A woman's sexual desires naturally fluctuate over the years. Highs and lows commonly coincide with the beginning or end of a relationship or with major life changes, such as pregnancy, menopause or illness. However, if you are bothered by a low sex drive or decreased sex drive, there are lifestyle changes and sex techniques that may put you in the mood more often. Some medications offer promise as well.

Even researchers disagree about the best measure of low sex drive in women. After all, perfectly normal women vary greatly in their desire for sex and their views about the optimal amount of sex. Besides, the number of times you have sex each week isn't necessarily a good measure of your libido; women skip sex for many reasons that have nothing to do with desire, including fatigue, stress, poor body image or lack of emotional intimacy.

So, what exactly is low sex drive in women? In medical terms, you have hypoactive sexual desire disorder if you have a persistent or recurrent lack of interest in sex that causes you personal distress. But you don't have to meet this medical definition to seek help. If you aren't as interested in sex as you'd like to be, talk to your doctor.

Obviously, the major symptom of low sex drive in women is a low or absent desire for sex. According to some studies, more than 40 percent of women complain of low sexual desire at some point. The percentage is smaller — 5 percent to 15 percent — if you only count women with ongoing problems.

Still, researchers acknowledge that it's difficult to measure what's normal and what's not. If you want to have sex less often than your partner does, neither one of you is necessarily outside the norm for people at your stage in life — although your differences may cause distress. Similarly, even if your sex drive is weaker than it once was, your relationship may be stronger than ever. Bottom line: There is no magic number to define low sex drive. It varies from woman to woman.

A woman's desire for sex is based on a complex interaction of many components affecting intimacy, including physical well-being, emotional well-being, experiences, beliefs, lifestyle and current relationship. If you're experiencing problems in any of these areas, it can affect your sexual desire. In other words, there are dozens of reasons you may not be interested in sex:

Physical causes
A wide range of illnesses, physical changes and medications can cause a low sex drive, including:

• Sexual problems. If you experience pain during sex (dyspareunia) or inability to orgasm (anorgasmia), it can hamper your desire for sex.
• Medical diseases. Numerous nonsexual diseases can also affect desire for sex, including arthritis, cancer, diabetes, high blood pressure, coronary artery disease and neurological diseases. Infertility also can contribute to low sex drive, even after infertility treatments are over.
• Medications. Many prescription medications — including antidepressants, blood pressure medications and chemotherapy drugs — are notorious libido killers. Antihistamines also can zap your sex drive.
• Alcohol and drugs. A glass of wine may make you feel amorous, but too much alcohol can spoil your sex drive; the same is true of street drugs.
• Surgery. Any surgery related to your breasts or your genital tract can affect your body image, function and desire for sex.
• Fatigue. The exhaustion of caring for aging parents or young children can contribute to low sex drive.

Hormone changes
Changes in your hormone levels may change your desire for sex:

• Menopause. Estrogen helps maintain the health of your vaginal tissues and your interest in sex. But estrogen levels drop during the transition to menopause, which can cause a double whammy — decreased interest in sex and dryer vaginal tissues, resulting in painful or uncomfortable sex. At the same time, women may also experience a decrease in the hormone testosterone, which boosts sex drive in men and women alike. Although many women continue to have satisfying sex during menopause and beyond, some women experience a lagging libido during this hormonal change.
• Pregnancy and breast-feeding. Hormone changes during pregnancy, just after having a baby and during breast-feeding can put a damper on sex drive. Of course, hormones aren't the only factor affecting intimacy during these times. Fatigue, changes in body image and the pressures of carrying — or caring for — a new baby can all contribute to changes in your sexual desire.

Psychological causes
Your problems don't have to be physical or biological to be real. There are many psychological causes of low sex drive, including:

• Mental health problems, such as anxiety or depression
• Stress, such as financial stress or work stress
• Poor body image
• Low self-esteem
• History of physical or sexual abuse

Relationship issues
For many women, emotional closeness is an essential prelude to sexual intimacy. So problems in your relationship can be a major factor in low sex drive. Decreased interest in sex is often a result of ongoing issues, such as:

• Lack of connection with your partner
• Unresolved conflicts or fights
• Poor communication of sexual needs and preferences
• Infidelity or breach of trust

Talk to your doctor if you are bothered by your level of desire for sex — whether you're actually having sex just once in a while or several times a week.

Primary care doctors and gynecologists often ask about sex and intimacy as part of a routine medical visit. Take this opportunity to be candid about your sexual concerns. If your doctor doesn't broach the subject, bring it up. You may feel embarrassed to talk about sex with your doctor, but this topic is perfectly appropriate. In fact, your sexual satisfaction is a vital part of your overall health and well-being.

