Does testosterone therapy actually improve sexual function and energy?
Yes, but the effect is modest and specific. In the TRAVERSE Sexual Function Study—a large, placebo-controlled trial nested within the main cardiovascular safety trial—men with low testosterone and low libido who received testosterone gel reported a small but statistically significant increase in sexual activity (about half an extra sexual act per day at 6 and 12 months) compared to those on placebo [4]. They also reported improvements in overall hypogonadal symptoms and sexual desire. However, testosterone did not improve erectile function, meaning it is not a reliable treatment for erectile dysfunction on its own [4].
Testosterone therapy also improved energy levels indirectly by correcting anemia. In the same TRAVERSE trial, men with low testosterone and anemia were significantly more likely to have their anemia resolved with TRT (41% at 6 months vs. 27.5% on placebo), and those improvements in hemoglobin were linked to better energy levels [2]. So, while TRT can boost sexual activity and energy, it is not a universal remedy for all age-related sexual or vitality complaints.
Is testosterone therapy safe for the heart and prostate?
The short answer is yes, for most men, but with some important warnings. The TRAVERSE trial, which enrolled over 5,200 men aged 45–80 with low testosterone and existing heart disease or high risk, found that testosterone gel was noninferior to placebo for major adverse cardiac events (heart attack, stroke, cardiovascular death) over an average of 3 years—meaning it did not increase the risk of these events [1]. This is the strongest evidence to date on cardiovascular safety. However, the trial did find a higher incidence of atrial fibrillation (irregular heartbeat), acute kidney injury, and pulmonary embolism (blood clots in the lungs) in the testosterone group, so the therapy is not without risk [1].
For the prostate, the same trial found no significant increase in high-grade prostate cancer (Gleason score ≥4+3) or other prostate events like acute urinary retention or the need for prostate surgery over about 2 years of treatment [3]. Importantly, men with a PSA over 3.0 ng/mL or severe urinary symptoms were excluded from the trial, so these results apply to men who have been screened and deemed low-risk. A separate small study of men on active surveillance for prostate cancer found that starting testosterone did not cause a significant rise in PSA or clear disease progression over an average of 3.7 years, though the sample was small and lacked a control group [6]. Overall, the evidence suggests that in appropriately selected men, TRT does not increase the risk of heart attack, stroke, or prostate cancer in the short-to-medium term.
Who should consider testosterone therapy, and what are its limits?
Testosterone therapy is most appropriate for men with confirmed low testosterone (two morning levels below 300 ng/dL) and clear symptoms like low libido, fatigue, or unexplained anemia. The evidence from the TRAVERSE trial shows that TRT can improve sexual desire and activity, correct anemia, and does not increase heart attack or stroke risk in men with existing heart disease [1][2][4]. However, it does not improve erectile function, and it carries a small increased risk of atrial fibrillation and blood clots [1][4].
The therapy is not for everyone. Men with a history of prostate cancer, high PSA, or severe urinary symptoms were excluded from the major safety trials, so its safety in those groups is less certain [3]. Additionally, the benefits are modest—the improvement in sexual activity, while statistically significant, amounted to about half an extra sexual act per day [4]. For men without clear symptoms or with borderline testosterone levels, the risks may outweigh the benefits. Finally, the need for hormone replacement after adrenal surgery (a different context) is highly individualized and often temporary, underscoring that hormone therapy is not one-size-fits-all [5].
About These Sources
This answer is built on 6 peer-reviewed studies — published from 2023 to 2025, 2 from 2024 or later, 4 in Q1 journals, collectively cited 544 times — selected as the most relevant from 6 studies that passed quality screening, drawn from 52 papers retrieved from a database of over 500 million.
Sources used in this answer
Cardiovascular Safety of Testosterone-Replacement Therapy
In the largest and most rigorous randomized controlled trial to date (TRAVERSE, n=5,246), testosterone gel was noninferior to placebo for major adverse cardiac events (heart attack, stroke, cardiovascular death) over ~3 years, but was associated with higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism.
Efficacy of Testosterone Replacement Therapy in Correcting Anemia in Men With Hypogonadism
In a nested analysis of the TRAVERSE trial (n=5,204), testosterone therapy corrected anemia in a significantly greater proportion of men than placebo (41% vs. 27.5% at 6 months) and reduced the risk of developing new anemia, with improvements linked to better energy levels.
Prostate Safety Events During Testosterone Replacement Therapy in Men With Hypogonadism
In the same TRAVERSE trial (n=5,204), testosterone therapy did not significantly increase the incidence of high-grade prostate cancer (0.19% vs. 0.12% on placebo) or other prostate events over ~2 years, though PSA levels rose slightly more in the testosterone group.
Effect of Testosterone Replacement Therapy on Sexual Function and Hypogonadal Symptoms in Men with Hypogonadism
In a nested Sexual Function Study (n=1,161 men with low libido), testosterone gel improved sexual activity (by ~0.5 acts/day at 6 and 12 months) and sexual desire compared to placebo, but did not improve erectile function.
Hormone Replacement Therapy after Unilateral Adrenalectomy
In a prospective cohort study of 108 patients after unilateral adrenalectomy, glucocorticoid replacement was needed transiently in 42.6% of patients, with most (82.6%) able to stop by 6 months; persistent adrenal insufficiency occurred only in those with hormonally active tumors.
Testosterone replacement therapy in men on active surveillance for prostate cancer.
In a small retrospective study of 43 men on active surveillance for prostate cancer, testosterone therapy did not cause a statistically significant rise in PSA or clear disease progression over a mean of 44.3 months, though the study lacked a control group.