Few topics in men’s health have generated more confusion than the relationship between testosterone and cardiovascular health. For decades, conventional wisdom held that testosterone was bad for the heart — a view rooted partly in the cardiovascular damage caused by supraphysiological doses of anabolic steroids, and partly in the observation that men have higher rates of heart disease than premenopausal women. More recent and more rigorous research has substantially complicated that picture, and in some respects reversed it.
The current evidence — taken as a whole — suggests that low testosterone is associated with increased cardiovascular risk, and that restoring testosterone to normal physiological levels in genuinely deficient men is not the cardiovascular threat it was once assumed to be. That’s a significant shift from the position many physicians held even a decade ago, and it has meaningful implications for how men with low testosterone should think about the cardiac dimension of hormonal health.
This topic deserves an honest treatment because the research is genuinely complex, the history of the field includes important cautionary episodes, and the clinical stakes are high. What follows is a careful account of what the evidence shows, where it remains uncertain, and what the practical implications are for men navigating this question.
How Testosterone Influences Cardiovascular Function
Testosterone has multiple direct and indirect effects on the cardiovascular system, and understanding them helps explain why the relationship between testosterone levels and heart health isn’t simple in either direction.
Vasodilation and Coronary Blood Flow
Testosterone has direct vasodilatory effects on blood vessels — it relaxes vascular smooth muscle and promotes endothelial function, the health of the cells lining blood vessel walls. Studies have found that testosterone administration produces acute coronary vasodilation in men with coronary artery disease, and that men with low testosterone show impaired endothelial function that improves with testosterone restoration. These findings suggest a direct, beneficial effect of testosterone on vascular tone and blood flow that is at odds with the view of testosterone as cardiovascular threat.
Testosterone also stimulates the production of nitric oxide — the primary signaling molecule through which blood vessels dilate — in endothelial cells. Nitric oxide bioavailability is a key determinant of vascular health and is reduced in men with atherosclerosis and cardiovascular disease. Low testosterone is associated with reduced nitric oxide production, and testosterone restoration has been found to improve it in some studies.
Effects on Body Composition and Metabolic Risk
Much of testosterone’s cardiovascular relevance operates through its effects on body composition, insulin sensitivity, and metabolic health. Testosterone promotes lean muscle mass and reduces visceral fat accumulation. Both of these effects are directly cardiovascular relevant: excess visceral fat drives insulin resistance, dyslipidemia, inflammation, and hypertension — the cluster of factors that constitute metabolic syndrome and substantially elevate cardiovascular risk.
Men with low testosterone have higher rates of metabolic syndrome, insulin resistance, and type 2 diabetes than hormonally normal men at equivalent ages and body weights. These metabolic risk factors contribute to cardiovascular disease through well-established pathways. The cardiovascular risk associated with low testosterone may be substantially mediated through these metabolic effects rather than through direct cardiac mechanisms — which has practical implications for how to address it.
Effects on Red Blood Cell Production
Testosterone stimulates erythropoiesis — the production of red blood cells — through effects on erythropoietin signaling. This effect is relevant to cardiovascular health in both directions. In men with low testosterone and anemia, testosterone restoration can improve red blood cell count and oxygen-carrying capacity, with potential benefits for cardiac function and exercise tolerance. In men on TRT, however, testosterone can elevate hematocrit (the proportion of blood volume occupied by red blood cells) to levels that increase blood viscosity and potentially elevate the risk of thrombotic events — blood clots, deep vein thrombosis, pulmonary embolism, and stroke. Elevated hematocrit is one of the cardiovascular side effects most consistently associated with TRT that requires active monitoring. Our article on monitoring your health on TRT covers this and other surveillance requirements in detail.
Lipid Effects
Testosterone’s effects on lipid profiles are more nuanced than a simple beneficial or harmful categorization allows. Testosterone tends to modestly reduce HDL cholesterol — the fraction conventionally associated with cardiovascular protection — which contributed to historical concerns about its cardiac safety. However, the clinical significance of this HDL reduction appears to be modest compared to the improvements in other cardiovascular risk factors: reduced visceral fat, improved insulin sensitivity, and improved endothelial function. Triglycerides, which are a more significant cardiovascular risk marker than HDL in many contexts, tend to decrease with testosterone normalization in hypogonadal men. The net lipid effect of bringing testosterone from deficient to normal is generally neutral to modestly favorable in well-conducted studies.
What Epidemiological Research Shows
Large observational studies examining the relationship between testosterone levels and cardiovascular outcomes in men have produced fairly consistent findings that challenge the testosterone-as-cardiac-risk narrative.
