For men with confirmed low testosterone, the best current evidence does not show that prescribed TRT increases the risk of heart attack or stroke. TRT can still raise blood pressure slightly, and it has been linked to blood clots and an irregular heart rhythm called atrial fibrillation. That is why screening and regular monitoring are part of safe treatment.
Testosterone labels once included boxed warning language about cardiovascular risk, and the FDA required manufacturers to run a large safety trial, called TRAVERSE. Here is what it found, what it did not answer, and how monitoring addresses each concern.
Can TRT cause heart problems?
In the largest randomized trial to date, TRT did not increase major heart events compared with placebo in men with low testosterone and heart risk. The trial did find higher rates of a few specific problems, covered below.
What the TRAVERSE trial did
The TRAVERSE trial (Lincoff et al., New England Journal of Medicine, 2023) enrolled 5,246 men aged 45 to 80. Every participant had symptoms of low testosterone, two fasting testosterone levels below 300 ng/dL, and either existing heart disease or a high risk of it.
Men were randomly assigned to a daily 1.62% testosterone gel, dosed to keep levels between 350 and 750 ng/dL, or a placebo gel. Researchers tracked heart-related death, nonfatal heart attack and nonfatal stroke.
What it showed
- A major heart event occurred in 7.0% of men on testosterone and 7.3% on placebo.
- Testosterone met the trial’s test for being no worse than placebo (noninferior) for these events.
- The testosterone group had a higher incidence of atrial fibrillation, acute kidney injury and pulmonary embolism (a blood clot in the lungs).
What it did not show
TRAVERSE is reassuring, but its limits matter:
- It did not show that TRT protects the heart. It was designed to rule out an increase in risk, not to prove a benefit.
- It tested one product in one group. It studied a topical gel at doses targeting normal-range levels, in middle-aged and older men with confirmed low testosterone. It does not tell us about injections, higher-than-prescribed doses, younger men, or men with normal testosterone.
- Many men did not stay on treatment for the whole study. Mean treatment lasted 21.7 months, while mean follow-up was 33.0 months.
What the FDA did next
In February 2025, the FDA announced class-wide labeling changes for testosterone products. It added the TRAVERSE results, removed boxed warning language about increased risk of adverse cardiovascular outcomes, and required blood pressure warnings for all testosterone products.
The American Urological Association guideline, written before TRAVERSE, also notes that low testosterone itself is a risk factor for cardiovascular disease.
Can TRT raise blood pressure?
Yes, testosterone can raise blood pressure, usually by a small amount on average. The FDA now requires a blood pressure warning on every testosterone product.
According to the FDA, required 24-hour blood pressure monitoring studies “confirmed an increase in blood pressure with use of all testosterone products, class-wide.” In TRAVERSE, systolic blood pressure rose by an average of 1.0 mm Hg on testosterone and fell by 0.5 mm Hg on placebo, a difference of 1.5 mm Hg (FDA prescribing information, Azmiro, 2025).
A small average change can still matter, because blood pressure increases can raise cardiovascular risk over time. Current labeling advises:
- Measuring blood pressure periodically, especially in men with high blood pressure.
- Not using testosterone in men with uncontrolled hypertension.
Can testosterone therapy cause blood clots?
Testosterone therapy has been linked to a higher risk of blood clots in veins, including deep vein thrombosis and pulmonary embolism. The absolute risk in the major trial was low, but the signal is consistent.
What the evidence shows:
- In TRAVERSE, venous blood clots occurred in 1.7% of men on testosterone versus 1.2% on placebo, and pulmonary embolism in 0.9% versus 0.5%, according to FDA labeling.
- In a large insurance-claims study (Walker et al., JAMA Internal Medicine, 2020) of 39,622 men, testosterone use was associated with roughly double the short-term odds of a venous clot, both in men with and without diagnosed low testosterone. This was an observational study, so it shows an association, not proof of cause.
One reason for the link is red blood cells. Testosterone can raise hematocrit, and FDA labeling notes that an increase in red blood cell mass may increase the risk of clots. The Endocrine Society guideline recommends against starting testosterone in men with elevated hematocrit or thrombophilia (an inherited or acquired tendency to clot).
Heart rhythm and other heart-related concerns
TRAVERSE found more atrial fibrillation on testosterone, and testosterone can cause fluid retention in people with existing heart disease. Both are reasons to share your full history before starting.
According to FDA labeling for the TRAVERSE results:
- Atrial fibrillation occurred in 3.5% of men on testosterone versus 2.4% on placebo.
