Does TRT raise your risk of a heart attack or stroke?
For many men, probably not. The biggest trial so far, called TRAVERSE, found that testosterone gel did not raise heart attacks, strokes or heart deaths compared with a dummy gel. These were men aged 45 to 80 who already had heart disease or a high risk of it.
But TRT heart risk isn’t zero. The same trial found more irregular heartbeats, kidney injury and clots in the lungs. It’s one of the most important topics in our guide to TRT side effects, and part of what to weigh when starting TRT.
What did the TRAVERSE trial test?
TRAVERSE tested whether testosterone is safe for the heart. It wasn’t testing whether testosterone helps the heart. It ran at 316 sites across the US.
| What | Details |
|---|---|
| Who | 5,246 men aged 45 to 80 with symptoms of low testosterone |
| Testosterone levels | Two fasting results under 300 ng/dL before starting |
| Heart risk | All had heart disease or a high risk of it |
| Treatment | A daily testosterone gel or a dummy gel |
| Target level | Gel adjusted to keep testosterone between 350 and 750 ng/dL |
| Time on treatment | About 22 months on average |
| Time followed | About 33 months on average |
The men were older and heavier than average. Their average age was 63, and their average BMI was 35.
Most had other health problems too. About 69% had diabetes and 93% had high blood pressure, and about 55% already had heart disease.
What did TRAVERSE find?
The main result was reassuring. A heart attack, stroke or heart death happened in 7.0% of men on testosterone and 7.3% on placebo. That’s almost the same.
Some other problems were more common on testosterone, according to the gel’s label:
- Atrial fibrillation: 3.5% on testosterone and 2.4% on placebo. This is an irregular, often fast heartbeat.
- Irregular heartbeats needing treatment: 5.2% and 3.3%.
- Acute kidney injury: 2.3% and 1.5%. This is a sudden drop in how well the kidneys work.
- Clots in the lungs (pulmonary embolism): 0.9% and 0.5%.
- Broken bones: 3.5% and 2.5%.
“No extra heart attacks or strokes, but more irregular heartbeats and clots: TRAVERSE found both.”
Blood pressure rose a little. After 36 months, top blood pressure numbers were 1.5 points higher on testosterone than on placebo.
In plain numbers, the extra risks were small but real. A gap of 3.5% versus 2.4% means roughly one extra case of atrial fibrillation for every 90 men treated for about two years.
What else did TRAVERSE show?
Several smaller reports came from the same trial. They help round out the picture.
- Prostate: high-grade prostate cancer was rare in both groups. It was found in 0.19% of men on testosterone and 0.12% on placebo.
- Anemia: among men who started with anemia, it cleared in 45.0% on testosterone and 33.9% on placebo after a year.
- Sex life: in men with low sex drive, sexual activity and desire improved more on testosterone. Erections didn’t improve more than on placebo.
- Broken bones: testosterone didn’t lower fractures. There were 3.50% on testosterone and 2.46% on placebo.
So testosterone helped some things, made no difference to others and was linked with more of a few problems. That’s a mixed picture, not a clean bill of health.
What doesn’t TRAVERSE tell you?
Every trial has limits, and these matter for how you read it.
- It tested one gel. No injections, pellets or pills were tested. Injections cause bigger rises and falls in testosterone.
- Many men stopped. About 61% stopped their gel or placebo before the end. That makes any difference harder to see.
- Levels were modest. Average testosterone on treatment was about 420 to 440 ng/dL in the first three years.
- It ran for about three years. It can’t tell you about 10 or 20 years of treatment.
- The men were 45 to 80 with heart risk. It tells us less about younger, healthier men.
- Everyone had low testosterone. It says nothing about men with normal levels who use testosterone.
- It checked safety, not benefit. Not being worse than placebo isn’t the same as protecting the heart.
So the honest summary is narrow. One gel, in older men with heart risk, didn’t raise heart attacks or strokes over about two to three years. Whether the same holds for weekly injections over decades is still unknown.
Why did earlier studies warn about heart risk?
The worry started with a few studies about 15 years ago. In 2010 a trial of 209 older men with mobility problems, average age 74, was stopped early.
There were 23 heart-related problems on testosterone and 5 on placebo. But the trial was small and its men had mobility problems and many other health conditions. Its authors said it couldn’t be applied more widely.
Two record studies followed. A study of veterans in 2013 linked testosterone to more deaths, heart attacks and strokes.
In that study, 25.7% of men on testosterone had one of those events within three years, against 19.9% of men not on it. A 2014 insurance study of 55,593 men compared the 90 days after a first prescription with the year before. Heart attacks were about 1.4 times as common after the prescription, and about 2.2 times as common in men aged 65 and over.
Record studies like these can’t prove cause. Men who got testosterone may have differed in other ways.
Still, in 2015 the FDA concluded there was a possible increased heart risk. It required a warning on all testosterone labels.
What changed on testosterone labels?
