Drugs

In addition to hormonal contraceptives, a surprising number of drugs can interfere with sexual functioning. These include:

• Antidepressants, including selective serotonin reuptake inhibitors (SSRIs), such as Prozac (fluoxetine) and Paxil (paroxetine), which can alter brain chemicals that affect sexual desire and response; they also can cause fatigue and nausea.
  
  
• Antibiotics, which can cause yeast infections, making intercourse uncomfortable.
  
  
• Antihistamines, which dry mucous membranes (including those of the vagina).
  
  
• Heart and hypertension medicines, which cause sexual dysfunction in as many as 25 percent of women taking them. In one study, women with unimpaired sexual function who were given clonidine and prazosin (antihypertensive medicines) were less likely to desire sex than those given a placebo.
  
  
• Tranquilizers, which can lower libido and delay or prevent orgasm.
  
  
• Diet aids, sleep aids, and other over-the-counter drugs, which can cause drowsiness, reduce sexual desire, and impair function.

Infection

Infections, such as urinary tract, rectal, and vaginal infections, and sexually transmitted diseases (for example, human papilloma virus, which causes genital warts) can cause pain during intercourse.

Illness or Injury

Organic diseases, such as disorders of the adrenal, pituitary, and thyroid glands (the regulators of hormones), can alter your attitude toward sex. Interestingly, oxytocin, which is secreted by the pituitary gland, has been linked in animals (not humans, yet) to the contractions of the uterus during orgasm. Oxytocin is better known as the substance given to pregnant women to induce contractions.

Chemotherapy

Side effects of chemotherapy, such as fatigue and nausea, can lower libido in cancer patients, who also may feel unattractive because of breast surgery or ostomies, for instance. Surgery for cancers of the ovary, bladder, rectum, and uterus can induce menopause, as can chemotherapy for breast cancer.

Hysterectomy

Hysterectomy can have completely opposite effects on sexual function: Half of 104 women in one study reported improvement after subtotal hysterectomy; 21 percent reported deterioration. Those who felt better were more likely to have had satisfying sex lives before the surgery.

Hysterectomy should not affect sexual desire or function if the ovaries (which produce hormones) are still intact, and hormone replacement therapy can make up for missing ovaries. Regardless, the ability to have an orgasm is unchanged, Dr. Renshaw points out, because arousal takes place in your clitoris and your mind.

Spinal Cord Injury

This type of injury does not have to close the book on sexual activity. In a 1995 study, half of 25 women with spinal cord injury reported the ability to achieve orgasm regardless of the pattern or degree of their neurological injury. What made the difference? The researchers credited greater sexual knowledge and higher sex drive.

Medical factors aren't the only causes of sexual dysfunction in women -- there also are psychological variables. See the next page to learn more.