The Fear That Keeps Men from Getting Help
You have been dealing with crushing fatigue, disappearing sex drive, and stubborn belly fat for months — maybe years. Your blood work confirms what you already suspected: your testosterone is low. Your doctor mentions TRT. And then you Google it.
Within 30 seconds you find a headline that says testosterone therapy causes heart attacks. Another says it increases stroke risk. A third warns about blood clots. Suddenly the treatment that could change your life feels like a gamble with your cardiovascular system.
This fear is not irrational. It comes from real studies that made real headlines. But those headlines told a partial, often misleading story. The actual science — particularly the landmark TRAVERSE trial that followed 5,246 men for an average of nearly three years — tells a very different one.
If you are a man between 35 and 60 weighing whether testosterone therapy is right for you, this article will walk you through what the research actually says, where the scare came from, what risks genuinely exist, and why proper monitoring makes all the difference.
Where the Heart Scare Started
The idea that TRT might be dangerous for your heart did not come from thin air. It came from a handful of studies in the early 2010s that got enormous media coverage — and then shaped medical practice for over a decade.
The TOM Trial (2010)
The Testosterone in Older Men with Mobility Limitations trial enrolled 209 men over age 65 with significant physical limitations. Many already had heart disease, diabetes, or obesity. The trial was stopped early because more cardiovascular events occurred in the testosterone group compared to placebo.
The problems with this study: the participants were elderly, sick, and in many cases already at high cardiovascular risk. The testosterone doses were higher than typical clinical practice. And the number of actual cardiovascular events was very small — making it statistically fragile. But the damage was done. The headline "testosterone causes heart attacks in older men" spread fast.
The 2013 VA Study
A retrospective study of veterans at VA hospitals found higher rates of heart attack and stroke in men who received testosterone. This study also drew intense criticism. The original analysis contained errors that required a correction after publication. The cohort included men who had just undergone coronary angiography — they were already among the sickest cardiovascular patients in the system. And the study did not actually confirm whether the men were taking their prescribed testosterone or what their levels reached.
The 2014 Finkle Study
Published in PLOS ONE, this insurance-claims analysis suggested that men over 65 who filled a testosterone prescription had a higher rate of heart attack in the 90 days afterward. The study relied on pharmacy records, not clinical data. It could not confirm diagnosis, dosing, adherence, or testosterone levels. And it compared testosterone users to men filling prescriptions for PDE5 inhibitors (ED drugs) — a fundamentally different patient population.
In 2015, the FDA required testosterone products to carry a warning about possible cardiovascular risk. Importantly, the FDA did not conclude that TRT causes heart disease — it said the evidence was inconclusive and that more research was needed. That research would come in the form of the TRAVERSE trial.
Why These Studies Dominated the Narrative
Media coverage amplified the worst-case interpretation of each study. Doctors — reasonably cautious — became reluctant to prescribe testosterone. Patients who might have benefited from therapy chose to suffer with symptoms instead. And a generation of men internalized the message that testosterone therapy was a cardiovascular time bomb.
Meanwhile, the limitations of these studies were well-known in the endocrine research community. Multiple professional societies, including the American Urological Association and the European Academy of Andrology, pushed back against the blanket warnings. But nuanced pushback does not generate the same headlines as "testosterone causes heart attacks."
The TRAVERSE Trial: The Answer the Field Needed
The TRAVERSE trial — short for Testosterone Replacement Therapy for Assessment of long-term Vascular Events and efficacy ResponSE in hypogonadal men — was specifically designed to settle the cardiovascular safety question. Published in the New England Journal of Medicine in 2023, it remains the largest and most rigorous randomized controlled trial of testosterone therapy ever conducted.
Study Design
- 5,246 men aged 45 to 80 with hypogonadism (testosterone below 300 ng/dL) and either existing cardiovascular disease or high cardiovascular risk
- Randomized to either 1.62% testosterone gel or placebo
- Mean treatment duration of 21.7 months with mean follow-up of 33 months
- Primary endpoint: first occurrence of death from cardiovascular causes, nonfatal heart attack, or nonfatal stroke (MACE — major adverse cardiovascular events)
Results
The primary cardiovascular endpoint occurred in 7.0% of the testosterone group and 7.3% of the placebo group. Testosterone therapy was noninferior to placebo for MACE — meaning it did not increase the rate of heart attacks, strokes, or cardiovascular death.
