Decreased libido is a reduction in sex drive. About one in five men have a low sex drive according to Dr. Irwin Goldstein, editor of The Journal of Sexual Medicine.

Possible causes include psychologic factors (such as depression, anxiety, or relationship problems), drugs, and low blood levels of testosterone.

Depending on the cause, your doctor may suggest psychologic counseling, prescribe a different drug, or recommend testosterone supplementation therapy.

A blood test can measure the level of testosterone in the blood. The diagnosis of low testosterone (called hypogonadism) is based both on the man's description of his symptoms and his low blood levels of testosterone.