TRT and Heart Health: What the TRAVERSE Trial Says About Cardiovascular Risk

For more than a decade, one question hung over testosterone replacement therapy (TRT): does it raise your risk of a heart attack or stroke? In 2014 and 2015, the FDA slapped warning labels on every testosterone product over possible heart risk. Then in 2023, the largest trial ever run on the subject reported its results. The picture changed.

This guide walks through what the TRAVERSE trial actually found, why the old warnings existed, what risks are still real, and how to read all of it if you are on TRT or thinking about starting.

Medical disclaimer: This article is for education only. It is not medical advice. TRT is a prescription therapy, and heart risk is personal. Talk to a licensed physician about your own labs, history, and risk factors before starting, stopping, or changing any treatment.

Quick Answer

• The big trial (TRAVERSE, 5,246 men) found TRT did not raise the rate of major heart events — heart attack, stroke, or cardiovascular death — versus placebo over about 2 years, even in men who already had heart disease or were at high risk (Lincoff et al., NEJM 2023).
• But TRT did raise three specific risks: atrial fibrillation (irregular heartbeat), pulmonary embolism (a blood clot in the lung), and acute kidney injury. These were higher with testosterone than placebo.
• In 2025 the FDA removed the heart-attack/stroke boxed warning from all testosterone products, citing TRAVERSE, but kept and strengthened warnings about blood clots and blood pressure (FDA, 2025).
• The reassurance has limits. TRAVERSE only studied men with diagnosed low testosterone. It does not cover bodybuilder doses, men with normal testosterone, or anyone using TRT to chase performance.

What Was the TRAVERSE Trial, and Why Did It Happen?

TRAVERSE was a large clinical trial built to answer one question: is testosterone therapy safe for the heart?

The trial did not happen by accident. In 2015, the FDA ordered testosterone manufacturers to run a proper safety study. A few earlier reports had hinted that TRT might raise heart risk, but the data were messy and the studies were small. The FDA wanted a real answer. TRAVERSE was that answer.

The name stands for Testosterone Replacement therapy for Assessment of long-term Vascular Events and efficacy Response in hypogonadal men. It was a randomized, double-blind, placebo-controlled trial — the gold standard for testing whether a drug causes harm.

Here is the design at a glance.

Source: Lincoff AM, Bhasin S, et al. NEJM. 2023.

Two things make this trial matter more than anything before it. First, the size. Over 5,000 men is huge for this kind of study. Second, the group studied. These were not young, healthy gym-goers. These were older men who already had heart trouble or were close to it. If TRT were going to hurt anyone's heart, this is the group where you would see it.

Did TRAVERSE Find That TRT Causes Heart Attacks or Strokes?

No. That is the headline finding.

The trial tracked a combined endpoint called MACE — major adverse cardiovascular events. MACE bundles together the outcomes people fear most: death from a heart problem, a non-fatal heart attack, and a non-fatal stroke. The question was whether testosterone caused more of these than a dummy gel.

It did not. The rates were nearly identical, and slightly lower in the testosterone group.

Source: Lincoff AM, et al. NEJM. 2023.

The trial was designed as a "noninferiority" study. In plain terms, the goal was to prove testosterone was no worse than placebo for the heart, within a pre-set safety margin. It cleared that bar. Testosterone was noninferior to placebo for major heart events.

This is why major bodies, including the Cleveland Clinic, described the result as supporting the cardiovascular safety of testosterone therapy when it is used the right way — in men who genuinely have low testosterone.

One number to hold onto: 7.0% versus 7.3%. That tiny gap, in the highest-risk men they could find, is the strongest evidence we have that TRT does not trigger heart attacks or strokes in men who need it.

So TRT Is Totally Safe for the Heart? Not Quite.

Here is where careful reading matters. TRAVERSE cleared testosterone on the big three — heart attack, stroke, cardiac death. But the trial also caught three other problems that showed up more often with testosterone. These are the catch.

Source: Lincoff AM, et al. NEJM. 2023.

Let me unpack each one.

Atrial fibrillation (AFib). This is an irregular, often fast heartbeat. It is not a heart attack, but it is not nothing. AFib raises your long-term risk of stroke and can cause palpitations, fatigue, and shortness of breath. The TRAVERSE researchers said this finding was a surprise — earlier studies had not flagged it.

