Testosterone and Heart Safety: What the TRAVERSE Study Shows

For years, men and their doctors faced an unsettling uncertainty: does testosterone replacement therapy (TRT) raise the risk of heart attacks and strokes? Earlier signals were conflicting, and the question had real stakes given how many men take testosterone.

The TRAVERSE trial, published in the New England Journal of Medicine in 2023, was designed specifically to answer it. In more than 5,200 middle-aged and older men with low testosterone and existing or high risk of heart disease, TRT did not increase the rate of major adverse cardiac events such as heart attack, stroke, or cardiovascular death, compared with placebo (Lincoff et al., 2023).

That is genuinely reassuring, and it is the headline. But it is not a clean bill of health. The same study found more cases of atrial fibrillation, pulmonary embolism, and acute kidney injury in the testosterone group, results the researchers themselves called unexpected (Cleveland Clinic, 2026). So the honest answer is nuanced: reassuring on heart attacks and strokes, but not risk-free, and only studied in men who genuinely needed treatment.

What you will learn:

• What the TRAVERSE study set out to answer
• What it actually found, both reassuring and cautionary
• Who the results apply to, and who they do not
• What this means for men considering or taking TRT
• The questions still worth asking your doctor

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Why This Question Mattered So Much

Testosterone use has risen sharply. A study in JAMA found that testosterone prescribing among US men aged 30 and older roughly tripled in the early 2000s (Baillargeon et al., 2018). As use grew, so did concern.

Some earlier observational studies and a couple of small trials had hinted at possible cardiovascular harm, enough that in 2015 the US Food and Drug Administration required a warning about a possible increased risk of heart attack and stroke on testosterone product labels. But the evidence was inconsistent. Other studies suggested no harm, or even benefits in men with conditions like metabolic syndrome (European Expert Panel, 2025).

The result was genuine uncertainty. Men with real symptoms of testosterone deficiency, and the doctors treating them, were left weighing a treatment against a poorly defined heart risk. A large, well-designed trial was needed to settle it. That is what TRAVERSE set out to be.

What Was the TRAVERSE Study?

TRAVERSE was a large, randomised, double-blind, placebo-controlled trial, the most rigorous kind of study for questions like this. It was requested by the FDA precisely to resolve the cardiovascular safety question.

Key features (Lincoff et al., 2023):

The choice of participants matters and is easy to miss. This was not a study of young, healthy men taking testosterone to build muscle. It was a study of older men with genuine, symptomatic testosterone deficiency who already had, or were at high risk of, heart disease, the group where the safety question was most pressing. That focus shapes exactly who the results apply to.

The primary endpoint, MACE, is a standard combined measure: death from cardiovascular causes, non-fatal heart attack, and non-fatal stroke.

The Main Finding: Reassuring on Heart Attacks and Strokes

Here is the central result. Testosterone therapy was non-inferior to placebo for major adverse cardiac events, meaning it did not increase the rate of heart attacks, strokes, or cardiovascular deaths (Lincoff et al., 2023).

This finding was consistent with the broader evidence. Reviewing TRAVERSE alongside earlier trials, expert panels concluded that testosterone therapy does not increase overall cardiovascular risk in men for whom it is appropriately prescribed (Mayo Clinic Proceedings, 2024). Notably, across the major trials, there were numerically fewer MACE events in the testosterone groups, not more, though the trials were designed to test safety rather than to prove benefit.

The researchers also looked at whether testosterone’s known effect of raising red blood cell count (haematocrit) translated into more cardiovascular events, and found no association between the change in haematocrit and MACE (Androgen Society, 2024).

For men with genuine testosterone deficiency who need treatment, this is meaningful reassurance that the therapy is not driving the heart attacks and strokes that earlier warnings raised concern about.

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The Cautionary Findings: Not a Clean Bill of Health

Responsible reporting means giving equal weight to the safety signals, because they are real and clinically relevant.