Once you bring up your concerns about low sex drive, your doctor will probably look for a physical cause of the problem, such as a prescription or over-the-counter medication you're taking. Undiagnosed medical conditions such as diabetes or high blood pressure can also reduce your libido. During a pelvic exam, your doctor can check for signs of physical changes contributing to low sexual desire, such as thinning of your genital tissues, vaginal dryness or pain-triggering spots. He or she may also recommend additional screening tests, thyroid studies and questionnaires to help pinpoint your level of desire and find a reason for low desire. In addition, you may be referred to a specialized counselor or sex therapist to evaluate emotional and relationship factors that can cause low sex drive.

By definition, you may be diagnosed with hypoactive sexual desire disorder if screening tests reveal a persistent or recurrent lack of sexual thoughts or receptivity to sexual activity, which causes you personal distress. Whether you fit this medical diagnosis or not, your doctor can look for reasons that your sex drive isn't as high as you'd like and find ways to help.

There is no simple pill or potion to increase sex drive in women. In fact, most women benefit from a multifaceted treatment approach aimed at the many causes behind this condition. This may include sex education, counseling, lifestyle changes and sometimes medication.

Lifestyle changes you can make
Healthy lifestyle changes can make a big difference in your desire for sex:

• Exercise. Regular aerobic exercise and strength training can increase your stamina, improve your body image, elevate your mood and enhance your libido.
• Stress less. Finding a better way to cope with work stress, financial stress and daily hassles can enhance your sex drive.
• Be happier. A sense of personal well-being and happiness are important to sexual interest. So find ways to bring a little extra joy to your world.
• Strengthen your pelvic muscles. Pelvic floor exercises (Kegel exercises) can improve your awareness of the muscles involved in pleasurable sexual sensations and increase your libido. To perform these exercises, tighten your pelvic muscles as if you're stopping a stream of urine. Hold for a count of five, relax and repeat. Do these exercises several times a day.

Relationship changes you and your partner can make
For women, better emotional intimacy often leads to better sexual intimacy:

• Communicate with your partner. Conflicts and disagreements are a natural part of any relationship. Couples who learn to fight fair and communicate in an open, honest way usually maintain a stronger emotional connection, which can lead to better sex. Communicating about sex also is important. Talking about your likes and dislikes can set the stage for greater sexual intimacy.
• Seek counseling. Talking with a sex therapist or counselor skilled in addressing sexual concerns can help with low sex drive. Therapy often includes education about sexual response and techniques and recommendations for reading materials or couples' exercises.
• Set aside time for intimacy. Scheduling sex into your calendar may seem contrived and boring. But making intimacy a priority can help put your sex drive back on track.
• Add a little spice to your sex life. Try a different sexual position, a different time of day or a different location for sex. If you and your partner are open to experimentation, sex toys and fantasy can help rekindle your sexual sizzle.

Medical treatments for low sex drive
Medications aren't always necessary to treat low sex drive. But they can help.

• Treating underlying causes of low sex drive. The first medical intervention for low sex drive is usually addressing an underlying medical condition or medication that's known to have sexual side effects. This may include adjusting or changing your current medications or starting treatment for previously undetected conditions.
• Estrogen therapy. Systemic estrogen therapy — by pill, patch or gel — can have a positive effect on brain function and mood factors that affect sexual response. Local estrogen therapy — in the form of a vaginal cream or a slow-releasing suppository or ring that you place in your vagina — can increase blood flow to the vagina and help improve desire. In some cases, your doctor may prescribe a combination of estrogen and progesterone.
• Testosterone therapy. Male hormones, such as testosterone, play an important role in female sexual function, even though testosterone occurs in much lower amounts in women. However, replacing testosterone in women is controversial and it's not approved by the Food and Drug Administration (FDA) for sexual dysfunction in women. Plus, it can cause negative side effects, including acne, excess body hair (hirsutism), and mood or personality changes. Testosterone seems most effective for women with low testosterone levels as a result of surgery to remove the ovaries (oophorectomy). If you choose to use this therapy, your doctor will closely monitor your symptoms and blood levels to make sure you're not experiencing negative side effects.

Low sex drive can be very difficult for you and your partner. It's natural to feel frustrated or sad if you aren't able to be as sexy and romantic as you want — or you used to be. At the same time, low sex drive can make your partner feel rejected, which can lead to conflicts and strife. And this type of relationship turmoil can actually add to your lack of desire for sex.

It may help to remember that fluctuations in your sex drive are a normal part of every relationship and every stage of life. Try not to focus all of your attention on sex. Instead, spend some time nurturing yourself and your relationship. Go for a long walk. Get a little extra sleep. Kiss your partner goodbye before you head out the door. Make a date night at your favorite restaurant. Feeling good about yourself and your partner can actually be the best foreplay.