The Surprising Side Effects of Weight-Loss Drugs—Both Good and Bad
GLP-1 medications—like Ozempic, Wegovy (semaglutide), Saxenda, Victoza (liraglutide), Mounjaro, and Zepbound (tirzepatide)—aren’t just about curbing appetite and shedding pounds. These drugs impact much more than your waistline, and the effects, both positive and negative, can vary widely from person to person. Here’s what you might experience:
Muscle Loss
When you lose 15–25% of your body weight, up to 60% of that can be lean mass—muscle, bone, and more. The fix? Strength training. In one study of people taking liraglutide (Saxenda), those who lifted weights four times a week preserved more muscle than those who didn’t. A protein-rich diet also supports muscle maintenance, says Paul Titchenell, PhD, at the University of Pennsylvania.
Erectile Dysfunction (ED)
A recent study showed that men using semaglutide (Wegovy) for weight loss were more likely to experience ED and lower testosterone levels. This may be due to the drug interfering with hormone signaling, explains Joseph Sonstein, MD, at the University of Texas Medical Branch. The good news? The risk remains relatively low.
Nausea
GLP-1s activate a chemoreceptor zone in your brainstem—the area responsible for making you feel nauseated when something’s off. That’s why nausea is one of the most common side effects, especially with semaglutide. Adjusting your meal timing can help, so check in with your doctor for tips.
Gallstones
Rapid weight loss and slowed bile movement (a digestive fluid produced by the liver) can lead to gallstone formation. These pebble-like deposits can cause intense upper-right abdominal pain after eating. If that happens, seek medical help fast, says Dan Azagury, MD, a bariatric surgeon at Stanford.
Sagging Skin
So-called “Ozempic face”—loose skin, sagging cheeks, and deep wrinkles—isn’t exclusive to one drug. Any rapid weight loss can leave skin looking lax. Skin fibers don’t always bounce back easily after being stretched. A dermatologist or plastic surgeon can suggest treatments ranging from topicals to more intensive procedures, says Clinton Humphrey, MD, from the University of Kansas Medical Center.
A Stronger Heart
GLP-1 users have shown a reduced risk of heart attack, stroke, and cardiovascular death. That’s thanks not only to weight loss but also to the drugs’ ability to lower blood pressure, cholesterol, blood sugar, and inflammation, according to a Journal of Endocrinology review.
Possible Alzheimer’s Protection
Among people with type 2 diabetes, those who took semaglutide were 70% less likely to develop Alzheimer’s compared to those who only took insulin. Other GLP-1s also showed benefits—just not as dramatically.
Reduced Cravings
These meds help calm the urge to overeat—and may even help reduce cravings for alcohol, cigarettes, or opioids. “Appetite and addiction share brain pathways,” explains Stefan Trapp, PhD, of University College London, and GLP-1s seem to act on that overlapping system.
Liver Benefits
Excess weight often comes with fat buildup in the liver, leading to inflammation and even liver failure. Nearly half of men have Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). Losing 10% or more of your weight can significantly reduce liver fat—and GLP-1s may outperform other diabetes drugs in this area, says Paul Titchenell, PhD.
Lower Blood Sugar
Originally developed as diabetes treatments, GLP-1s help lower both blood sugar and A1C levels—the long-term marker of glucose control. According to Layla Abushamat, MD, at Baylor College of Medicine, better A1C levels reduce your risk of diabetes complications, including kidney failure and nerve damage.
Bottom Line:
GLP-1 drugs come with a host of effects—many beneficial, others worth watching. Talk to your doctor about what to expect and how to manage both the risks and rewards.
