A decrease in sex drive can develop both due to medical conditions as well as to psychological or emotional issues. Inhibited sexual desire is a type of sexual dysfunction that affects both men and women. A reduction in sexual desire has been associated with low testosterone levels in men. Likewise, women in the menopausal transition sometimes report a decrease in sex drive. Multiple types of chronic illnesses and chronic pain can also lead to a decrease in sex drive, likely through a combination of physical effects of the disease as well as the psychological stress associated with a chronic illness. Painful intercourse (dyspareunia) can lead to loss of libido in women. Psychological factors that may be associated with low libido include poor body image, anxiety, low self-esteem, stress, poor communication, lack of or breach of trust, and unresolved conflicts. Certain medications, such as some antidepressants, can also cause a reduction in sex drive.
Source: http://www.rxlist.com