A woman's sexuality is a complex interplay of physical and emotional responses that affects the way she thinks and feels about herself. When a woman has a sexual problem, it can affect many aspects of her life, including her personal relationships and her own self-esteem. Many women are hesitant to talk about their sexuality with their health care professionals. Instead, they needlessly suffer in silence when their problem could be treated with medical or psychological therapy, or both.

Sex includes a wide variety of intimate activities, such as fondling, self-stimulation, oral sex, vaginal penetration and intercourse. Every woman differs in her sexual interest, response and expression. A woman's feelings about sexuality can change according to circumstances and the stages of her life. Women also can experience a variety of sexual problems, such as lack of desire, difficulty becoming aroused, or pain during sex. An occasional sexual problem that seems to go away on its own is normal. However, when the problem is persistent, or pain is involved, it's time to contact a health care professional.

Although sexual responses are highly individualized and do vary, when a woman has sex, her body goes through a pattern of responses called the sexual response cycle. The cycle consists of the following stages:

* Desire. This is the feeling that you want to have sex.

* Arousal. Physical changes occur in your body to prepare it for sex. The changes include moistening of the vagina and its opening, called the vulva; relaxation of the muscles of the vagina; swelling of the labia, (skin folds surrounding the vulva), and the clitoris (a small, sensitive organ near the opening of the vagina that acts as a source of sexual excitement); and lifting of the uterus.

* Orgasm. Known as the peak of the sexual response, the muscles of the vagina and uterus contract and create a strong feeling of pleasure.

* Resolution. The body returns to its normal state.

Sexual dysfunctions are disturbances in one or more of the sexual response cycle's phases, or pain associated with arousal or intercourse. A study published in the Journal of the American Medical Association involving a national sample of 1,749 women estimated that sexual dysfunctions occur in 43 percent of women in the United States. According to this 1999 study, you may be at greater risk for sexual problems if you are:

* single, divorced, widowed, or separated

* not a high school graduate

* experiencing emotional or stress-related problems

* experiencing a decline in your economic position

* feeling unhappy, or physically and emotionally unsatisfied

* a victim of sexual abuse or forced sexual contact

There are several types of sexual dysfunctions. They can be lifelong problems that have always been present, acquired problems that develop after a period of normal sexual function, or situational problems that develop only under certain circumstances or with certain partners. Causes of sexual dysfunctions can be psychological, physical, or both.

Psychological causes can include:

* stress or anxiety from work or family responsibilities

* concern about sexual performance

* conflicts in the relationship with your partner

* depression

* unresolved sexual orientation issues

* previous traumatic sexual experience

* body image and self-esteem problems

Physical causes can include:

* diabetes

* heart disease

* liver disease

* kidney disease

* pelvic surgery

* pelvic injury or trauma

* neurological disorders

* medication side effects

* hormonal changes, including those related to pregnancy and menopause

* thyroid disease

* alcohol or drug abuse

Lack of sexual desire is the most common sexual problem in women. The American College of Obstetricians and Gynecologists reports survey data indicating up to 30 percent of women lacked interest in sex for at least one month in the previous year. About 15 percent of postmenopausal women have decreases in sexual desire, according to The Merck Manual of Diagnosis and Therapy.

Often, sexual desire is affected by a woman's relationship with her sexual partner. The more a woman enjoys the relationship, the greater the desire for sex. The stresses of daily living can affect desire, and feeling uninterested in sex occasionally is no cause for concern. But, when sexual fantasies or thoughts and desire for sexual activity are persistently or recurrently reduced or absent, and cause distress or interpersonal difficulties, the problem is known as hypoactive sexual desire disorder, or inhibited sexual desire disorder. The Merck Manual of Diagnosis and Therapy estimates hypoactive sexual desire disorder occurs in about 20 percent of women.

Avoiding all or almost all genital sexual contact with a sexual partner, to the point that it occasionally causes personal distress and relationship difficulties is a problem known as sexual aversion disorder. This condition affects women who have experienced some type of sexual abuse, or who grew up in a rigid atmosphere in which sex was taboo. A recent study reported in the journal Archives of Sexual Behavior stated that among patients with panic disorder, 75 percent had sexual problems, and that sexual aversion disorder was the most common complaint, affecting 50 percent of women. (Panic disorder is a mental health condition that causes repeated panic attacks. These attacks trigger symptoms such as pounding chest pain, sweating, shortness of breath and dizziness, and feelings of impending doom.) Since the sexual problems may be caused by the panic disorder, drugs that keep panic attacks under control (anti-panic drugs) may have the beneficial side effect of relieving the sexual problems, according to the researchers. Overall, however, it is fairly rare that panic disorder is a cause of sexual aversion.

Sexual arousal disorder is the persistent or recurrent inability to reach or sustain the lubrication and swelling reaction in the arousal phase of the sexual response. It is the second most common sexual problem among women, affecting 15 percent to 20 percent, and most frequently occurs in postmenopausal women. Decreased estrogen levels that occur after menopause may make the vagina dry and thin, shrink vaginal tissue, and reduce blood flow to genital tissues. As a result, for menopausal and postmenopausal women, the arousal phase of the sexual response may take longer, and sensitivity of the vaginal area can decline.

Arousal disorders often lead to orgasm problems. Orgasms vary greatly in length and intensity, and often feel different at different times for women. Persistent absence or recurrent delay in orgasm after stimulation and arousal is known as female orgasmic disorder. About 10 percent of women have never had an orgasm, regardless of the stimulation or situation. About half of women regularly have an orgasm during intercourse, according to The Merck Manual of Diagnosis and Therapy.

Most women are biologically able to experience orgasm. Never having an orgasm, or not having one in certain situations, are problems that often can be corrected by learning how the female body responds, how to ensure adequate stimulation, and/or how to overcome inhibitions or anxieties.

Some blood pressure, antidepressants and antipsychotic medications can decrease desire and interfere with orgasm. If you are taking such drugs and experiencing such sexual function side effects, talk with your health care professional about changing your prescription.

Pain during or after intercourse, called dyspareunia, occurs in nearly two out of three women at some time during their lives, according to the American College of Obstetricians and Gynecologists. Like other sexual disorders, it can have physical or emotional causes, or both. The most common cause of pain during sex is inadequate vaginal lubrication that can occur from a lack of arousal, medications, or hormonal changes. Painful sex also can be a sign of illnesses, infections, cysts, or tumors needing medical treatment or surgery, which is another reason why you should discuss the problem with your health care professional.

A type of sexual pain disorder is vaginismus, which is the involuntary spasm of the muscles at the opening of the vagina, making anything entering the vagina painful. Vaginismus can have medical causes, including:

* scars in the vagina from an injury, childbirth or surgery

* irritations from douches, spermicides or latex in condoms

* pelvic infections

Vaginismus also can have psychological causes. It can be a response to a fear, such as fear of losing control or fear of pregnancy. It can also stem from pain or trauma, such as rape or sexual abuse.

According to the American College of Obstetricians and Gynecologists, a woman's sexual response tends to peak in her mid-30s to early 40s. That's not to say, however, that a woman can't have a full physical and emotional response to sex throughout her life. In fact, the 1999 JAMA study found the prevalence of many sexual problems among women tends to decrease as they age. Most people will have a passing sexual problem at some point in their lives, and that is normal.