Androgen decline with aging typically occurs after 50 years, although the fall in testosterone levels can begin as early as 30 years of age. The patient may or may not be symptomatic. Symptoms can range from fatigue to sexual dysfunction. Long-term effects of lowered testosterone can be seen in organ systems including the brain, muscle, adipose tissue, hair, bone, and the cardiovascular system. There is no consensus for androgen replacement as prevention, but there is consensus in the treatment and reversal of symptoms associated with hypogonadism. However, treatment must be carefully monitored. While there are significant benefits in the improvement of symptoms, there are also possible side effects that will be discussed in detail in this article. A careful risk–benefit analysis has to be carried out and treatment must be individualized.