Adverse effects of testosterone replacement therapy: an update on the evidence and controversy.

Testosterone replacement therapy (TRT) has been used in millions of men worldwide to treat diminished libido and erectile dysfunction, and to improve strength and physical function. The estimated likelihood of adverse effects of long-term TRT is still essentially unknown, as overall high-quality evidence based upon prospective randomized trials to recommend for or against its use in most men with testosterone deficiency (TD) is lacking. Evidence to suggest that TRT increases cardiovascular morbidity and mortality risks is poor, as results vary across study populations and their baseline comorbidities.