The headline: a possible signal, not a proven side effect
Right now, nobody can tell you with confidence that GLP-1 medicines cause erectile dysfunction. One widely shared study found more ED diagnoses in younger men without diabetes who were given semaglutide. Other data, including a large randomized trial and decades of weight-loss research, point toward better erectile function as men lose weight and improve their metabolic health.
Both can be true at once. A medicine can help most men’s erections through weight loss while a smaller group runs into trouble for other reasons, or the early signal can turn out to be an artifact of who gets these medicines. The sections below walk through what each study actually measured.
The study that raised the question
In 2024, urologists published a TriNetX database study in the International Journal of Impotence Research. They pulled health records for men aged 18 to 50 with a BMI over 30 and no diabetes, then compared men who received semaglutide after June 2021 with matched men who never did.
- 3,094 men in each group, average age about 38 and average BMI about 39.
- New ED diagnosis or ED pill: 1.47% with semaglutide vs 0.32% without, a relative risk of 4.5.
- New testosterone deficiency diagnosis: 1.53% vs 0.80%, a relative risk of 1.9.
A relative risk of 4.5 sounds alarming. In absolute terms, though, roughly 15 of every 1,000 men on semaglutide received an ED diagnosis or ED medicine over the study window, compared with about 3 of every 1,000 men not on it. Those are small numbers, and the study design matters a great deal in interpreting them.
Why confounders keep the link uncertain
Database studies like this one can show that two things travel together. They cannot show that one causes the other, and several features of this study make that distinction important.
- More doctor visits, more diagnoses. Men starting a new weight-loss medicine are seen and asked about their health more often. Problems that existed before may simply get recorded.
- Diagnosis codes, not exams. The outcome was a billing code or a new ED pill, not a measured change in erectile function.
- Who chooses treatment. Men who seek a GLP-1 may differ from matched controls in ways records do not capture, such as mood, sleep, alcohol use or motivation to address sexual health.
- Rapid change. Fast weight loss, reduced food intake, fatigue and nausea in the first months could affect libido or erections temporarily, which is a different issue from lasting harm.
A 2026 target trial emulation in men with type 2 diabetes illustrates the problem. It compared 4,910 men starting a GLP-1 medicine with 5,524 starting a DPP-4 inhibitor and found a modestly higher ED rate on GLP-1 drugs (35.2 vs 28.0 per 1,000 person-years). When the authors applied a check for hidden bias using control outcomes, the association weakened and was no longer statistically significant. They wrote that the findings may reflect residual or selection bias and do not establish causation.
The evidence pointing the other way
Randomized data, the strongest kind, lean toward benefit rather than harm. In the REWIND trial of dulaglutide, an older GLP-1 medicine, 3,725 men with type 2 diabetes completed erectile function questionnaires over several years. New moderate or severe ED occurred at 21.3 per 100 person-years with dulaglutide and 22.0 with placebo, a small reduction. Men on dulaglutide also had a smaller decline in erectile function scores. This was an exploratory analysis, and the trial was funded by the drug’s maker.
Then there is weight loss itself. In a 2004 randomized trial in JAMA, 110 men with obesity and ED were assigned to an intensive diet and exercise program or general advice. After two years, 17 of 55 men in the intervention group reached a normal erectile function score, compared with 3 of 55 controls. Improvements tracked with lower BMI, more activity and less inflammation. Our answer on whether weight loss helps ED covers that research in more detail.
What this means for men on a GLP-1
If you are taking semaglutide or tirzepatide and your erections are fine, there is no reason to worry based on current evidence. If you notice a change, it deserves attention, but not panic and not a sudden stop.
Several things are worth checking before blaming the medicine:
- Testosterone. Low testosterone can lower desire and affect erections. Weight loss often raises it, as our article on whether losing weight raises testosterone explains, but not in every man.
- Blood pressure medicines. As weight drops, blood pressure often falls too, and a dose that was right before may now be too strong.
- Eating and energy. Very low intake, dehydration and poor sleep can all blunt sexual function.
- Mood. Depression and anxiety affect erections, and a significant body change can stir up both.
- Underlying vascular disease or diabetes, which may have been there before treatment started.
A simple log helps your provider sort these out. Note when the change started, whether it followed a dose increase, how you are eating and sleeping, and whether desire, erections or both have shifted. A problem that tracks with the first weeks of a higher dose and fades as side effects settle points somewhere different from one that keeps worsening month after month.
Our answer page on semaglutide and erectile dysfunction gives a shorter version of this checklist.
How Ultimate Male handles ED during weight loss
Because the same clinic manages both, Ultimate Male can look at erections and weight loss together rather than in separate offices. A man on our medical weight loss program who reports a change in erections gets a review of his labs, including morning testosterone, along with his medicine list, blood pressure and dose timeline.
If an ED treatment makes sense, the provider explains the options for erectile dysfunction and checks them against everything else you take. If the GLP-1 plan itself needs adjusting, that conversation happens with the same team. Start with the free 10-minute call if you want to talk it through first.
