obesity to avoid any potential confounding effects of diabetes on hair loss.
He and his team then compared the diagnoses for hair loss in these patients’ medical records and found that those prescribed semaglutide had a 50% higher risk of being diagnosed with a hair-loss condition compared to those prescribed Contrave. That risk was twice as high for women as for men.
Read More: The Health Risks and Benefits of Weight-Loss Drugs
While it’s not clear why semaglutide is linked to greater hair loss than older weight-loss drugs, Sodhi says scientists have some theories. The first relates to the physiological stress that the body goes through under the influence of semaglutide. The drug contributes to a higher percentage of body-mass weight loss compared to previous weight-loss medications, and accomplishes this more quickly. “Because semaglutide causes greater weight loss and more rapid weight loss than Contrave, there is more physiologic stress on the body and therefore more hair loss,” he says.
Second, because the drug suppresses appetite, people who take it eat less and take in fewer nutrients, particularly protein, which is essential for hair growth. The gastrointestinal side effects associated with the drugs, which lead to nausea and vomiting, can further diminish people’s desire to eat and get the nourishment they—and their hair cells—need.
Is the risk enough to discourage people from using these drugs to lose weight? That depends on why they are taking the medications—whether to treat diabetes or obesity—and how much of a health risk those health conditions pose. If you’re trying to manage diabetes, “you may be more willing to accept the potential risk of hair loss than someone who may be using semaglutide to lose a few pounds to look good for an event,” Sodhi says.
Results like this, and additional studies on the longer terms effects of GLP-1 drugs, are important to helping people balance the risks and benefits of these medications. “If people don’t know the potential side effects,” says Sodhi, “then they may be getting into something they didn’t sign up for.”