What did the studies that raised concern find?
Two observational studies found more ED among men on GLP-1 drugs, and both deserve a careful read.
The first, a 2024 TriNetX database study, matched 3,094 non-diabetic men aged 18 to 50 with obesity who were given semaglutide against similar men who were not. New ED diagnoses or ED medicine use reached 1.47% in the semaglutide group versus 0.32% in the comparison group, a relative risk of about 4.5. A new diagnosis of low testosterone was also more common, 1.53% versus 0.80%.
The second, a 2026 target trial emulation, compared 4,910 men with type 2 diabetes starting a GLP-1 drug with 5,524 starting a DPP-4 inhibitor. ED occurred at 35.2 versus 28.0 per 1,000 person-years, a hazard ratio of 1.26. But after the authors calibrated for hidden bias using a negative control outcome, the association shrank and was no longer statistically significant. They concluded the findings may reflect residual or selection bias and do not establish causation.
What points the other way?
Randomized and weight-loss evidence leans toward benefit, or at least no harm.
| Study | Design | What it found | Main limit |
|---|---|---|---|
| TriNetX, 2024 | Health-record database | More ED codes with semaglutide | Cannot separate drug from detection |
| Target trial emulation, 2026 | Health-record database | Modestly more ED; not significant after calibration | Observational |
| REWIND, 2021 | Randomized, placebo-controlled | Slightly less new ED with dulaglutide, a GLP-1 drug | Exploratory analysis; different drug |
| Lifestyle trial, 2004 | Randomized | About a third of obese men regained normal function with weight loss | Diet and exercise, not a GLP-1 |
In REWIND, new moderate or severe ED occurred at 21.3 per 100 person-years with dulaglutide and 22.0 with placebo, and erectile scores declined less on the drug. The 2004 trial matters because weight loss is the main effect of semaglutide: 17 of 55 men in the program reached a normal erectile function score after two years, compared with 3 of 55 controls.
Why is the signal hard to interpret?
Because men who start a weight-loss medicine are different from men who do not, in ways a database cannot fully see. They have more contact with clinicians, more lab testing and more chances to be asked about erections, so an ED diagnosis that already existed can surface right after starting. Obesity, low testosterone and early vascular disease all cause ED on their own.
The rates are also small in absolute terms. In the 2024 study, the difference was roughly one extra ED diagnosis per hundred men, based on codes rather than examined function.
What should you check if ED starts after semaglutide?
Look for the causes that a weight-loss phase can stir up:
- Testosterone. A morning level is worth checking, since low testosterone was one of the signals in the 2024 study.
- Eating enough. A steep drop in calories and protein can leave you drained; see muscle loss on semaglutide.
- Mood and sleep. Fatigue, low mood and poor sleep all weigh on erections.
- Other medicines. Blood pressure, diabetes and mood medicines may need review as your weight changes.
- Timing and pattern. Do you still have morning erections? Did it begin before or after the dose went up?
Do not stop semaglutide on your own. Bring the list to the clinician managing it. Our blog post on whether GLP-1 drugs affect erections covers the research background, and does weight loss help ED covers the other side.
How Ultimate Male handles ED during weight loss
Ultimate Male treats both conditions under one roof, which makes this question easier to untangle. If ED appears during a semaglutide weight-loss program, a PA-C or MD at our San Gabriel or Downey clinic reviews when it started, your dose changes, intake and medicines, and orders on-site labs such as testosterone and glucose, with results in 24 to 48 hours.
The response depends on what turns up: adjusting the pace of weight loss, treating confirmed low testosterone, or adding erectile dysfunction treatment while you continue the medicine. Ask about it at your next check-in, or start with a free 10-minute call.
