This is one of the first questions I get from men considering testosterone replacement therapy, and it's a fair one. For years the internet has been full of conflicting answers — some sources say TRT is dangerous for your heart, others say that's outdated fear-mongering. The truth is that until recently, nobody actually had a great answer, because nobody had done the right kind of study. That changed in 2023 when the TRAVERSE trial was published in the New England Journal of Medicine. It's the largest and most rigorous look at this question we've ever had, and I want to walk you through what it actually found.
What kind of study was TRAVERSE?
TRAVERSE was what's called a randomized, double-blind, placebo-controlled trial. That's a mouthful, so let me break it down, because the study design is actually why the results matter.
- Randomized means every man who enrolled was assigned to either the testosterone group or the placebo group purely by chance — like a coin flip. That's important because it prevents the researchers from accidentally putting healthier men in one group and sicker men in the other.
- Double-blind means neither the patients nor the doctors seeing them knew who was getting real testosterone and who was getting a look-alike gel with no active ingredient. This prevents anyone's expectations from coloring the results.
- Placebo-controlled means there was a comparison group getting a fake treatment, so you can tell whether anything that happened was actually caused by the testosterone or would have happened anyway.
This is the gold standard for answering a medical question, and most of what you've read about TRT and heart health over the years came from weaker types of studies. TRAVERSE is a different tier of evidence.
Who was in the study?
5,246 men, ages 45 to 80, all with low testosterone and symptoms of it. Importantly, every man in the study either already had cardiovascular disease or was at high risk for it. In other words, this wasn't a group of healthy 35-year-olds — these were men the old FDA warnings were specifically worried about. If TRT was going to cause heart problems, this is the group where you'd expect to see it.
Half got a daily 1.62% testosterone gel, half got a matching placebo gel, and they were followed for an average of just over two years.
The headline result
For the main thing the study was designed to answer — does testosterone cause heart attacks, strokes, or cardiovascular death? — the answer was no. Men on testosterone had the same rate of major cardiovascular events as men on placebo. After years of conflicting information, that's a meaningful answer.
Testosterone therapy, in men who actually need it, does not appear to raise the risk of heart attack or stroke.
So where do blood clots come in?
Here's the nuance, and I want to be straight with you about it. While the main cardiovascular numbers looked reassuring, the researchers did find a few things that were slightly more common in the testosterone group:
- A small increase in atrial fibrillation (an irregular heart rhythm)
- A small increase in venous thromboembolism — meaning blood clots in the deep veins or lungs
- A small increase in acute kidney injury
The clot signal is the one most people ask me about. The absolute numbers were small, but the researchers themselves noted it and wrote that testosterone should be used with caution in men who have had a previous clotting event. That's the honest picture.
What this means for you
A few things I want you to take away from all of this:
First, the old narrative that TRT will give you a heart attack is not supported by the best evidence we have. For men who genuinely have low testosterone and symptoms, the cardiovascular safety picture is much better than the fear-based headlines of the 2010s suggested.
Second, the clot risk is not zero. If you have a personal or strong family history of deep vein thrombosis, pulmonary embolism, or a known clotting disorder, that's a real conversation to have with your provider before starting. It doesn't automatically disqualify you, but it changes the calculus and how we monitor you.
Third, "safe" in a trial is not the same as "safe on autopilot." The men in TRAVERSE were being monitored carefully. The same should be true for you — baseline labs, repeat labs at the right intervals, and a provider who's actually reading them. That's the standard of care, and frankly it's the standard every TRT patient deserves whether they're with me or someone else.
If you have questions about whether TRT makes sense for your situation, that's exactly what a free consultation is for. No pressure, no commitment — just a conversation with someone who's read the actual trial.