To put that plainly: in a population of men who already had heart disease or were at high risk for it, testosterone therapy did not make things worse.
| Outcome | Testosterone Group | Placebo Group |
|---|---|---|
| MACE (primary endpoint) | 7.0% | 7.3% |
| Nonfatal heart attack | 3.4% | 3.2% |
| Nonfatal stroke | 2.0% | 1.9% |
| Death from CV cause | 1.2% | 1.5% |
| Coronary revascularization | 5.0% | 4.6% |
"In men with hypogonadism who had preexisting or a high risk of cardiovascular disease, testosterone-replacement therapy was noninferior to placebo with respect to the incidence of major adverse cardiac events." — Lincoff AM et al., New England Journal of Medicine, 2023.
Important Nuances
TRAVERSE did find a higher incidence of three specific conditions in the testosterone group: pulmonary embolism (blood clot in the lung), atrial fibrillation (irregular heartbeat), and acute kidney injury. These were secondary findings and the absolute numbers were small, but they are clinically meaningful and underscore why regular monitoring during TRT is essential — not optional.
The trial also confirmed benefits that extended well beyond hormones: improvements in anemia, bone mineral density, and sexual function in the testosterone group.
Subsequent Meta-Analyses
Since TRAVERSE, multiple meta-analyses have pooled data from dozens of randomized controlled trials. A 2025 position statement published in the Journal of Sexual Medicine synthesized these findings and concluded: "There is consensus that testosterone therapy, when prescribed to appropriately selected patients and monitored regularly, is safe from a cardiovascular standpoint."
The scientific community has effectively settled this question. TRT, when properly prescribed and monitored, does not increase overall cardiovascular risk.
What Low Testosterone Actually Does to Your Heart
Here is the part that rarely makes the headlines: low testosterone itself is a cardiovascular risk factor. The fear about TRT has overshadowed a substantial body of evidence showing that untreated hypogonadism is associated with worse heart health, not better.
The Mortality Connection
A 2025 study published in BMC Cardiovascular Disorders followed male patients with cardiovascular disease and found that those with low testosterone had a 48% higher risk of all-cause mortality compared to those with normal levels (HR 1.48, 95% CI 1.08–2.02). This is not a subtle association. Low testosterone in men with heart disease is an independent predictor of dying sooner.
This finding is consistent with earlier large cohort studies:
- A Swiss study found that approximately 40% of men with acute coronary syndromes had low testosterone, and those men had higher one-year mortality
- A Greek cohort showed that low T was associated with higher five-year risk of cardiovascular death in men with stable coronary heart disease
- A longitudinal study of 1,470 men found that testosterone replacement was associated with decreased all-cause mortality compared to men whose levels were not normalized
How Low T Damages Your Cardiovascular System
Low testosterone does not just correlate with cardiovascular problems — it contributes to the metabolic profile that drives them:
- Visceral fat accumulation: Low T promotes the storage of deep abdominal fat, which produces inflammatory cytokines and is a major driver of heart disease. If you have been unable to lose weight despite your best efforts, your testosterone level may be part of the reason.
- Insulin resistance: Testosterone improves insulin sensitivity. Low levels are associated with higher fasting glucose, higher insulin, and increased risk of type 2 diabetes — all independent cardiovascular risk factors.
- Unfavorable lipid profile: Men with low T tend to have higher triglycerides, higher total cholesterol, and lower HDL (the protective cholesterol). Multiple large population studies including the Tromsø study and the Rancho Bernardo study have confirmed a positive correlation between testosterone and HDL.
- Chronic inflammation: Testosterone has anti-inflammatory properties. It suppresses pro-inflammatory cytokines like TNF-α, IL-6, and IL-1β while supporting adiponectin — a protective hormone that decreases with visceral fat accumulation. Low testosterone means a more inflammatory internal environment.
- Endothelial dysfunction: Low T is associated with impaired function of the cells lining your blood vessels, which is an early marker of atherosclerosis.
For years, the medical establishment worried that treating low testosterone might cause heart disease. The evidence increasingly suggests the opposite: leaving low testosterone untreated may contribute to cardiovascular risk through metabolic syndrome, inflammation, and unfavorable body composition. The fear of treatment may have been more dangerous than the treatment itself.
How TRT Affects Blood Pressure, Cholesterol, and Inflammation
Understanding how testosterone therapy affects specific cardiovascular markers helps separate fact from fear.