Alongside the reassuring MACE result, three adverse events occurred at a significantly higher rate in the testosterone group than in the placebo group (Cleveland Clinic, 2026; trted.org, 2025):

A few points give these findings context:

• The lead investigator noted that testosterone appears safe from a cardiovascular standpoint but is “not without adverse effects,” and that the higher rates of atrial fibrillation and acute kidney injury had not been seen in previous studies (Cleveland Clinic, 2026).
• The increase in pulmonary embolism (a blood clot in the lungs) was consistent with prior concerns, and it supports existing guidance to use testosterone cautiously in men with a history of blood clots (HCPLive, 2026).
• Atrial fibrillation is an irregular heart rhythm that itself raises stroke risk over time, so this signal is not trivial even though overall MACE did not rise.

These were secondary findings, and some experts note that when pooled with other trials the arrhythmia signal did not reach statistical significance (European Expert Panel, 2025). But they were unexpected enough that researchers flagged them clearly and called for further study. They are the reason “testosterone is safe for the heart” is an oversimplification.

A separate TRAVERSE finding worth knowing: testosterone was also associated with a higher risk of bone fractures, another unexpected result now being studied further (Snyder et al., 2024).

Who These Results Apply To (and Who They Don’t)

This is the most important section for reading the study correctly, because misapplying it is easy.

The results apply to:

• Middle-aged and older men (45 to 80)
• With genuinely low testosterone and symptoms of deficiency
• Who have or are at high risk of cardiovascular disease
• Using prescribed, medically supervised testosterone at replacement doses

The results do NOT tell us about:

• Young, healthy men with normal testosterone taking it for muscle, performance, or “optimisation”
• Men using high, supraphysiologic doses, as in anabolic steroid misuse
• Women
• People using testosterone without a genuine medical indication or medical supervision

This distinction is not a technicality. TRAVERSE studied replacement therapy for a genuine deficiency, not testosterone as an enhancement drug. Its reassurance on heart attacks and strokes cannot be stretched to cover recreational or performance use, where doses are often far higher and the risk picture is entirely different and less studied.

What This Means If You Are Considering or Taking TRT

TRAVERSE changed the conversation from “we are not sure if this is dangerous” to “this does not appear to raise heart attack and stroke risk, but it has specific side effects to watch.” That is useful, and it should inform a discussion with your doctor rather than a decision made alone.

Reasonable takeaways for a conversation with your clinician:

• TRT for genuine, symptomatic testosterone deficiency does not appear to increase heart attack or stroke risk, which is reassuring if you have been worried.
• It is not free of cardiovascular-related effects. Atrial fibrillation, blood clots in the lungs, and kidney injury occurred more often, so these deserve monitoring.
• A history of blood clots is a specific reason for caution, and something to raise explicitly.
• Testosterone should be prescribed for a diagnosed deficiency confirmed by symptoms and blood tests, not taken speculatively.
• Ongoing monitoring matters, including blood counts and a check on heart rhythm and kidney function as your doctor advises.

The overall message from expert bodies is that testosterone therapy used as indicated is reasonable and cardiovascularly safe in terms of major events, with a clear-eyed view of its specific risks (Cleveland Clinic, 2026).

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Important Context and Limitations

A few caveats help you weigh the study fairly.

• It was a safety trial, not a benefit trial. TRAVERSE was designed to test whether TRT is harmful to the heart, not to prove it improves outcomes. It does not establish that testosterone is beneficial for the heart.
• High discontinuation. Nearly 60% of participants had stopped their assigned treatment by 48 months, which can affect how the long-term results are interpreted (trted.org, 2025).
• Specific population. The findings are most applicable to the men studied and should not be generalised to everyone.
• Secondary signals need confirmation. The atrial fibrillation, kidney, and fracture findings were unexpected and require further research to fully understand.

None of this undermines the core reassurance on MACE. It simply frames it accurately: a strong answer to one specific question, with new questions raised alongside it.

