Testosterone therapy, also known as testosterone replacement therapy (TRT), is a treatment used to address low testosterone levels in men, often due to aging or medical conditions causing hypogonadism. When it comes to cardiovascular patients, the safety of testosterone therapy has been a topic of extensive research and debate. The current understanding is nuanced, balancing potential benefits against risks, with recent studies providing more clarity than ever before.
Testosterone plays a significant role in male health, influencing muscle mass, fat distribution, bone density, mood, and cardiovascular function. Low testosterone levels have been associated with increased risks of metabolic syndrome, cardiovascular disease, and osteoporosis. For men with documented testosterone deficiency—typically defined as consistently low testosterone levels below 300 ng/dL along with symptoms such as fatigue, reduced libido, or muscle weakness—TRT can improve quality of life and some cardiovascular parameters.
The landmark TRAVERSE trial, which involved over 5,000 men with low testosterone and cardiovascular risk factors, found that testosterone therapy did not increase the risk of major cardiovascular events such as heart attacks or strokes compared to placebo. This trial led to the removal of previous FDA cardiovascular warnings on testosterone products in early 2025, marking a significant shift in the perception of TRT safety for men with heart disease risk. The study showed nearly identical rates of cardiac events between the TRT and placebo groups, suggesting that properly prescribed testosterone therapy is not inherently dangerous for cardiovascular patients.
However, TRT is not without potential cardiovascular concerns. One notable effect is its tendency to increase hematocrit—the concentration of red blood cells in the blood. Elevated hematocrit thickens the blood, which can raise blood pressure and increase vascular resistance, potentially straining the heart. Some clinical studies have observed modest increases in systolic blood pressure in men undergoing TRT, especially those with preexisting risk factors such as obesity, sleep apnea, or existing cardiovascular disease. This means that while TRT itself may not directly cause heart attacks, it can contribute to conditions that increase cardiovascular strain if not carefully monitored.
Because of these risks, current guidelines emphasize careful patient selection and ongoing monitoring. Men considering TRT should have confirmed low testosterone levels and symptoms consistent with deficiency. Contraindications include active prostate or breast cancer, elevated prostate-specific antigen (PSA) levels, and uncontrolled heart failure. Once therapy begins, regular follow-ups are essential to monitor blood pressure, hematocrit, and other cardiovascular parameters. Different delivery methods of testosterone—such as topical gels versus injections—may carry varying risk profiles, with topical forms generally providing more stable hormone levels and potentially safer cardiovascular effects.
Beyond direct cardiovascular risks, testosterone therapy’s impact on other heart-related conditions like atrial fibrillation remains unclear, with current evidence not definitively linking TRT to increased risk of arrhythmias or major adverse cardiovascular events. Additionally, recent advances in biomarker research and precision medicine are helping tailor testosterone therapy more safely by identifying individual patient variations in hormone metabolism and cardiovascular risk.
It is also important to consider the context in which testosterone therapy is administered. TRT prescribed and monitored by experienced clinicians, with appropriate dosing and regular laboratory testing, tends to have a safer profile. In contrast, testosterone use through unregulated channels or without medical supervision—such as online pharmacies or bodybuilding contexts—can lead to excessive dosing, lack of monitoring, and increased cardiovascular complications.
In summary, testosterone therapy can be safe for cardiovascular patients when prescribed appropriately to men with confirmed testosterone deficiency and when accompanied by careful monitoring of cardiovascular health. It does not appear to increase the risk of major cardiac events in this population, but it can raise blood pressure and hematocrit, which require vigilance. The evolving landscape of research, including large clinical trials and advances in personalized medicine, continues to refine our understanding and improve the safety of testosterone therapy for men with cardiovascular concerns.