Blood Pressure
Testosterone has complex effects on blood pressure. Short-term, it can cause mild fluid retention through its effects on sodium and water balance, which may temporarily increase blood pressure in some men. Long-term, however, testosterone's effects on body composition (less fat, more muscle), insulin sensitivity, and vascular function tend to be blood-pressure neutral or mildly favorable.
In the TRAVERSE trial, there was no significant difference in blood pressure between the testosterone and placebo groups. Clinical monitoring of blood pressure during TRT is still recommended, particularly in the first few months.
Cholesterol and Lipids
TRT's effects on cholesterol are among the most debated topics in the field. Here is what the evidence shows:
- Total cholesterol: Generally decreases modestly with TRT
- LDL cholesterol: Mixed results — some studies show slight increases, others show no change
- HDL cholesterol: Tends to decrease slightly with exogenous testosterone, particularly with supraphysiological doses. This was one of the original concerns about TRT's cardiovascular safety
- Triglycerides: Generally decrease with TRT, particularly in men with metabolic syndrome
The HDL decrease has received outsized attention. But the clinical significance of this modest reduction is unclear, especially when weighed against improvements in insulin sensitivity, body composition, and inflammatory markers. A 2015 review in Current Opinion in Endocrinology, Diabetes and Obesity concluded that the lipid changes from TRT "do not substantiate conclusions assigning a causal role for TRT in the development of cardiovascular morbidity."
Inflammation
Testosterone is fundamentally anti-inflammatory. A systematic review in the Journal of Clinical Endocrinology & Metabolism confirmed that testosterone therapy reduces C-reactive protein (CRP), TNF-α, and IL-6 — three key inflammatory markers associated with cardiovascular disease. Testosterone also positively correlates with adiponectin, a protective adipokine that decreases with visceral obesity.
For men dealing with chronic low-grade inflammation — often driven by high cortisol, poor sleep, and excess visceral fat — restoring testosterone to healthy levels can help break the inflammatory cycle that feeds cardiovascular risk.
Key Studies at a Glance
The research on testosterone and cardiovascular risk spans decades. Here are the studies that matter most — and what they actually found.
| Study | Year | Size | Key Finding |
|---|---|---|---|
| TOM Trial | 2010 | 209 men | More CV events in testosterone group — but elderly, sick population with high-dose protocol |
| VA Retrospective | 2013 | 8,709 men | Higher CV events with TRT — later corrected for errors; population was post-angiography |
| Finkle (PLOS ONE) | 2014 | 55,593 Rx fills | Higher MI rate post-prescription — insurance claims data, no clinical verification |
| Corona Meta-Analysis | 2014 | 75 RCTs | No association between TRT and cardiovascular events |
| TRAVERSE Trial | 2023 | 5,246 men | TRT noninferior to placebo for MACE in high-risk men |
| Corona Updated Meta | 2024 | 106 RCTs | No increased overall CV risk with TRT; reaffirmed safety |
| BMC CV Disorders | 2025 | Cohort | Low T associated with 48% higher all-cause mortality in men with CVD |
The studies that raised alarms were small, retrospective, or involved populations that do not reflect the typical TRT candidate. The largest and most rigorous evidence — TRAVERSE and the pooled meta-analyses — consistently shows that properly monitored TRT does not increase overall cardiovascular risk.
Real Risks to Monitor During TRT
Saying TRT does not increase overall cardiovascular risk is not the same as saying it has zero risk. There are specific, manageable risks that require monitoring — and they are the reason why TRT should always be prescribed by a knowledgeable provider with a proper follow-up protocol.
Hematocrit and Polycythemia
Testosterone stimulates red blood cell production (erythropoiesis). This is actually one of its benefits — TRT effectively treats anemia associated with hypogonadism, as confirmed by TRAVERSE. But too many red blood cells thicken your blood, increasing the risk of blood clots, stroke, and pulmonary embolism.
This is called polycythemia, and it is the most common reason men need their TRT dose adjusted. A hematocrit level above 54% is a clinical threshold that typically requires intervention — dose reduction, more frequent smaller dosing, or therapeutic phlebotomy (blood donation).
Blood Clots (Venous Thromboembolism)
The TRAVERSE trial did find a slightly higher rate of pulmonary embolism in the testosterone group. While the absolute numbers were small, blood clot risk is real and is likely related to the hematocrit-thickening effect described above. Men with a personal or family history of blood clots should discuss this risk carefully with their provider before starting TRT.
