Does TRT Raise Heart Attack Risk? What the New Research Actually Shows
The fear around testosterone replacement therapy and heart attacks did not come from nowhere. It came from a wave of observational studies published in the early 2010s that seemed to show men on TRT were having more cardiovascular events, and those studies spread fast, and they shaped how doctors talked to patients about this for a decade.
The problem is that observational studies cannot prove causation, and the ones that raised the alarm had real design flaws, including comparison groups that were not well matched and populations where sick men were more likely to get prescribed testosterone in the first place, which means the sicker outcome was already baked into the data before the study even started.
To understand what the newer research actually found, it helps to know what TRT is doing in the body at a basic level.
Testosterone is a hormone produced primarily in the testes that regulates a wide range of systems, including muscle, bone density, red blood cell production, libido, mood, and cardiovascular function. When levels fall below roughly 300 nanograms per deciliter, the body starts losing function across all of those systems. TRT is the medical replacement of that hormone through injections, gels, or pellets to bring levels back into a normal physiological range.
The cardiovascular concern always centered on two main pathways. First, testosterone stimulates something called erythropoiesis, which is the production of red blood cells, and more red blood cells means thicker blood, which means higher risk of clotting. Second, there was a concern that testosterone could worsen lipid profiles by dropping HDL cholesterol, the kind associated with cardiovascular protection.
Both of those mechanisms are real, which is what made the fear feel reasonable. The question was never whether those mechanisms exist. The question was whether the overall cardiovascular outcome for men on TRT was worse.
That is what the TRAVERSE trial was designed to answer.
TRAVERSE, published in the New England Journal of Medicine in 2023, enrolled 5,246 men between the ages of 45 and 80 who had low testosterone, defined as two separate readings below 300 nanograms per deciliter, and who also had either existing cardiovascular disease or high risk for it. Researchers randomly assigned them to receive testosterone gel or placebo and followed them for an average of just under three years. The primary outcome they were watching for was a composite of cardiovascular death, nonfatal heart attack, and nonfatal stroke.
The result was that TRT did not increase that composite risk compared to placebo. The incidence rate in the testosterone group was 7.0 percent versus 7.3 percent in the placebo group, which was not a statistically significant difference, but it did not go in the direction the fear predicted.
This was not a study of healthy young men optimizing performance. This was a study of older men with real cardiovascular risk who were the exact population doctors were most worried about putting on testosterone. And in that population, over nearly three years, the cardiovascular event rates were essentially equal.
A meta-analysis published in the Journal of the American College of Cardiology in 2024 pooled TRAVERSE with every other randomized controlled trial that had been done on TRT and cardiovascular outcomes, and it confirmed the same finding. Across the combined data, testosterone replacement did not significantly increase major adverse cardiovascular events compared to placebo. An expert review published in Andrology in 2026 looked at all of this evidence together and reached the same conclusion.
So the answer to the headline question is no, TRT in hypogonadal men does not appear to raise the risk of heart attack, stroke, or cardiovascular death when managed appropriately.
But there is a part of this that the trials do not protect you from, and that is how most men actually use TRT in practice.
The TRAVERSE trial was a controlled environment where participants had regular monitoring and protocol adherence. That is not what happens when a man gets a prescription, fills it, and then treats the injection as a substitute for everything else he was supposed to be doing.
The erythropoiesis pathway mentioned earlier is the most concrete short-term risk. Testosterone raises red blood cell production, and if hematocrit, which is the percentage of your blood that is made up of red blood cells, climbs above 54 percent, the blood becomes viscous enough that clotting risk rises meaningfully. This is not theoretical. TRAVERSE actually showed a statistically significant increase in pulmonary embolism in the testosterone group, which suggests the clotting pathway is real and does activate, it just did not translate into increased heart attacks or strokes in that study at those levels of monitoring.
The practical implication is that hematocrit needs to be checked regularly, and if it climbs toward that threshold, the dose needs to be adjusted or a therapeutic phlebotomy, which is a controlled blood draw to reduce red blood cell concentration, needs to happen before it becomes a problem.
Lipids need the same attention. LDL cholesterol did not rise significantly in TRAVERSE, but HDL dropped modestly in the testosterone group, and over a long enough timeline in a man who is also not exercising and eating well, those lipid shifts compound.
The men who end up in trouble on TRT are almost never the ones who were carefully monitored. They are the ones who got the prescription and interpreted it as permission to stop doing the other work, and then several years later they have elevated hematocrit, worsening lipid panels, no cardio base, and a body that is now running on testosterone without any of the lifestyle inputs that make testosterone cardioprotective in the first place.
The research shows TRT is safe. The research also assumes you are doing your part.
Bloodwork every six months at minimum, hematocrit watched closely, lipids tracked, cardiovascular exercise maintained. These are not add-ons. They are what separates TRT as a tool from TRT as a liability.
Testosterone did not cause those observational-era heart attacks. Unmanaged risk factors caused them. TRT just got blamed because it was the variable that changed. The actual lesson from a decade of better research is that the hormone is not the problem, and neither is the prescription, but the system around the prescription still has to work.
References
- Lincoff AM, et al. 2023. "Cardiovascular Safety of Testosterone-Replacement Therapy." New England Journal of Medicine. Source
- Zitzmann M, et al. 2026. "Cardiovascular Safety of Testosterone Therapy: Insights from the TRAVERSE Trial and Beyond." Andrology. Source
- 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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