If you have been reading about testosterone replacement therapy, you have almost certainly run into the same scary claim from both sides. One camp says TRT protects your heart. The other says it quietly damages it. For years, the honest answer was that nobody truly knew, because the studies were small and pointed in different directions, and one trial back in 2010 was even stopped early over heart worries.
That uncertainty is exactly why a large study called TRAVERSE matters so much. It is also why the FDA changed what testosterone labels are allowed to say in 2025. In this blog post, we will discuss whether testosterone therapy is really safe for your heart, what the TRAVERSE trial actually found, what the new FDA decision means for you, and when this is a conversation worth having with your own clinician.
What Was the TRAVERSE Trial?
TRAVERSE was a large randomised, placebo-controlled trial, which is the most reliable kind of study we have. It enrolled 5,246 men who had two things at the same time. They had confirmed low testosterone with symptoms, and they also had heart disease or a high risk of developing it.
That detail is essential. These were not healthy men in their forties chasing a performance edge. These were men already carrying real cardiovascular risk, which is the very group doctors worry about most.[1]
The men received either testosterone gel or a placebo gel, and they were followed for around 33 months, close to three years. The main question was simple. Would testosterone cause more major cardiac events, such as heart attack, stroke, or cardiovascular death, than the placebo?[1]
What Did TRAVERSE Actually Find?
The headline result was reassuring. Testosterone was noninferior to placebo for major cardiac events, with a hazard ratio of 0.96 (95% CI 0.78 to 1.17). In plain language, the testosterone group did not have meaningfully more heart attacks, strokes, or cardiac deaths than the placebo group. A cardiovascular event happened in 7.0% of the testosterone group and 7.3% of the placebo group.[1]
It is worth being precise about what “noninferior” means, because this is where many online summaries go wrong.
Noninferior means testosterone did not do worse than placebo on the main outcome. It does not mean testosterone is good for your heart, and it does not mean therapy is free of risk. It means the old fear of a big heart-attack signal was not confirmed in the men who were studied.
What About the Safety Signals? This Part Matters
Here is the part an honest article cannot skip. Even though the headline was reassuring, TRAVERSE reported higher rates of three other problems in the testosterone group. These were atrial fibrillation, which is an irregular heartbeat, pulmonary embolism, which is a blood clot in the lung, and acute kidney injury.[1]
The trial was not designed to prove that testosterone causes these, so they need more study before anyone calls them certain. However, they are not something to wave away either. If you have a personal or family history of an irregular heartbeat, blood clots, or kidney trouble, these are exactly the things to raise with your clinician before you start, and not after. You can read more about how blood thickening is tracked on therapy in our guide to hematocrit monitoring on TRT.
What Did the FDA Decide in 2025?
This is the part most blog posts have not caught up with, and it is the single most useful thing for you to know. In February 2025, the FDA issued class-wide labelling changes for every testosterone product in the United States, based on TRAVERSE and on follow-up blood-pressure studies. (FDA, Class-Wide Labeling Changes for Testosterone Products, 2025)
Two things changed, and they pull in opposite directions, which is why this deserves your attention.
The FDA removed the old boxed warning language about increased cardiovascular risk. That warning had been on the label for about a decade, and it was the reason TRAVERSE was ordered in the first place. Because the trial did not confirm a major heart-attack and stroke signal, the strongest cardiovascular warning came off.
However, at the same time, the FDA added a brand new warning about increased blood pressure. The follow-up monitoring studies showed that testosterone can raise blood pressure, so that warning is now required across the whole class.
So the regulators did not simply declare testosterone safe. They swapped out a fear the data did not support, and swapped in a risk the data did support. That is what careful drug regulation looks like, and it is essential to know if your blood pressure already runs high. The label also still states clearly that these products are approved only for men with a genuine medical cause of low testosterone, not for the normal dip that comes with age.
Does the Wider Research Agree?
Largely, yes. A meta-analysis pooling 30 randomised trials in 11,502 men found no increased risk of cardiovascular events, heart attack, stroke, or death with testosterone compared to placebo.[2]
A separate analysis of 26 trials in 10,941 men found no significant difference in atrial fibrillation, clots, or death.[3] A further review focused only on men with clearly low testosterone reached the same reassuring conclusion.[4]
The pattern across these large studies is consistent. In men with genuine, confirmed low testosterone who are treated under proper medical supervision, the overall heart picture is reassuring. That is very different from saying testosterone is safe for anybody who wants it. For the broader picture, see our overview of testosterone therapy and cardiovascular risk.
What About Prostate Cancer Risk?
TRAVERSE looked at this too. The hazard ratio for high-grade prostate cancer in the testosterone group was 1.62 (95% CI 0.39 to 6.77), which did not reach statistical significance. However, that confidence interval is very wide, which tells you the trial was not powered to rule out a real increase. So this is one to discuss with a urologist if your prostate health is a concern.[5]
One caveat keeps this honest. Men who already had a raised PSA above 3.0 ng/mL were screened out before the trial began. So these findings apply to men who were already checked and cleared, and not to men with an existing prostate concern.
So What Does This Mean for You?
A few honest points are worth holding on to here.
The reassuring heart data applies to men with a proper diagnosis of low testosterone who are treated and monitored correctly. It does not apply to testosterone bought online, used without a diagnosis, or taken for performance. The new blood-pressure warning is real, so if your blood pressure already runs high, that belongs in the conversation. And your wider history matters too, because the irregular-heartbeat, clot, and kidney signals are about you as a whole person, not just your testosterone number.
If you fall into the group TRAVERSE studied and you are treated properly, you can rest assured that the strongest old fear about testosterone and heart attacks was not borne out by the best trial we have.
When Should You See a Clinician?
If you have symptoms that could point to low testosterone, such as ongoing low energy, reduced libido, low mood, or loss of muscle, the first step is a proper evaluation rather than a self-diagnosis from an online checklist. That means fasting morning bloodwork, done correctly.
Both the Endocrine Society and the American Urological Association are clear on this. Testosterone therapy is appropriate only for men with confirmed low levels plus symptoms, measured on at least two morning tests.[6][7]
If you are already on therapy and worried about your heart, the worst move is to stop suddenly on your own. Bring your concerns, and your recent blood-pressure readings, to the clinician who prescribes for you.
Conclusion
On balance, the research today is more reassuring than the frightening headlines of a decade ago. The largest trial we have did not confirm the big heart-attack signal people feared, and in 2025 the FDA agreed by removing that cardiovascular boxed warning. However, the same year the FDA added a new blood-pressure warning, which is a useful reminder that reassuring and risk-free are not the same thing. For men with a real diagnosis who are properly monitored, testosterone therapy looks safer for the heart than it once did. Your own clinician is still the person who turns this evidence into the right decision for you.
References
- [1] Lincoff AM et al., N Engl J Med. 2023, PMID 37326322
- [2] Jaiswal V et al., Prog Cardiovasc Dis. 2024, PMID 38589271
- [3] Sood A et al., Endocr Pract. 2023, PMID 37797887
- [4] Cannarella R et al., Asian J Androl. 2023, PMID 37921515
- [5] Bhasin S et al., JAMA Netw Open. 2023, PMID 38150256
- [6] Bhasin S et al., J Clin Endocrinol Metab. 2018, PMID 29562364
- [7] Trost L. J Urol. 2024, PMID 38456434
Medically reviewed by Ahmed Zayed, MBBCh, a clinician with 12 years of practice. This article is for education and does not replace a consultation with your own doctor.