In 2025 the FDA reviewed TRAVERSE. It removed the boxed-warning language about an increased risk of heart problems, and it added the trial results to every testosterone label.
It also added or updated blood pressure warnings for all products. That followed 24-hour monitoring studies that showed blood pressure rises with every type of testosterone.
In June 2026 the FDA asked makers for more label updates, including prostate wording and the age-related low testosterone limit of use. It said TRAVERSE did not show a new safety signal for heart outcomes. These requests take time, so the wording on your product may lag behind.
Do other studies agree with TRAVERSE?
Mostly, for the short to medium term.
A pooled analysis of 35 smaller trials, with 5,601 men, found no clear difference in heart problems or deaths. In the trials that shared full patient data, heart problems were 7.5% on testosterone and 7.2% on placebo. Deaths were 0.4% and 0.8%.
Those trials lasted months, not years, and the authors noted a lack of long-term data. TRAVERSE on its own is about as large as all of them put together.
One smaller study pointed the other way on a scan. In 138 older men, a year of testosterone gel increased soft plaque in the heart’s arteries more than placebo.
No heart attacks or strokes happened in either group, and the authors said bigger studies were needed. A scan finding isn’t the same as a heart attack.
Should you start TRT if you have heart disease?
That’s a decision for you, your prescriber and often your cardiologist. The Endocrine Society advises against starting testosterone within 6 months of a heart attack or stroke. It also advises against it with uncontrolled heart failure.
The AUA tells clinicians to say that it can’t yet be stated for sure whether testosterone raises or lowers heart risk. It also says low testosterone is itself a risk factor for heart disease. Both guidelines were written before TRAVERSE.
Since TRAVERSE, a European expert panel has said testosterone is safe for the heart when it’s prescribed to the right men and checked regularly. That’s an expert view, not a US guideline, and it still leaves the choice to you and your prescriber.
| Situation | What guidelines say to prescribers |
|---|---|
| Heart attack or stroke in the last 6 months | Don’t start testosterone (Endocrine Society) |
| Uncontrolled heart failure | Don’t start testosterone (Endocrine Society) |
| Stable heart disease | A shared decision; TRAVERSE included many such men |
| Heart risk in general | Counsel that the effect isn’t certain (AUA) |
What if you’ve had a clot or an irregular heartbeat?
Tell your prescriber before you start. The Endocrine Society also advises against starting testosterone in men with thrombophilia, an inherited tendency to form clots. The AUA says there’s no firm evidence that testosterone causes clots in the veins, but TRAVERSE did see more clots in the lungs.
If you already have atrial fibrillation, that’s a question for your prescriber and cardiologist. TRAVERSE found more of it on testosterone, so they may want to watch your heart rhythm more closely.
Which heart checks matter on TRT?
Two things are worth watching.
The first is blood pressure, which testosterone can raise a little. In a 16-week study using 24-hour monitoring, the gel raised blood pressure by about 1.9 over 1.3 points on average. In men already taking blood pressure medicine, the rise was about 3.0 over 2.2.
Many prescribers check blood pressure at visits, and home readings help fill in the gaps between them.
The second is hematocrit, the share of your blood made of red cells. Testosterone raises it, and very high levels make blood thicker. Prescribers check it before starting, at 3 to 6 months and then every year.
If you’re curious how your schedule shapes your testosterone between doses, the testosterone level calculator shows the curve. Big swings are one reason some prescribers adjust schedules, but that’s their call.
Do you need extra heart tests?
Not usually just because you’re on TRT. The monitoring plans in the Endocrine Society and AUA guidelines don’t list routine heart scans or rhythm tests for men without symptoms. Your prescriber may order them if you have symptoms or a heart history, sometimes with a cardiologist.
What helps most is simple: keep your visits, keep your blood tests, and mention new symptoms early. Small changes are easier to deal with when they’re caught early.
When should you call your prescriber or 911?
Call 911 right away for any of these:
- Chest pain or pressure, especially with sweating, nausea or shortness of breath.
- Sudden weakness or numbness on one side of the body, a drooping face or trouble speaking.
- Sudden shortness of breath or chest pain when breathing, which can mean a clot in the lungs.
Call your prescriber soon if you notice a racing, fluttering or irregular heartbeat. Atrial fibrillation can cause these feelings, along with tiredness or dizziness. Also call about a painful, swollen leg, which can mean a clot.
What should you ask your prescriber about heart risk?
- Given my heart history, is TRT a reasonable choice for me?
- Should my cardiologist be involved?
- How often will you check my blood pressure and hematocrit?
- Which symptoms should make me call you?
- Does my type of testosterone change any of this?
How can you keep track of heart-related signs?
Write down your blood pressure readings, any palpitations or breathlessness and the dates of your blood tests. Patterns are easier to see over months than in a single visit.
TRTracker lets you log how you feel next to your injections and lab results. It doesn’t detect heart problems, so anything worrying still goes to your prescriber or 911.