Loss of libido is a loss of sexual urges and thoughts and/or diminished desire to engage in sexual activity. A dwindling sex drive can be due to several factors and it can vary from one person to the next. Also, there are physical, psychological and relationship issues to consider when evaluating decreased libido.
Some major physical causes of low libido include: hormonal changes, illness, poor nutrition, lack of sleep, lack of exercise, obesity, pain, excessive alcohol, or recreational drug use. Medications such as antidepressants, blood pressure medication, and birth control pills can also interfere with sexual interest.
Psychological causes such as stress, fatigue, low self-esteem, body image concerns, mood swings, depression, and anxiety can all reduce interest in sex, as can relationship issues like decreased availability of a partner, lack of communication between partners, or major life changes. Hormonal imbalance can be a major cause of loss of libido for many men and women. Although low libido is most commonly experienced in perimenopause, menopause, and andropause between the ages of 40 and 55, hormone-related decline in sex drive can occur at younger ages as well. An imbalance of estrogen, progesterone and testosterone levels can lead to a reduction of sexual drive and energy in women. Loss of libido is well known to occur in women who have had total hysterectomies (including removal of the ovaries) because of the large declines in sex hormones.
Properly balanced hormones is one key to maintaining a healthy libido. Both estrogen excess and deficiency have an influence on female libido. Proper amounts of estrogen help maintain sexual interest and keep vaginal tissue healthy. When estrogen supply is low, the vulva and vagina develop thinning, tightening, dryness, and atrophy (a decrease in muscle mass). These changes can cause irritation, soreness, itching, and severe pain during sex, as well as urinary frequency and urgency. Too much estrogen (estrogen dominance) can also cause a loss of interest in sex. Low levels of progesterone can result in estrogen dominance causing heavy periods, depression, fibrocystic breasts, water retention and fatigue, all of which can interfere with sexual desire.
Testosterone in women is also fundamental to sex drive as it influences interest, arousal, sexual response, lubrication, and orgasm. As a result, anything that diminishes testosterone may result in a lack of libido, including too much estrogen. Excessive or chronic stress may also cause a hormonal imbalance that can result in low libido. During periods of stress, progesterone, which is the precursor molecule to testosterone, is converted into cortisol instead of sex hormones. Eventually, this results in low testosterone and reduced libido.
As with women, loss of desire in men also depends upon physical, psychological and relationship variables. In addition, as men age their sex drive tends to decrease, in many instances due to hormonal changes and imbalance. Since male libido is directly influenced by testosterone levels, when testosterone starts to diminish, the result is a dwindling libido. The brain has the largest concentration of testosterone receptors in the body and the sex drive is a function of testosterone stimulating nerve endings in the brain. Low testosterone results in reduced stimulation of nerves in the brain which leads to reduced sexual desire and erectile dysfunction. Erectile dysfunction (impotence) and loss of libido are two separate things; however, men who experience impotence commonly experience a decrease in libido as well.
Anything that increases stress can cause decreased libido because the body reacts to stress by releasing cortisol. Cortisol decreases testosterone hence libido suffers. High estrogen levels in men can reduce sexual appetite, lead to erectile difficulties and produce breast enlargement.
Other hormones which can influence libido in men and women include DHEA and thyroid. Since DHEA is the precursor to testosterone, inadequate DHEA concentrations in the body can lead to low amounts of testosterone and reduced sex drive. Also, an abnormally low amount of thyroid hormone may decrease sex drive by causing a slowdown in the metabolism of the reproductive organs. Tumors of the pituitary gland (which controls most hormone production, including sex hormone) are a rarer cause of loss of libido. Because libido is sensitive to hormone levels as well as to general nutrition, health, drugs, and overall fitness, the assessment and the treatment must take into account all of these possibilities.