6 minutes of readingJOSH*, 35 YEARS OLD, COULD easily go weeks or even months without sex. That is, until he created Mounjaro two years ago. In a few months, he had lost 11 kilos, while regaining the raging libido and erections of a teenager.
David*, 75, had the opposite experience. A few weeks after starting Wegovy, his sexual desire plummeted and he had difficulty reaching an orgasm.
These were temporary changes that seemed to subside as the men continued to take their GLP-1 medications. Still, their stories raise important questions that researchers are trying to answer as the drugs gain popularity.
In a Kinsey Institute 2025 SurveyMore than half of GLP-1 users said the drug had affected their sex lives, but trends were split: 16% said desire had decreased, while 18% said it had increased, and 16% said sexual function had improved while 12% said it had deteriorated. Moreover, the men were about twice as likely as women to report these changes, whether positive or negative.
With American GLP-1 use quadrupled since 2024it is worth considering whether these changes can be attributed to the medications themselves or simply to the physical and physiological effects that accompany the treatment.
GLP-1 Drug Research and Sexual Health
Well, first know that the clinical evidence is limited and what does exist doesn’t really clarify things.
In one Observational study 2025Semaglutide users were more likely to receive a new diagnosis or prescription for erectile dysfunction. But this is correlation, not causation.
Other studies showed that taking dulaglutide for four weeks had no effect on desire, and long-term use of dulaglutide is associated with slightly lower risk moderate to severe erectile dysfunction. But the first study had a small sample size and the second was funded by Eli Lily and Company, maker of the GLP-1 Zepbound, raising possible conflict of interest concerns.
We therefore need independent research on a larger scale. “Nothing in the scientific literature so far shows that GLP-1 RA drugs actually cause changes in sexual desire or erectile dysfunction in this population,” says Marsha NovickMD, family and obesity medicine physician and medical director of Weight management and well-being online.
Another wrinkle, according to Jay LutharMD, Harvard-trained internist and founder of Lutanen Health: Liraglutide, semaglutide, and tirzepatide are often grouped under the GLP-1 umbrella, but they are not actually the same. Results regarding one should therefore not be automatically applied to the others.
“Distinguishing the effects of medications from the effects of weight loss, metabolic improvement, nausea, fatigue, mood changes, and pre-existing dysfunction requires prospective study designs that do not yet exist,” explains Evan AppelbaumMD, cardiologist and medical director of Men’s Health Boston.
Why GLP-1 might increase your libido, even before significant weight loss
WE KNOW THAT obesity and metabolic dysfunction can contribute to low testosterone levels and erectile challenges, and that GLP-1 can increase testosterone. It is therefore logical that sexual desire may increase as the number on the scale decreases. According to Dr. Appelbaum, vascular function and nitric oxide signaling, which also play an important role in erections, also tend to improve with weight loss.
But several different mechanisms work simultaneously, says Dr. Luthar. Beyond metabolic and hormonal changes, losing weight can also increase energy and self-confidence, which may mean feeling more inclined to initiate or having greater stamina in bed.
“These psychological changes are not trivial: desire is a global experience that cannot be separated from the way a man feels about himself,” adds Dr. Appelbaum.
Christopher*, 44, says his libido was at an all-time low when he started Mounjaro three years ago. Seeing his body change, Christopher began to feel better about himself. This self-confidence motivated him to hit the gym and pursue a romantic relationship. He said his penis seemed even bigger as the weight came off. Just six weeks after starting treatment, he noticed a slight increase in his libido, which increased further after three months.
Overall, Dr. Luthar says he suspects that most obese men on GLP-1 experience positive effects on their sexual health. That said, he acknowledges that some experience the opposite — and researchers still don’t know how common these negative effects are, or what exactly drives them.
Why GLP-1 could decrease your libido
NAUSEA, FATIGUE, HEADACHES, indigestion, diarrhea – these are just some of the Most common side effects of GLP-1which may help explain why some men experience a drop in desire.
“I guess the most boring explanation is the most common,” says Dr. Luthar. “If you’re nauseous, tired, eating very little, and losing weight quickly, you won’t feel very sexy.”
Another possible explanation: GLP-1 drugs promote weight loss in part by dampening “food noise” and reducing appetite – and that’s because they seem influence the brain’s reward systemDr. Luthar said.
“They reject food cravings,” he explains. “So it’s fair to ask whether they might also be reducing their sexual interest.”
Animal studies suggest that these drugs can modify reward-related behavior. But as Dr. Luthar points out, it’s still unclear whether these changes translate into sexual desire in humans.
“These studies often use doses and delivery methods that don’t match how people take these drugs, and you can’t ask a mouse what its libido is,” he adds.
Matthew Miller37 years old, family nurse practitioner and clinical director at Men’s Health Gamedayclaims his libido dropped four weeks after starting tirzepatide and six weeks after starting semaglutide. This change coincided with a broader feeling that he likens to anhedonia, or a diminished interest and pleasure in things that once brought joy. Fortunately, Miller says his libido returned to normal after reaching a stable maintenance dose.
Why Your Erections and Libido May Move in Opposite Directions
FIRST, THERE IS A important distinction to make between libido, erectile function and orgasm.
“Desire and erections are related, but they are different systems,” says Dr. Luthar. “Desire lives primarily in the brain. It’s about motivation, hormones, mood, energy, and how things are going in your relationship. Erections are mostly about the plumbing and wiring, that is, 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 feeling less interest in sex because you’re tired, nauseous, or a little emotionally flat.
Case in point: Dr. Appelbaum says he treated two different men who both lost about 40 pounds, but while one noticed an increase in desire and erections, the other noticed his desire was decreasing, despite the fact that his erections remained functional and his testosterone levels were unchanged.
Orgasm is another piece of the puzzle. A Analysis 2025 Adverse event reports from the FDA have identified orgasm-related complaints, although researchers have still not been able to establish whether the drugs were the cause.
“Some (men on GLP-1 therapy) describe a decrease in orgasmic intensity: they can reach orgasm, but it is less satisfying,” adds Dr. Appelbaum. “Some describe an orgasm that is delayed or requires effort.”
Will the changes last and what can you do about it?
FOR SOME OF In the men we spoke with, sexual changes improved as other side effects disappeared. That said, experts agree that any bothersome changes, especially if they negatively impact your mood or relationship, should always be shared with your doctor. Be sure to tell your doctor when symptoms started and if they seem to get worse with increasing dose.
According to Dr. Luthar, it’s also important to consider any changes in mood and sleep, which may be linked to sexual desire and drive. Your doctor may also order hormonal and heart health tests, as new erectile problems can be warning signs of low testosterone as well as cardiovascular disease.
“We also want to rule out issues like thyroid problems, alcohol, stress and relationship problems,” he says.
The good news is that there may be a relatively simple solution that does not require giving up the medication and its benefits. For example, Dr. Luthar says this may mean slowing 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 treatment against the quality of life impact of persistently reduced libido.”
Whatever you do, don’t assume that your ability to get an erection – or complete one – isn’t supposed to be taken seriously.
“Your sex life is part of your health,” says Dr. Appelbaum. “Your doctor should know this.”
*Names have been changed to protect the confidentiality of the sources.
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 wellness. His work has appeared in Business Insider, Men’s Health, USA TODAY, Healthline, Health.com, Bustle and other national publications. She is also the creator and host of WELL-BENT, an evidence-based wellness podcast, in which she explores the complex and often misunderstood issues surrounding modern wellness through conversations with clinicians, researchers, and other experts.
Rebecca is an alumna of Emerson College and 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 microphone,…
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