Is Testosterone Therapy Safe for Your Heart? What the Research Actually Shows

If you've looked into testosterone replacement therapy (TRT) and also read that it might be bad for your heart, you're not imagining things. For close to a decade, testosterone products carried an FDA-mandated warning about cardiovascular risk. That warning shaped a lot of the caution you still hear from clinicians and see in online discussions. But the evidence base has changed substantially since then, and it's worth walking through what actually happened, what the newest and largest trial found, and where real caution still belongs.

Why this question exists in the first place

The concern didn't come out of nowhere. A 2010 trial of testosterone gel in older men with mobility limitations, the TOM trial, was stopped early after researchers noticed more cardiovascular events in the group taking testosterone than the group taking placebo (Basaria et al., NEJM 2010). Three years later, a large observational study in JAMA found an association between testosterone therapy and higher rates of heart attack, stroke, and death in a group of veterans with pre-existing heart disease (Vigen et al., JAMA 2013).

Those two studies, plus a few others with mixed results, were enough for the FDA to add a cardiovascular warning to testosterone product labels in 2015. At the same time, the agency narrowed the approved use of testosterone to men with a confirmed medical condition causing low testosterone, rather than age-related decline alone, and it required manufacturers to run a dedicated trial to settle the question (FDA Drug Safety Communication, 2015).

That trial took nearly a decade to complete. It's called TRAVERSE, and it's the best evidence we have.

What the largest trial to date actually found

TRAVERSE enrolled more than 5,200 men, ages 45 to 80, who had low testosterone along with either existing cardiovascular disease or a high risk of developing it. Half received testosterone gel, half received placebo, and researchers tracked major cardiac events -- heart attack, stroke, and cardiovascular death -- for an average of about two years (Lincoff et al., NEJM 2023).

The result: testosterone therapy was not associated with a higher rate of these major cardiac events compared to placebo. That's a meaningfully different picture than the earlier, smaller studies suggested, and because TRAVERSE was specifically designed to answer the cardiovascular safety question -- with a much larger sample and a population that already carried heart disease risk -- it carries more weight than the studies that prompted the original warning.

That said, TRAVERSE wasn't all reassurance. Men on testosterone had higher rates of atrial fibrillation (an irregular heart rhythm), acute kidney injury, and venous thromboembolism (blood clots, usually in the legs or lungs) than men on placebo. None of those are trivial, and they're part of why monitoring during treatment still matters even with a better safety signal on the headline outcome.

Who still needs a more careful conversation

Averages from a trial don't erase the value of an individual risk assessment. A few groups deserve extra caution before starting TRT:

• Men with a recent heart attack or stroke. TRAVERSE excluded men with a cardiac event in the prior six months, so the strongest safety data doesn't directly apply to that window.
• Men with untreated severe sleep apnea. Testosterone can worsen sleep apnea, which independently strains the cardiovascular system.
• Men with a history of blood clots or a clotting disorder. Given the clot signal in TRAVERSE, this history changes the risk-benefit calculation.
• Men with significantly elevated red blood cell counts (hematocrit) at baseline. Testosterone raises hematocrit further, and above a certain threshold that increases clotting and stroke risk.

None of these rule out treatment automatically. They're reasons to have a specific, individualized conversation rather than starting on a standard protocol.

What monitoring actually looks like

Because the risks that showed up in TRAVERSE -- clots, arrhythmia, kidney injury -- are things that can often be caught early, ongoing monitoring is part of responsible TRT, not an optional add-on. A reasonable monitoring plan typically includes:

• Hematocrit and a complete blood count before starting, then periodically during treatment, since rising red blood cell counts are one of the more common and manageable issues
• Blood pressure checks, since testosterone can raise blood pressure in some men
• A lipid panel, since testosterone's effect on cholesterol varies and is worth tracking individually
• PSA and a prostate discussion, which relates to prostate rather than cardiac risk, but is a standard part of safe TRT monitoring
• A direct check-in about new symptoms: leg swelling or pain, chest discomfort, shortness of breath, or a racing or irregular heartbeat

If hematocrit climbs too high, the usual response is adjusting the dose or interval, not necessarily stopping therapy altogether.

The honest bottom line

The cardiovascular story on TRT has genuinely improved. The best current evidence, from the largest and most rigorously designed trial, does not show an increased risk of heart attack, stroke, or cardiovascular death. That's real, useful information, and it's fair to feel more reassured than the 2015 warning label would have allowed.

At the same time, "no increased risk of the top-line events" isn't the same as "no cardiovascular considerations at all." The clot and arrhythmia signals in TRAVERSE mean monitoring still earns its place, and men with recent cardiac events or clotting histories fall outside the population the trial reassures most confidently. The right approach is usually not "TRT is dangerous" or "TRT is risk-free," but a specific plan built around your own cardiac history, baseline labs, and symptoms.

If you're considering testosterone therapy and want to understand where you personally fall on that spectrum, that conversation is worth having with a clinician who can review your labs and history directly. Visit our men's health page to learn more about how we approach testosterone evaluation and treatment. Most major plans are accepted, including Medicare, so getting a clear answer on your own cardiovascular risk shouldn't be something you pay out of pocket to find out.