Atrial Fibrillation
TRAVERSE also noted a slightly higher incidence of atrial fibrillation (AFib) in the testosterone group. The mechanism is not fully understood — testosterone may affect cardiac ion channels or atrial remodeling. This is another reason that men with a history of heart rhythm problems should have closer cardiac monitoring if they start TRT.
Fluid Retention
Testosterone promotes sodium and water retention, which can temporarily increase blood volume and blood pressure. This is usually mild and manageable, but it can be clinically significant in men with pre-existing heart failure or kidney disease.
Estradiol Conversion
Testosterone converts to estradiol through the aromatase enzyme. Elevated estradiol can promote fluid retention, raise blood pressure, and contribute to cardiovascular symptoms. Managing estradiol on TRT is a key part of cardiovascular risk management.
Who Needs Extra Caution
TRT is not equally appropriate for every man. The following conditions warrant more careful evaluation and closer monitoring — not necessarily avoidance of TRT, but a more cautious approach:
- Recent heart attack or stroke (within 6 months): Most guidelines recommend waiting and stabilizing cardiovascular status before starting TRT
- Uncontrolled heart failure: Fluid retention from testosterone can worsen symptoms
- Hematocrit already elevated (>50%): Adding testosterone will likely push hematocrit higher
- History of blood clots: The modest increase in VTE risk is more clinically relevant in men with prior events
- Untreated severe sleep apnea: Sleep apnea independently raises hematocrit and cardiovascular risk. TRT can worsen untreated sleep apnea. Get your sleep apnea evaluated and treated first
- Uncontrolled hypertension: Stabilize blood pressure before adding a therapy that may cause mild fluid retention
None of these are absolute contraindications. They are situations where the benefit-risk discussion requires more data, more caution, and more frequent monitoring.
Why Regular Blood Work Is the Real Safety Net
The consistent message from every guideline, every professional society, and every expert in the field is the same: testosterone therapy is safe when monitored properly. The key word is monitored.
Proper TRT monitoring includes:
| Marker | Why It Matters | Frequency |
|---|---|---|
| Total testosterone | Confirms you are in therapeutic range (not too high, not still low) | 6–8 weeks after start, then every 6 months |
| Free testosterone | Measures the bioactive fraction your body actually uses | Same schedule |
| Hematocrit / CBC | Catches polycythemia before it becomes dangerous | 3 months, 6 months, then every 6 months |
| Estradiol | Detects excess aromatization causing fluid retention or symptoms | 6–8 weeks, then every 6 months |
| Lipid panel | Monitors cholesterol and triglyceride changes | Baseline and annually |
| PSA | Screens for prostate changes (TRT and prostate guide) | Baseline, 3 months, then annually |
| Blood pressure | Catches fluid-retention-related hypertension | Every visit |
| Metabolic panel | Kidney and liver function monitoring | Baseline and annually |
The cardiovascular safety of TRT depends on proper patient selection, appropriate dosing, and consistent follow-up blood work. Clinics that write a prescription and never check back are not practicing safe medicine. Heyday's protocol includes regular lab monitoring and clinical review — because the data only protects you if someone is actually checking it. (See the full blood work guide.)
The Bottom Line
The fear that TRT causes heart attacks was driven by small, flawed studies that were amplified by headlines and overapplied to clinical practice. The best evidence we have — the TRAVERSE trial, multiple meta-analyses, and 2024–2025 expert consensus statements — consistently shows that testosterone therapy does not increase overall cardiovascular risk in properly selected and monitored men.
What the evidence does show is equally important:
- Low testosterone itself is a cardiovascular risk factor. Men with untreated hypogonadism have higher rates of metabolic syndrome, insulin resistance, unfavorable lipid profiles, chronic inflammation, and mortality.
- TRT has real but manageable risks — primarily related to hematocrit elevation, blood clots, and atrial fibrillation. These are caught and managed through regular blood work.
- Monitoring is the safety net. The difference between safe TRT and risky TRT is not the testosterone itself — it is whether anyone is checking your hematocrit, estradiol, lipids, and blood pressure regularly.
If you have been avoiding TRT because of heart concerns, the data should be reassuring. If you are already on TRT, the data should motivate you to stay on top of your labs. And if you are not sure where you stand, the first step is always the same: get your levels tested and work with a provider who takes monitoring as seriously as the prescription.