Low Testosterone and Cardiovascular Risk
Multiple large epidemiological studies have found that men with lower testosterone levels have higher rates of cardiovascular disease, cardiovascular events, and cardiovascular mortality than men with higher testosterone. A meta-analysis published in the European Heart Journal synthesizing data from multiple cohort studies found that low testosterone was associated with a significantly increased risk of cardiovascular disease and all-cause mortality, independent of conventional cardiovascular risk factors. Similar findings have emerged from studies examining testosterone and heart failure, testosterone and coronary artery disease prevalence, and testosterone and overall mortality.
These associations don’t prove that low testosterone causes cardiovascular disease — low testosterone and cardiovascular disease may share common upstream causes including poor lifestyle, metabolic dysfunction, and inflammation. But the consistency of the association across multiple study designs and populations is difficult to explain as pure coincidence and provides the basis for hypothesizing that hormonal deficiency is a genuine cardiovascular risk factor in men.
The Confounded History of TRT and Cardiac Safety
The cardiovascular safety of testosterone replacement therapy has had a turbulent research history. A 2010 trial published in NEJM was stopped early after finding more cardiovascular events in the testosterone arm than the placebo arm in a population of older men with mobility limitations and high cardiovascular risk. This trial generated significant concern and regulatory caution, despite its recognized methodological limitations — including a small sample size, a high-risk population, and an unusually high event rate in the control group.
Subsequent larger trials and meta-analyses produced more reassuring findings. Most systematic reviews of randomized controlled trials have not found significantly increased cardiovascular event rates with testosterone treatment in men without pre-existing severe cardiac disease. The cardiovascular safety picture shifted most substantially with the publication of the TRAVERSE trial in 2023 — a large, pre-specified cardiovascular safety study of testosterone treatment in middle-aged men with hypogonadism and elevated cardiovascular risk. TRAVERSE found that testosterone treatment was non-inferior to placebo for major adverse cardiovascular events, substantially addressing the cardiovascular safety question for the population studied, while also noting higher rates of atrial fibrillation, pulmonary embolism, and deep vein thrombosis in the testosterone arm.
What TRAVERSE and Recent Research Mean in Practice
The TRAVERSE trial findings are worth unpacking carefully because they resolve some questions while raising others. The primary finding — that testosterone treatment in hypogonadal men with elevated cardiovascular risk did not increase the rate of major adverse cardiovascular events (heart attack, stroke, cardiovascular death) — was the most important question the field needed answered, and the answer was reassuring. The finding of elevated rates of atrial fibrillation and venous thromboembolism in the testosterone arm, while not translating into overall cardiovascular mortality differences in the trial, are signals that warrant attention in clinical practice, particularly for men with pre-existing arrhythmia history or elevated thrombotic risk.
The practical implication is that TRT in appropriately selected hypogonadal men is not the cardiac catastrophe that early cautionary research suggested, but it’s also not without cardiovascular considerations that require individualized clinical evaluation.
Testosterone, Heart Failure, and Cardiac Function
One area where testosterone’s cardiovascular effects are consistently positive in the research is heart failure. Multiple studies have found that men with heart failure have disproportionately high rates of testosterone deficiency, and that testosterone treatment in heart failure patients with low testosterone improves exercise capacity, functional status, and quality of life. A meta-analysis specifically examining testosterone in heart failure found significant improvements in exercise tolerance — measured by six-minute walk distance — and in several markers of cardiac function.
This is an area where the research is unusually consistent and the mechanistic rationale is clear: testosterone improves skeletal muscle function and reduces inflammatory markers, both of which contribute to the exercise limitation and systemic dysfunction characteristic of heart failure. The cardiac safety of testosterone in this context, when carefully monitored, appears reasonable based on current evidence, though this remains an area of ongoing research and these patients require specialist oversight.
What Men With Cardiovascular Risk Should Consider
For men with established cardiovascular disease or significant cardiovascular risk factors who also have low testosterone, the decision about testosterone treatment is a genuinely complex clinical risk-benefit assessment rather than a simple yes or no. Several considerations are relevant.
The cardiovascular risks of untreated low testosterone — including the metabolic effects, the association with worse cardiac outcomes, and the quality-of-life impairments that affect adherence to cardiac rehabilitation and healthy behaviors — are real and should be weighed alongside the risks of treatment. A man with low testosterone who is deconditioned, insulin-resistant, and poorly motivated to exercise faces cardiovascular risks that testosterone treatment might help address through body composition and energy improvements.