Pulmonary embolism (PE). This is a blood clot that travels to the lungs. It can be life-threatening. Unlike the AFib signal, this one was not a shock. Blood-clot risk has been on testosterone labels for years, and TRAVERSE simply confirmed it. Testosterone can thicken the blood and raise red blood cell counts, which is part of why clots form.

Acute kidney injury. A sudden drop in kidney function. Like AFib, this was an unexpected signal that had not appeared in older, smaller studies.

The trial authors were direct about the takeaway: testosterone should be used with caution in men who have had a previous blood-clot event. That advice lines up with existing guidance from the Endocrine Society Clinical Practice Guideline.

If you want a fuller breakdown of these and other side effects beyond the heart, our guide on TRT side effects and safety goes deeper.

What Did the FDA Do After TRAVERSE?

The FDA changed the labels. This is the most concrete real-world result of the trial.

Back up to understand the shift. In 2014, the FDA added a warning about blood clots (venous thromboembolism) to testosterone labels. In 2015, it went further and required a warning about possible heart-attack and stroke risk on every testosterone product. For a decade, that heart warning shaped how doctors and patients thought about TRT.

Then TRAVERSE landed. In February 2025, the FDA issued class-wide labeling changes for all testosterone products. Two moves stand out.

Source: FDA. Class-wide labeling changes for testosterone products. 2025.

Read that carefully. The FDA did not declare testosterone risk-free. It removed one warning that the data no longer supported and added another that the data did support. The blood-clot warning stayed. The new blood-pressure warning is a reminder that "heart health" is bigger than just heart attacks — high blood pressure quietly damages the heart and arteries over years.

The lesson: the science moved, and the label moved with it, in both directions.

Who Does TRAVERSE Actually Apply To?

This is the most important and most misunderstood part of the whole story.

TRAVERSE studied a very specific group: middle-aged and older men with medically confirmed low testosterone plus symptoms, who also had or were at high risk for heart disease. The reassuring results apply to men like that. They do not stretch to everyone.

Here is who the trial does not speak for.

This matters because TRT prescribing has exploded, and not all of it follows the rules. The Endocrine Society Clinical Practice Guideline stresses that testosterone should only be prescribed after a proper workup, with ongoing monitoring — yet much real-world prescribing skips those steps. TRAVERSE is reassuring for men who fit the trial. It is not a green light to take testosterone you do not need.

The trial also tells us nothing about super-high "blast and cruise" cycling doses. Those carry their own, separate, and much less studied risks.

If you are not sure whether you actually have low testosterone, start with our guide on low-testosterone symptoms and diagnosis. The diagnosis should always come before the prescription.

What Do the Major Guidelines Say Now?

Two big sets of guidelines shape how doctors handle TRT and the heart in the United States: the Endocrine Society and the American Urological Association (AUA). Both predate the final TRAVERSE results but remain the backbone of careful practice.

Endocrine Society Clinical Practice Guideline (2018). This guideline insists that testosterone be reserved for men with both symptoms and consistently low, confirmed testosterone levels. It warns against prescribing on a single borderline lab or on symptoms alone. It also flags caution in men with recent cardiovascular events (Bhasin S, et al. JCEM. 2018).

AUA Guideline on Testosterone Deficiency (2018, updated since). The urology guideline reaches a similar place: confirm the diagnosis with two low morning readings, counsel men on the cardiovascular evidence, and monitor blood counts and other labs during treatment (Mulhall JP, et al. J Urol. 2018).

The through-line across every guideline is the same. Confirm. Counsel. Monitor. TRAVERSE supports that approach rather than replacing it.

Here is how the timeline of evidence and policy fits together.

Were There Other Surprises in TRAVERSE Beyond the Heart?

Yes. One follow-up analysis deserves a mention because it surprised even the researchers.

For years, doctors assumed testosterone would strengthen bones and cut fracture risk. Older studies had shown it improved bone density. So a TRAVERSE substudy looked at whether men on testosterone broke fewer bones. The result went the wrong way.

Source: Snyder PJ, et al. NEJM. 2024.

Men on testosterone had more fractures, not fewer. The researchers, led by Dr. Peter Snyder, said the reason is unclear and may involve effects on cortical bone. It is a reminder that intuition is not data. Even a therapy that improves a lab number (bone density) can move the outcome that actually matters (broken bones) in an unexpected direction.