- Nonfatal arrhythmias needing treatment occurred in 5.2% versus 3.3%.
Labeling also warns that testosterone can cause fluid retention (edema), with or without heart failure, in people with existing heart, kidney or liver disease. The Endocrine Society recommends against starting TRT in men with uncontrolled heart failure or a heart attack or stroke in the last 6 months.
How monitoring addresses each concern
Each of these risks has a matching check, which is why monitoring is not optional. The Endocrine Society recommends a standardized monitoring plan that includes symptoms, side effects, testosterone levels and hematocrit.
| Concern | What monitoring looks like |
|---|---|
| Heart attack and stroke risk | Review of heart history and risk factors before starting; guideline-based exclusions for recent events |
| Blood pressure | Periodic blood pressure checks; no TRT with uncontrolled hypertension |
| Blood clots | Hematocrit checked before starting and during treatment; testosterone paused if it rises |
| Heart rhythm | Reporting palpitations, racing heartbeat or fainting promptly |
| Testosterone dose | Levels checked to stay in the intended range; the AUA suggests every 6 to 12 months |
Your provider decides which tests are right for you. Our guide to TRT monitoring blood tests explains what each one measures.
When to seek care urgently
Call 911 for any symptom that could be a heart attack, stroke or clot in the lungs. Do not wait for your next appointment.
- Chest pain or pressure
- Sudden shortness of breath
- Sudden weakness, numbness, facial drooping or trouble speaking
- Fainting or a racing, irregular heartbeat
- A painful, swollen, warm or red leg (get same-day care)
What an appointment at Hormone Balance Centers looks like
Hormone Balance Centers provides telehealth care for eligible adults in Utah and Idaho by secure video, with evening appointments available and no walk-in office. Care is led by Adam Russell, PA-C, a board-certified Physician Assistant with experience in endocrinology and internal medicine.
- Call or text 385-361-8549.
- Complete labs. Your provider decides which tests are appropriate.
- Meet online to review symptoms, history, labs, risks and goals, including your heart history.
- Receive an individualized care and monitoring plan if treatment is appropriate.
Hormone Balance Centers evaluates the whole clinical picture and provides ongoing monitoring. Learn more about our testosterone replacement therapy care.
Frequently asked questions
Does TRT cause heart attacks?
In the TRAVERSE trial, men with low testosterone and high heart risk had similar rates of heart attack, stroke and heart-related death on testosterone gel and placebo. That finding applies to prescribed treatment in men with confirmed low levels, not to high-dose use.
Can I take TRT if I have high blood pressure?
Possibly, if it is controlled. FDA labeling says testosterone is not recommended for men with uncontrolled hypertension and advises regular blood pressure checks. Your provider will weigh your readings and overall heart risk.
What blood test shows clot risk on TRT?
Hematocrit, the share of your blood made up of red blood cells, is the main lab to watch. Testosterone can raise it, and higher levels may increase clot risk. Labeling directs prescribers to pause testosterone if hematocrit becomes elevated.
Talk to us about your heart and hormones
If you have heart concerns and symptoms of low testosterone, an evaluation and labs are the only way to know whether TRT is appropriate and safe for you. Call or text 385-361-8549, or get started online. Read more about TRT monitoring blood tests.
This article is for education only and is not a diagnosis. Talk with a licensed clinician about your own health.
Sources
- Lincoff AM, et al. Cardiovascular Safety of Testosterone-Replacement Therapy (TRAVERSE). N Engl J Med. 2023;389(2):107-117. https://pubmed.ncbi.nlm.nih.gov/37326322/
- U.S. Food and Drug Administration. FDA issues class-wide labeling changes for testosterone products (02/28/2025). https://www.fda.gov/drugs/drug-safety-and-availability/fda-issues-class-wide-labeling-changes-testosterone-products
- U.S. Food and Drug Administration. Azmiro (testosterone cypionate) injection prescribing information, revised 07/2025. https://www.accessdata.fda.gov/drugsatfda_docs/label/2025/216318s005lbl.pdf
- Walker RF, et al. Association of Testosterone Therapy With Risk of Venous Thromboembolism Among Men With and Without Hypogonadism. JAMA Intern Med. 2020;180(2):190-197. https://pmc.ncbi.nlm.nih.gov/articles/PMC6865248/
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715-1744. https://pubmed.ncbi.nlm.nih.gov/29562364/
- American Urological Association. Evaluation and Management of Testosterone Deficiency: AUA Guideline (2018, validity confirmed 2024). https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline