Low testosterone, or low T, is a condition in men in which the body does not produce enough of the hormone testosterone. Testosterone helps maintain muscle mass, bone density, and sex drive. If testosterone levels get too low, a variety of symptoms can occur. But it is equally integral to know the symptoms. Here we are discussing them in detail! Symptoms of having low testosterone levels: 1. Low sex drive: This is one of the most common and often earliest signs of low testosterone levels. Men may experience a reduced interest in sex, and find it difficult to become aroused.