Testosterone and the Causes of Low Libido

Researchers haven't unraveled the mystery of just how testosterone increases libido. It's normal for a man's sex drive to slowly decline from its peak in his teens and 20s, but libido varies widely between men. What one man might consider a low sex drive, another might not. Also, sex drive changes within each man over time and is affected by stress, sleep, and opportunities for sex. For these reasons, defining what's a "normal" sex drive is next to impossible. Usually, the man himself identifies a lack of sex drive as a problem. Other times, his partner may consider it to be an issue.

Low testosterone symptoms don't always include feeling like you have no sex drive. Some men maintain sexual desire at relatively low testosterone levels. For other men, libido may lag even with normal testosterone levels. Low testosterone is one of the possible causes of low libido, however. If testosterone is lowered far enough, virtually all men will experience some decline in sex drive.

In a large study of men in Massachusetts, about 11% overall said they had a lack of sex drive. The researchers then tested all the men's testosterone levels. About 28% of men with low testosterone had low libido. These men were relatively young, with an average age of 47; older men might have worse sexual symptoms.