Not long after going through menopause, Denise Roberts (not her real name) began to feel severe pain during sexual intercourse with her husband. Penetration, she says, "felt like a knife inside me." The estrogen and vaginal lubricants recommended by the various physicians she saw offered little relief. She felt ashamed, anxious, and inadequate as a wife, and she dreaded having sex.

Denise's pain and frustration persisted for eight years before she heard about pelvic floor physical therapy, a technique that helps relax and strengthen muscles in the vaginal area. After several months of therapy and continued use of estrogen and lubricants, Denise felt much better. "It's like a miracle," she says.

Millions of women experience pain before, during, or after sexual intercourse—a condition called dyspareunia (from the Greek dyspareunos, meaning "badly mated"). This condition not only saps sexual desire and enjoyment, it can also strain relationships and erode quality of life in general. For postmenopausal women, dyspareunia may also raise concerns about aging and body image.

Many women suffer in silence and don't seek the help they need, or they have trouble finding a clinician who can diagnose and treat the causes of their pain. That is unfortunate, because treatments are available for many of the problems that underlie this vexing condition.

What is it?

Dyspareunia (pronounced dis-pah-ROO-nee-uh) can happen at any age, but it's particularly common among women who've reached menopause. Studies and surveys suggest that one-quarter to one-half of postmenopausal women experience some pain during sex. The pain can range from mild to excruciating; sufferers describe it as burning, stinging, sharpness, or extreme tenderness. Depending on its cause, pain may be located in the outer genitals (vulva), within the vagina, or deep in the pelvis. Many women feel discomfort mainly in the vestibule, the nerve-rich area surrounding the vaginal opening. Dyspareunia can start suddenly or develop gradually. Pain may occur every time with sex, or only occasionally. For some women, simply thinking about intercourse can start a cycle of tightness, pain, and avoidance of sex.

What causes it?

Possible causes include hormonal changes, various medical or nerve conditions, and emotional problems such as anxiety or depression. Often, many are at work. "One thing can easily trigger a cascade of problems," says Dr. Elizabeth G. Stewart, a vulvovaginal specialist at Harvard Vanguard Medical Associates in Burlington, Mass. and Harvard-affiliated Beth Israel Deaconess Medical Center in Boston.

Vaginal atrophy, the deterioration of vaginal tissue caused by estrogen loss, is a major source of painful intercourse for women at midlife. When ovarian production of estrogen declines at menopause, vaginal tissue may become thinner, less lubricated, and less elastic. Eventually these changes can result in vaginal dryness, burning, itching, and pain. (Reduced sexual activity as well as medications such as antihistamines can contribute to vaginal dryness.)

Another culprit is vestibulodynia (also known as localized provoked vulvodynia), a chronic pain syndrome affecting the vestibule. Any kind of touch or pressure—not only from penetration but even from a tampon, cotton swab, tight jeans, or toilet tissue—can trig ger discomfort. Vestibulodynia is a type of vulvodynia, or unexplained and persistent pain in the vulvar area. The condition appears to have several different causes.

Vestibulodynia is the most common cause of sexual pain in women under age 50, and it may be more common among postmenopausal women than previously recognized, according to a recent study by investigators at McGill University in Montreal. Researchers analyzed data from 182 postmenopausal women with dyspareunia and found that almost all (98%) felt pain when touched on the vestibule with a cotton swab during an exam; 64% had both vestibulodynia and vaginal atrophy, 14% had vestibulodynia alone, and 9% had atrophy alone. Findings appeared in the Journal of Sex & Marital Therapy (March/April 2012).

Other causes of pain with intercourse include skin diseases in the genital area, such as eczema and psoriasis; conditions such as endometriosis, pelvic inflammatory disease, bladder prolapse, and infections of the urinary tract, vagina, or reproductive organs; certain cancer treatments; injury to the pelvic area from childbirth; reconstructive surgery; damage to the pudendal nerve, which supplies the vaginal area; musculoskeletal complaints, such as arthritis or tight hip or pelvic muscles; and some kinds of male sexual dysfunction (prolonged intercourse may increase vaginal friction and pain).

Psychological or emotional factors may be involved. Stress, anxiety, depression, guilt, a history of sexual abuse, an upsetting pelvic exam in the past, or relationship troubles can also be at the root of sexual pain. Some women experience vaginismus—involuntary clenching of vaginal muscles to prevent penetration. Vaginismus is especially common among women who associate the vaginal area with fear or physical trauma. "If you've had a painful early experience, like a horrible episiotomy repair, the pelvic floor muscles seem to remember and make the vagina say, ‘Nothing comes in here,' " says Dr. Stewart.