Does TRT Raise Heart Attack Risk? What the New Research Actually Shows

The fear made sense at the time. Observational studies from the early 2010s suggested that men on testosterone replacement therapy had higher rates of heart attacks and strokes, and that sent a wave of concern through the medical community that took years to unpack.

The problem with those studies was not the question they were asking. It was how they tried to answer it.

Observational research watches what happens to people who are already making choices, and men who seek out testosterone therapy are often older, heavier, and have more existing metabolic dysfunction than men who do not, so when researchers compared TRT users to non-users and found more cardiovascular events in the TRT group, they were largely measuring the difference between sick men and healthier men, not the effect of testosterone itself. The technical term for this is something called confounding, which is when an outside variable explains the relationship you are seeing better than the variable you are actually studying.

To get a clean answer, you need a randomized controlled trial, where you take a large group of similar people and randomly assign them to treatment or placebo so that all the confounders wash out and you can actually see what the drug is doing.

That is exactly what the TRAVERSE trial was designed to do.

Published in the New England Journal of Medicine in 2023, TRAVERSE enrolled 5,246 men between the ages of 45 and 80 who had documented low testosterone and who already had either established cardiovascular disease or a high risk of developing it, meaning these were not healthy young men, these were the people you would most expect to be harmed if testosterone were genuinely dangerous to the heart.

Half were randomized to testosterone gel titrated to keep their levels between 350 and 750 nanograms per deciliter, and half received placebo gel. The trial ran for an average of nearly 22 months, with some men followed for close to three years.

The primary outcome they were tracking was something called MACE, which stands for major adverse cardiovascular events and includes heart attack, stroke, and cardiovascular death combined into a single measure.

In the testosterone group, 7 percent of men experienced a MACE event. In the placebo group, 7.3 percent did. That is not a statistically significant difference, and it means testosterone did not increase the risk of the outcomes that people had been most worried about.

The 2024 meta-analysis published in JACC pulled TRAVERSE together with every other qualifying randomized controlled trial on testosterone therapy and confirmed the finding across a broader evidence base, and the 2026 expert review in Andrology, which took a close look at the TRAVERSE data alongside the accumulated RCT literature, reached the same conclusion: testosterone replacement therapy, when used appropriately in men with low testosterone, does not increase cardiovascular risk compared to placebo.

So the fear, at its core, was built on the wrong kind of evidence and has now been directly tested and not supported.

But there is a part of this story that the headline does not capture, and it is the part that actually determines whether any individual man on TRT stays healthy or ends up in trouble.

TRAVERSE looked at testosterone therapy as a treatment administered within a clinical framework, with regular monitoring, dose titration, and follow-up. It was not studying men who get a prescription, ignore their labs, and treat the therapy as a substitute for everything else.

One of the most reliable physiological effects of testosterone therapy is an increase in red blood cell production, specifically an increase in something called hematocrit, which is the percentage of your blood volume made up of red blood cells. Testosterone signals the kidneys to produce more erythropoietin, which is a hormone that drives the bone marrow to generate more red blood cells, and this can be a good thing in men who were previously anemic from low testosterone, but when hematocrit climbs too high, the blood becomes viscous in a way that raises clotting risk meaningfully.

The threshold that clinicians watch is 54 percent. Above that level, the increased thickness of the blood creates enough mechanical friction in the vessels and enough clotting factor concentration that the risk of thrombosis, which is a clot forming inside a blood vessel, becomes a real clinical concern rather than a theoretical one. In TRAVERSE, elevated hematocrit was significantly more common in the testosterone group than in the placebo group, and venous thromboembolism, which is clotting events in the deep veins or lungs, occurred at a slightly higher rate in men on testosterone.

This is not a reason to avoid therapy. It is a reason to monitor.

The practical structure for staying safe on TRT is not complicated. Bloodwork every six months at minimum, with hematocrit being one of the primary values to watch. Lipid panels to ensure the therapy is not quietly shifting your cholesterol in an unfavorable direction. And the cardiovascular habits that existed before the prescription, meaning aerobic exercise, dietary quality, and body composition management, need to continue because TRT does not replace those inputs.

The men who get into trouble are almost always the men who interpret the prescription as the solution rather than as one piece of a broader system.

Testosterone therapy optimizes a hormonal environment. It does not offset the damage from a sedentary lifestyle or poor metabolic habits, and it does not monitor your own physiology for you.

What the TRAVERSE trial actually settled is the narrower question: does testosterone, by itself, in men who need it and are being monitored, increase the risk of heart attack and stroke? The answer from the best evidence we now have is no.

The broader question, which is whether any man on TRT stays cardiovascularly healthy, is answered not by the therapy itself but by what he does around it.

That has always been true. The research just finally caught up.

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References

1. Lincoff AM, et al. 2023. "Cardiovascular Safety of Testosterone-Replacement Therapy." New England Journal of Medicine. Source
2. Zitzmann M, et al. 2026. "Cardiovascular Safety of Testosterone Therapy: Insights from the TRAVERSE Trial and Beyond." Andrology. Source
3. Hudson J, et al. 2024. "Long-term Cardiovascular Safety of Testosterone-Replacement Therapy in Middle-Aged and Older Men: A Meta-Analysis of Randomized Controlled Trials." JACC. 04050-6 Source

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