The good news is that testosterone was not shown to cause atherosclerosis — plaque build-up on arterial walls that significantly increases the risk of cardiovascular events.
The bad news is that testosterone did not improve overall sexual function, sexual desire, erectile function, or partner intimacy among men in the study. Authors of the study concluded, “increasing testosterone levels above the lower limit of the normal range in healthy men does not further improve sexual function.”
Conclusions were based on data from about 300 men over 60 years old, half of whom were given testosterone gel and the other half a placebo. After three years, there was no difference in the carotid artery thickness, coronary artery calcium levels, or health-related quality of life.
However, the study had some limitations. It was funded drug-makers who sell testosterone treatments. Three authors disclosed ties to those pharmaceutical companies. The study also did not investigate stroke risks or rule out other causes of cardiovascular events.
For example, testosterone can boost the number of red blood cells, which might thicken the blood and increase the risk of a deadly clot. Testosterone might also loosen existing arterial plaques in the first 30 days of treatment, some studies suggest.
In 2013, a study published by JAMA found a 30% increased risk of heart attack, stroke, and death associated with testosterone. Another study found a doubled risk of heart attack among older men on testosterone therapy.