A physical cause, such as changes in endocrine hormones, must be ruled out. Most often, the causes of low sexual desire will not be revealed by medical or laboratory tests. The single biggest psychological cause of hypoactive sexual desire may be depression. Fatigue is up there, too, and a highly stressful lifestyle can have an impact on sex drive. People who have body image problems may also experience a lack of sexual desire.

Relationship experts report that resentment is a major cause of libido loss, and it strikes men as well as women. Anger at a partner—for being overly critical, for being too dominant or too passive, for ignoring one's needs, for any reason at all—can dampen sexual desire.

Decreased sexual desire is a well-established—and common—side effect of treatment with antidepressant drugs.

Childhood sexual abuse also may inhibit sexual desire later in life.