Huy Luong Save Story Save this story Save Story Save this story When you’re dealing with new period changes and bouts of fatigue that coincides with starting a GLP-1 medication, an eyebrow raise is only natural—especially when most chatter about the drugs’ side effects is focused on nausea and diarrhea (how glamorous!). But as the drug category becomes more widely-used, patients are reporting other symptoms that don’t make it on the label , and a new Nature Health study dives into them.
For the study, researchers conducted an AI analysis of 400,000 Reddit posts shared over more than five years to find an array of symptoms reported by people who use semaglutide (Ozempic, Wegovy, and Rybelsus) and tirzepatide (Mounjaro and Zepbound).
Researchers found posts from 67,008 users on well-known side effects like nausea, vomiting, constipation, and diarrhea. More interestingly, they also discovered symptoms that aren’t typically linked with GLP-1s. Some of the more commonly-reported yet surprising complications were fatigue, menstrual irregularities, chills, and hot flashes.
It’s worth noting that other studies have looked at the drugs’ effects on everything from nail-biting to hair loss , suggesting that the list of official side effects linked with these medications may grow with time. Separately, it seems increasing numbers of people are obtaining these medications through outside of their doctors office , which, as Allure has previously reported, can coincide with patients taking higher-than-recommended doses or following aggressive titration schedules that could increase the possibility of side effects that might not happen when the drugs are taken as directed. This gray market also makes it difficult for those patients to get the appropriate care they need if side effects do surface.
But back to the study: To be clear, it did not conclusively prove that GLP-1s caused these side effects—it just established a link—and some of them may be due to weight loss rather than the medications themselves. But the researchers wrote in the study that these findings are worth digging into deeper, noting that they “highlight patient concerns not well captured in current labelling or trials.”
While some of the symptoms flagged aren’t the ones everyone associates with these medications, health care providers who treat patients on GLP-1s say they’ve heard them all before.
Even with some of the more commonly associated side effects—like hair loss and skin changes—a lot of it is believed to be due to the rapid weight loss many patients experience when taking GLP-1 medication (up to 20% of their body weight over 72 weeks) rather than the drug itself.
But there are changes that happen in the body beyond fat loss while someone is on a weight loss journey, says Mir Ali , MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA. “Many are tied to changes in hormones,” he says.
Studies have found that circulating levels of estrogen typically drop in women when they lose significant amounts of weight, Dr. Ali explains. In men, testosterone levels tend to increase with weight loss. These hormone changes could play a role in some of the surprising side effects flagged in the study, but not all of them.
Of the side effects highlighted in the new study, changes in menstrual cycles “make the most sense to me clinically,” says Kelley Gregorovic , MS, a board-certified family nurse practitioner at Tufts…