The cardiovascular risks specifically associated with TRT — elevated hematocrit, potential effects on atrial fibrillation risk and venous thromboembolism — are manageable with appropriate monitoring and dose adjustment but require active surveillance rather than passive assumption of safety. Regular monitoring of hematocrit, blood pressure, and symptoms is standard of care for men on TRT, and it’s particularly important in men with pre-existing cardiovascular conditions.
Men with significant cardiovascular disease considering TRT should have this conversation with both their cardiologist and the prescribing physician, with explicit attention to the specific cardiac conditions involved, the severity of testosterone deficiency, and the monitoring plan. Our article on who is a good candidate for TRT discusses how cardiovascular history factors into the candidacy assessment.
Questions Men Ask About Testosterone and Heart Health
Does testosterone cause heart attacks?
At physiological replacement doses in men with genuinely low testosterone, the current evidence does not support a meaningful increase in heart attack risk. The TRAVERSE trial — the largest cardiovascular safety study of TRT conducted — found no significant increase in heart attack or stroke rates compared to placebo in hypogonadal men over a median follow-up period of approximately three years. Earlier concerns were partly based on anabolic steroid research (involving supraphysiological doses) and a small, methodologically limited trial in a very high-risk population. The picture has shifted considerably with better evidence, though cardiovascular monitoring during TRT remains appropriate.
If low testosterone is associated with heart disease, why were doctors worried about TRT for so long?
Several reasons, not all of them unreasonable. Much of the early concern was extrapolated from the known cardiovascular harms of anabolic steroids at supraphysiological doses — a different situation from replacement therapy, but understandably concerning before the distinction was well studied. A 2010 clinical trial that found higher cardiovascular event rates in testosterone-treated men generated regulatory action and clinical caution that persisted for years. And the observation that men have higher cardiovascular risk than premenopausal women — while likely reflecting many factors beyond testosterone — made the hormone a natural focus of suspicion. The current evidence base is substantially better than it was ten years ago, and clinical understanding has evolved accordingly.
Should I be worried about testosterone and blood clots?
Venous thromboembolism — deep vein thrombosis and pulmonary embolism — was identified as a signal in the TRAVERSE trial, with a modestly higher rate in the testosterone arm. The absolute risk increase was small, but it’s a clinically relevant consideration for men with pre-existing thrombotic risk factors: prior DVT or PE, thrombophilia, prolonged immobility, or other hypercoagulable conditions. Testosterone’s effect on hematocrit — elevating red blood cell concentration and blood viscosity — is one plausible mechanism. Men with known thrombotic risk factors should discuss this specifically with their prescribing physician before initiating TRT, and hematocrit monitoring during treatment is standard practice for this reason.
Does exercise reduce cardiovascular risk in men with low testosterone?
Yes, substantially — through mechanisms that partially overlap with testosterone’s effects and through independent cardiovascular pathways. Exercise reduces visceral fat, improves insulin sensitivity, lowers blood pressure, improves endothelial function, and reduces inflammatory markers — all of which benefit cardiovascular health regardless of testosterone status. In men with low testosterone, exercise also directly stimulates testosterone production, which may further benefit the cardiovascular risk picture through the metabolic mechanisms discussed above. The combination of testosterone optimization and consistent exercise likely produces better cardiovascular outcomes than either alone, and exercise is genuinely important for cardiovascular health in this population independent of its hormonal effects. Our article on the best exercises for boosting testosterone naturally covers the training approach most relevant to this goal.
Can improving testosterone levels through lifestyle changes rather than TRT protect my heart?
The cardiovascular benefits of testosterone appear to be associated with adequate hormone levels rather than the method of achieving them. Lifestyle-driven testosterone improvement — through fat loss, resistance training, sleep optimization, and stress management — produces many of the same metabolic improvements (reduced visceral fat, improved insulin sensitivity, reduced inflammation) that are thought to mediate testosterone’s cardiovascular benefits. For men with moderate testosterone deficiency driven by lifestyle factors, optimizing those factors addresses both the hormonal and cardiovascular dimensions simultaneously. Our articles on losing weight and testosterone and the worst habits for testosterone cover the lifestyle changes with the most impact.
My cardiologist said testosterone is bad for the heart. Is that still the standard advice?
Medical guidance on this question has evolved substantially in recent years, and some cardiologists — particularly those who trained before the most recent evidence base developed — may hold positions that are somewhat behind the current literature. The TRAVERSE trial, published in 2023, specifically addressed cardiovascular safety in a high-risk population and produced findings that led to significant updates in clinical thinking. If your cardiologist has significant concerns, a direct conversation about the TRAVERSE findings and the current evidence is appropriate — or a second opinion from a cardiologist or endocrinologist more familiar with the recent literature on testosterone and cardiovascular outcomes.