Myths vs. Facts

Common Mistakes to Avoid

1. Reading “safe for the heart” as “no risks at all.” The MACE finding is reassuring; the side-effect findings are real.
2. Applying the results to performance or muscle-building use. That population was not studied.
3. Starting testosterone without a confirmed deficiency. It should be prescribed for a real, tested indication.
4. Ignoring a personal history of blood clots. Raise it specifically with your doctor.
5. Skipping monitoring. Blood counts, heart rhythm, and kidney function warrant follow-up.
6. Treating this one trial as the final word. Several findings still need confirmation.

When to See a Doctor

Discuss testosterone with a doctor if you:

• Have symptoms of low testosterone, such as persistent low libido, fatigue, low mood, or erectile difficulties, and want them properly assessed
• Are taking testosterone and have not had recent monitoring
• Have a history of blood clots, heart rhythm problems, or kidney disease and take or are considering TRT

Seek urgent care if, while taking testosterone, you experience:

• Chest pain, sudden shortness of breath, or coughing up blood, which can signal a pulmonary embolism
• A fast, irregular, or pounding heartbeat, palpitations, or fainting, which can signal atrial fibrillation
• Swelling, pain, or redness in one leg, which can signal a blood clot
• A sharp drop in urination or severe swelling, which can signal kidney problems

Low testosterone should be diagnosed with both symptoms and blood tests, and treatment should always be medically supervised. Testosterone is not a general wellness supplement.

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Action Steps

1. If you have symptoms of low testosterone, ask for a proper evaluation, including blood tests.
2. Do not self-treat or source testosterone outside medical care.
3. If you are considering TRT, discuss the TRAVERSE findings, both the reassurance and the risks, with your doctor.
4. Disclose any history of blood clots, irregular heart rhythm, or kidney problems.
5. If you take TRT, keep up with recommended monitoring.
6. Learn the warning signs of clots and irregular heart rhythm.
7. Remember these findings apply to replacement therapy, not performance use.

Frequently Asked Questions

Does testosterone therapy cause heart attacks?

The TRAVERSE trial found that testosterone replacement therapy did not increase the rate of heart attacks, strokes, or cardiovascular deaths in men with genuine testosterone deficiency and heart risk, compared with placebo. This was reassuring, though the study did find other adverse effects.

So is testosterone completely safe for the heart?

Not entirely. It did not raise major cardiac events, but the study found more atrial fibrillation, pulmonary embolism, and acute kidney injury in the testosterone group. “Reassuring on heart attacks and strokes, but not risk-free” is the accurate summary.

Who did the study apply to?

Men aged 45 to 80 with low testosterone, symptoms of deficiency, and existing or high risk of heart disease. It does not apply to healthy men, performance or muscle-building use, high non-medical doses, or women.

Should I be worried about atrial fibrillation on testosterone?

The trial found a modest but significant increase in atrial fibrillation. It is worth discussing with your doctor, especially if you have palpitations or other risk factors, and it is a reason for monitoring rather than automatic avoidance.

Does this mean testosterone is good for my heart?

No. The study tested safety, not benefit. It does not show that testosterone improves heart health, only that it did not increase major cardiac events in the men studied.

Can I take testosterone for energy or muscle if my levels are normal?

The TRAVERSE findings do not support that. The study was in men with genuine deficiency. Taking testosterone without a medical indication, or at high doses, carries risks that were not studied here.

What should I tell my doctor before starting TRT?

Mention any history of blood clots, irregular heart rhythm, kidney disease, or cardiovascular disease, and make sure your low testosterone is confirmed by symptoms and blood tests before starting.

