JOSH*, 35, COULD easily go weeks—or even months—without sex. That is, until he started Mounjaro two years ago. Within a few months he’d lost 11 pounds, while gaining the raging libido and erections of a teenager.
David*, 75, meanwhile, had the opposite experience. A few weeks after starting Wegovy, his sexual desire plummeted and he had difficulty reaching an orgasm.
These were temporary shifts that seemed to subside as the men continued on their GLP-1 medications. Still, their stories are raising important questions that researchers are trying to untangle as the meds boom in popularity.
In a 2025 Kinsey Institute survey, more than half of GLP-1 users reported that the medication had affected their sex lives—but the direction was divided: 16 percent said desire went down, while 18 percent said it went up, and 16 percent said sexual function improved while 12 percent said it worsened. What’s more, men were about twice as likely as women to report these shifts, either positive or negative.
With U.S. GLP-1 usage quadrupling since 2024, it’s worth examining whether these changes can be blamed on the medications themselves—or merely the physical and physiological effects that come along with treatment.
The research on GLP-1 meds and sexual health
WELL, FIRST KNOW that clinical evidence is limited—and what does exist doesn’t exactly clear things up.
In one 2025 observational study, semaglutide users were more likely to get a new erectile-dysfunction diagnosis or prescription. But that’s correlational, not causational.
Other studies have found that taking dulaglutide for four weeks had no effect on desire, and long-term dulaglutide use is associated with a slightly lower risk of moderate to severe erectile dysfunction. But the first study involved a small sample size and the second was funded by Eli Lily and Company, makers of the GLP-1 Zepbound, which raises possible conflict of interest concerns.
So we need more large-scale, independent research. “Nothing so far in the scientific literature shows GLP-1 RA medication is actually causing changes in sexual desire or erectile dysfunction in this population,” says Marsha Novick, MD, a family medicine and obesity medicine doctor and medical director of Weight Management & Wellness Online.
Another wrinkle, according to Jay Luthar, MD, a Harvard-trained internist and founder of Lutanen Health: Liraglutide, semaglutide, and tirzepatide are often lumped together under the GLP-1 umbrella, but they’re not actually identical—so findings about one shouldn't automatically be applied to the others.
“Distinguishing drug effects from the effects of weight loss, metabolic improvement, nausea, fatigue, mood changes, and preexisting dysfunction requires prospective study designs that largely don't yet exist,” says Evan Appelbaum, MD, a cardiologist and medical director of Men's Health Boston.
Why GLP-1s might increase your sex drive—even before major weight loss
WE KNOW THAT obesity and metabolic dysfunction can contribute to low testosterone and erectile challenges, and that GLP-1s may increase testosterone. So, it makes sense that sexual desire might rise as the number on the scale drops. According to Dr. Appelbaum, vascular function and nitric oxide signaling, both of which also play a strong role in erections, also tend to improve with weight loss.
But there are several different mechanisms operating simultaneously, says Dr. Luthar. Beyond the metabolic and hormonal changes, losing weight can also boost energy and self-confidence—which can mean feeling more inclined to initiate, or having greater stamina in the bedroom.
"These psychological changes are not trivial—desire is a whole-person experience that cannot be separated from how a man feels about himself,” Dr. Appelbaum adds.
Christopher*, 44, says his sex drive was at an all-time low when he first started Mounjaro three years ago. As he watched his body change, Christopher started feeling better about himself. That bump in confidence motivated him to hit the gym, and pursue a romantic relationship. He says his penis even looked bigger as the weight came off. Just six weeks into treatment, he noticed an uptick in his libido, which ramped up even further at three months.
Overall, Dr. Luthar says he suspect most men on GLP-1s with obesity experience positive effects on sexual health. That said, he acknowledges that some experience the opposite—and researchers still don't know how common those negative effects are, or what exactly is driving them.
Why GLP-1s might decrease your sex drive
NAUSEA, FATIGUE, HEADACHES, indigestion, diarrhea—these are just some of the most common side effects of GLP-1s, which may help explain why some men experience a dip in desire.
“The more boring explanation is, I suspect, the more common one,” Dr. Luthar says. “If you’re nauseous, tired, eating very little, and losing weight fast, you’re not going to feel very sexy.”