This is exactly why large, well-run trials matter. They catch things that smaller studies and reasonable assumptions miss.

How Should You Use This Information If You're On or Considering TRT?

Translate the science into action. Here is a practical way to think about it.

1. Get a real diagnosis first. TRAVERSE only reassures men who actually have low testosterone. That means two separate morning blood tests showing low levels, plus symptoms. See our TRT lab and monitoring guide for what to test and when.

2. Know your clot history. If you have ever had a deep vein thrombosis, a pulmonary embolism, or a clotting disorder, raise it loudly with your doctor. This is the population the TRAVERSE authors singled out for caution.

3. Watch your blood pressure and red blood cell count. Both can rise on testosterone. Both are checkable. Regular monitoring catches problems before they become emergencies.

4. Ask about your heart rhythm. If you have a history of atrial fibrillation or palpitations, the AFib signal in TRAVERSE is worth a frank conversation before starting.

5. Be honest about your dose and goals. TRAVERSE applies to replacement doses, not performance doses. The further you drift from a normal-range replacement, the less the reassuring data apply to you.

Choosing the right provider makes all of this easier. A good clinic confirms the diagnosis, monitors the right labs, and adjusts your dose. Our guide on how to choose a TRT provider walks through what to look for, and you can compare real clinics on our providers directory and side-by-side comparison page. If cost is on your mind, the TRT cost calculator helps you estimate the monthly spend across telehealth, clinic, and insurance routes.

Frequently Asked Questions

Does TRT increase the risk of heart attack or stroke? Based on the TRAVERSE trial — the largest study ever done — TRT did not increase heart attacks, strokes, or cardiovascular death compared to placebo in men with confirmed low testosterone, even high-risk men, over about two years (Lincoff et al., NEJM 2023). The FDA removed the heart-attack/stroke warning from testosterone labels in 2025 as a result.

If heart attacks aren't the worry, what is? TRAVERSE found testosterone raised three other risks versus placebo: atrial fibrillation (irregular heartbeat), pulmonary embolism (a lung blood clot), and acute kidney injury. Blood-clot and blood-pressure warnings remain on testosterone labels. These are the real cardiovascular concerns to monitor.

Does the TRAVERSE result mean TRT is safe for everyone? No. The trial only studied men 45 to 80 with medically confirmed low testosterone. It does not apply to men with normal testosterone, to athletes on high performance doses, or to anyone using TRT without a proper diagnosis. The reassurance is specific to men who genuinely need treatment.

Why did the FDA change the warning labels in 2025? TRAVERSE showed no extra major heart events with testosterone, so the FDA removed the heart-attack/stroke boxed warning. At the same time, it added a warning about increased blood pressure, because monitoring studies showed testosterone can raise it. The blood-clot warning stayed in place (FDA, 2025).

Should I worry about my bones on TRT? Possibly. A TRAVERSE substudy found men on testosterone had slightly more fractures than those on placebo, which surprised researchers who expected the opposite (Snyder et al., NEJM 2024). If you have low bone density or fracture risk, discuss it with your doctor before starting.

Related Guides

• TRT Side Effects & Safety: What the Evidence Says
• Do I Need TRT? Low-Testosterone Symptoms & How It's Diagnosed
• TRT Blood Work: The Labs & Monitoring Schedule
• How to Choose a TRT Provider: Telehealth vs In-Person
• How Much Does TRT Cost?

Sources

1. Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE). New England Journal of Medicine. 2023. PMID 37326322
2. Snyder PJ, Bauer DC, Ellenberg SS, et al. Testosterone Treatment and Fractures in Men with Hypogonadism. New England Journal of Medicine. 2024. PMID 38231621
3. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. JCEM. 2018. PMID 29562364
4. Mulhall JP, Trost LW, Brannigan RE, et al. Evaluation and Management of Testosterone Deficiency: AUA Guideline. Journal of Urology. 2018. PMID 29601923
5. U.S. Food and Drug Administration. FDA Issues Class-Wide Labeling Changes for Testosterone Products. 2025. FDA.gov
6. Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. JCEM. 2018. PMID 29562364
7. Cleveland Clinic ConsultQD. TRAVERSE Study Supports Cardiovascular Safety of Testosterone Therapy When Used as Indicated. ConsultQD
8. TRAVERSE secondary safety findings (atrial fibrillation, pulmonary embolism, acute kidney injury). PubMed search