Key Takeaways

• The TRAVERSE trial was a large, rigorous study designed to answer whether testosterone replacement therapy harms the heart.
• In men with genuine testosterone deficiency and heart risk, TRT did not increase major adverse cardiac events (heart attack, stroke, cardiovascular death).
• However, it was associated with more atrial fibrillation, pulmonary embolism, and acute kidney injury, findings researchers called unexpected.
• The results apply to medically indicated replacement therapy, not to healthy men, performance use, or high non-medical doses.
• A history of blood clots is a specific reason for caution.
• The trial tested safety, not benefit; it does not show testosterone improves heart health.
• Testosterone should be prescribed for a diagnosed deficiency and used with medical monitoring.

The Bottom Line

For years, the question of whether testosterone therapy threatens the heart hung over every prescription. The TRAVERSE study gave the clearest answer yet: for men with genuine, symptomatic testosterone deficiency, replacement therapy does not appear to increase heart attacks, strokes, or cardiovascular deaths. That is real reassurance, and it should ease a worry many men have carried.

But the honest answer keeps its caveats. Testosterone is not a clean bill of health for the heart. The same trial flagged more atrial fibrillation, more blood clots in the lungs, and more kidney injury, and those findings deserve attention rather than dismissal. And the reassurance applies to men who genuinely need the treatment, not to healthy men chasing energy or muscle, for whom the risk picture remains different and far less studied.

If you have symptoms of low testosterone, the sensible path is a proper evaluation and an honest conversation with your doctor, one that weighs both sides of what TRAVERSE found. Used as intended, testosterone therapy now rests on much firmer ground. Used as a shortcut, it does not.

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References

Baillargeon, J., Kuo, Y. F., Westra, J. R., Urban, R. J., & Goodwin, J. S. (2018). Testosterone prescribing in the United States, 2002–2016. JAMA, 320(2), 200–202. https://doi.org/10.1001/jama.2018.7999

Cleveland Clinic. (2026). TRAVERSE study supports cardiovascular safety of testosterone therapy when used as indicated. https://consultqd.clevelandclinic.org/traverse-study-supports-cardiovascular-safety-of-testosterone-therapy-when-used-as-indicated

Corona, G., et al., European Expert Panel for Testosterone Research. (2025). Cardiovascular safety of testosterone therapy: Insights from the TRAVERSE trial and beyond. https://pmc.ncbi.nlm.nih.gov/articles/PMC12670475/

HCPLive. (2026). TRAVERSE trial: No increased cardiovascular risk with testosterone replacement therapy. https://www.hcplive.com/view/traverse-trial-no-increased-cardiovascular-risk-with-testosterone-replacement-therapy

Khera, M., et al., Androgen Society. (2024). Making sense of the TRAVERSE trials. https://www.androgensociety.org/learning-resources/traverse

Lincoff, A. M., Bhasin, S., Flevaris, P., Mitchell, L. M., Basaria, S., Boden, W. E., Cunningham, G. R., Granger, C. B., Khera, M., Thompson, I. M. Jr., et al. (2023). Cardiovascular safety of testosterone-replacement therapy. New England Journal of Medicine, 389(2), 107–117. https://doi.org/10.1056/NEJMoa2215025

Morgentaler, A., et al. (2024). Androgen Society position paper on cardiovascular risk with testosterone therapy. Mayo Clinic Proceedings, 99(11). https://www.mayoclinicproceedings.org/article/S0025-6196(24)00408-7/fulltext

Snyder, P. J., Bauer, D. C., Ellenberg, S. S., Cauley, J. A., Buhr, K. A., Bhasin, S., Miller, M. G., Khan, N. S., Li, X., & Nissen, S. E. (2024). Testosterone treatment and fractures in men with hypogonadism. New England Journal of Medicine, 390(3), 203–211. https://doi.org/10.1056/NEJMoa2308836

U.S. Food and Drug Administration. (2015). FDA drug safety communication: FDA cautions about using testosterone products for low testosterone due to aging. https://www.fda.gov/drugs/drug-safety-and-availability/

Mayo Clinic. (2024). Testosterone therapy: Potential benefits and risks as you age. https://www.mayoclinic.org/healthy-lifestyle/sexual-health/in-depth/testosterone-therapy/art-20045728