Another possible explanation: GLP-1 medications partly promote weight loss by quieting “food noise” and curbing appetite—and that’s because they seem to influence the brain's reward system, says Dr. Luthar.
“They turn down cravings for food,” he explains. “So, it’s fair to ask whether they could dial down sexual interest as well.”
Animal studies suggest that these medications can alter reward-related behavior. But as Dr. Luthar points out, it’s still unclear whether those changes translate to sexual desire in humans.
“Those studies often use doses and delivery methods that don’t match how people take these drugs, and you can’t ask a mouse how his libido is,” he adds.
Matthew Miller, 37, a family nurse practitioner and clinical director at Gameday Men's Health, says his sex drive plummeted within four weeks of starting tirzepatide and six weeks of starting semaglutide. That change coincided with a broader feeling he likens to anhedonia, or reduced interest and pleasure in things that used to bring joy. Fortunately, Miller says his libido returned to normal after he reached a stable maintenance dose.
Why your erections and sex drive might move in opposite directions
FIRST, THERE’S AN important distinction to make between libido, erectile function, and orgasm.
“Desire and erections are related, but they’re different systems,” says Dr. Luthar. “Desire lives mostly in the brain. It’s motivation, hormones, mood, energy, and how things are going in your relationship. Erections are mostly plumbing and wiring, meaning healthy blood vessels and nerves, with the brain flipping the switch.”
So, it’s entirely possible to have stronger or more frequent erections as your vascular health improves, while simultaneously experiencing less interest in sex because you’re tired, nauseous, or a little emotionally flatlined.
Case in point: Dr. Appelbaum says he treated two different men who both lost around 40 pounds—but while one saw a surge in desire and erections, the other noticed his desire dwindled, despite the fact that his erections remained functional and his testosterone levels were unchanged.
Orgasm is another piece of the puzzle. A 2025 analysis of FDA adverse-event reports identified some orgasm-related complaints, although researchers still haven't been able to establish whether the medications are the culprit.
“Some [men on GLP-1 therapy] describe a blunting of orgasmic intensity—they can achieve orgasm, but it is less satisfying,” adds Dr. Appelbaum. “Some describe delayed or effortful orgasm."
Will the changes last—and what can you do about them?
FOR SOME OF the men we spoke with, sexual changes improved as other side effects resolved. That said, experts agree that any bothersome shifts, especially if they’re negatively impacting your mood or relationship, should always be shared with your prescriber. Make sure to tell your doctor when the symptoms started, and whether they seemed to worsen along with dose increases.
According to Dr. Luthar, it’s also important to consider any changes in mood and sleep, which can be connected to sexual desire and drive. Your doctor may order hormone and heart health testing, too, since new erectile problems can be warning signs of low testosterone as well as cardiovascular disease.
“We also want to rule out things like thyroid problems, alcohol, stress, and relationship issues,” he says.
The good news is there may be a relatively simple fix that doesn’t require giving up the medication—and its benefits. For example, Dr. Luthar says that may mean slowing down the dose increases, checking for nutrient deficiencies, and treating underlying causes like low testosterone.
“I have patients in this category who have improved with dose reduction,” says Dr. Appelbaum. “I have others where we have had to weigh the metabolic benefits of continuing the medication against the quality-of-life impact of persistent libido blunting.”
Whatever you do, don’t assume your ability to get an erection—or finish—isn’t meant to be taken seriously.
“Your sex life is part of your health,” says Dr. Appelbaum. “Your physician needs to know.”
*Names have been changed to protect sources’ privacy.
Rebecca Strong is a Boston-based health and wellness journalist who covers everything from nutrition and fitness to mental health, psychology, and the science behind everyday well-being. Her work has appeared in Business Insider, Men's Health, USA TODAY, Healthline, Health.com, Bustle, and other national publications. She's also the creator and host of WELL-BENT, an evidence-based wellness podcast where she explores the messy, often misunderstood questions surrounding modern wellness through conversations with clinicians, researchers, and other experts.
Rebecca is an alumna of Emerson College and The Boston Conservatory at Berklee, and her music can sometimes be heard on Boston radio stations, including 92.5 The River and Country 102.5. When she's not reporting or on the mic, she's usually chasing after her mischievous toddler, trying desperately to keep just one houseplant alive, or tinkering with her espresso machine in pursuit of the perfect iced honey latte.