Testosterone replacement therapy (TRT) is a type of hormone therapy that uses testosterone to treat low testosterone levels in men.
Testosterone is central to the male body. It's responsible for developing and maintaining male characteristics such as muscle mass, facial hair, and a deep voice. Additionally, TRT can improve sexual function, energy levels, and mood. TRT was first used in the 1930s to treat men with hypogonadism, a condition that causes the body to produce very little testosterone.