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 showed men who started TRT had higher rates of cardiovascular events, and those studies got enormous media coverage, and they shaped clinical practice for years, with many doctors refusing to prescribe testosterone to anyone with a history of heart disease.

The problem was the studies themselves.

Observational research tracks what people do in real life and then looks for patterns, which sounds reasonable until you realize that men who sought out testosterone therapy in that era were often older, sicker, and already had more cardiovascular risk factors than men who never pursued it, and then researchers counted their heart attacks and blamed the testosterone, when the more likely explanation was that the kind of men who needed TRT were already the kind of men more likely to have a heart attack. That is called confounding, and it is one of the most common ways observational research produces false alarms.

The only way to actually answer the question was a randomized controlled trial, where you take a large group of men, randomly assign half to TRT and half to placebo, and follow them long enough to count real events like heart attacks, strokes, and cardiovascular deaths.

That trial was called TRAVERSE, published in the New England Journal of Medicine in 2023, and it was the largest cardiovascular safety trial ever conducted specifically on testosterone replacement therapy.

The researchers enrolled 5,246 men between 45 and 80 years old, all of whom had confirmed low testosterone levels, defined as below 300 nanograms per deciliter, and all of whom already had either established cardiovascular disease or a high risk of developing it, which means this was not a healthy sample, these were exactly the men that most doctors had been most afraid to treat. They were randomized to either a testosterone gel targeting levels between 350 and 750 nanograms per deciliter or a placebo gel, and they were followed for a median of roughly 22 months, with some men followed for up to four years.

The primary outcome was what researchers call MACE, which stands for major adverse cardiovascular events, and specifically means nonfatal heart attack, nonfatal stroke, or cardiovascular death combined into a single endpoint.

The TRT group had a MACE rate of 7.0 percent. The placebo group had a rate of 7.3 percent. That difference was small enough that statistically it could easily be due to chance, and the trial was specifically designed to test whether TRT was noninferior to placebo, meaning it would only fail if TRT was meaningfully worse, and it was not. The confidence interval on the hazard ratio crossed 1.0, which means the data are consistent with TRT having no effect on cardiovascular risk at all.

That result was then placed into context by a meta-analysis published in JACC in 2024 that pooled TRAVERSE together with every other randomized controlled trial on testosterone therapy and cardiovascular outcomes, and the combined analysis covering tens of thousands of patient-years of follow-up reached the same conclusion: no statistically significant increase in heart attacks, strokes, or cardiovascular mortality in men receiving TRT compared to placebo.

An expert review published in Andrology in 2026 that specifically examined the clinical implications of TRAVERSE and the surrounding evidence confirmed that finding again.

So the short answer to the question of whether TRT raises your risk of a heart attack is no, based on the best available evidence, and that is a meaningful shift from what the field believed even a decade ago.

But stopping there misses something important about how the biology actually works.

Testosterone does things inside your body that are not inherently dangerous but that require monitoring to stay safe. One of the most significant is its effect on red blood cell production. Testosterone stimulates the production of something called erythropoietin in the kidneys, which is a hormone that tells your bone marrow to produce more red blood cells, and more red blood cells means your blood becomes thicker, and thicker blood is harder to pump and more prone to forming clots inside your vessels.

The measurement that tracks this is called hematocrit, which is simply the percentage of your blood that is made up of red blood cells. A normal hematocrit for an adult male is somewhere between 38 and 50 percent. In TRAVERSE, elevated hematocrit occurred more often in the TRT group than the placebo group, and once hematocrit climbs above 54 percent, the clotting risk becomes real and clinically meaningful, which is why that number is the threshold most guidelines use to prompt dose reduction or a temporary pause in therapy.

The other system that requires attention is your lipid profile. Testosterone, particularly when converted into estrogen through a process called aromatization, can have complex effects on HDL cholesterol, the kind associated with lower cardiovascular risk, and those effects vary depending on the form of testosterone, the dose, and the individual, which is why checking a full lipid panel regularly is not optional monitoring, it is how you catch a problem before it compounds.

This is where the practical reality diverges from the simple clinical finding.

TRAVERSE showed that TRT is not inherently dangerous for your heart, and that is true. But the trial was conducted under controlled conditions where men were monitored, where hematocrit was tracked, where dose adjustments happened when needed, and where the researchers were paying attention. The average man who gets a testosterone prescription from his doctor and does not return for six months of bloodwork is operating in a completely different situation.

The TRAVERSE finding does not give you permission to ignore your labs. It tells you that testosterone, managed correctly, does not add cardiac risk. Managed incorrectly, it can thicken your blood, shift your lipids, and sit inside a body that is getting less cardio and eating worse because the user mistakenly believes the testosterone is handling everything.

The injection changes one variable. You still own the rest.

What the last decade of research actually clarified is that the fear was misplaced but the caution was not, and the distinction between those two things is the entire point.

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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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