Mary Shackelton hears stories like it almost every day.

In the privacy of her Boulder, Colo., office, women anywhere from their 20s to their 60s quietly confess that their sex drive just isn’t what it once was, and shrug their shoulders as if that’s just the way it has to be.

“When I ask about it, they kind of laugh like, ‘What libido?'”, says Shackelton, a naturopathic doctor at the Boulder Women’s Center for Natural Medicine. “They really think that there’s nothing that can be done about it.”

As recently as a decade ago, that was largely true, but thanks to an increased openness about female sexual dysfunction, a growing body of research about what causes it, and a flurry of new products aimed at treating it, that’s beginning to change, say medical experts.

Late last year, a Food and Drug Administration advisory panel voted against Procter & Gamble’s Intrinsa, a slow-release testosterone patch that, if approved, would have been the first prescription drug designed specifically to increase female sex drive.

But several over-the-counter products already are on the market, including Zestra, a cream, and Avlimil, an herbal supplement. And many more are in the pipeline, as pharmaceutical companies race to capitalize on what is estimated to be a $3 billion sales opportunity in treating what they have dubbed female sexual dysfunction (FSD) or hypoactive sexual desire disorder (HSDD).

Many women’s health care providers say they welcome the increased attention to the long-hushed topic. But they believe the burgeoning market of pills, potions and lotions should be approached with caution.

“I’m troubled by the tendency that there is to pathologize things and look for a chemical remedy,” says Susan Hubbard, a licensed clinical social worker in Boulder. “There are times when chemical remedies are marvelous, and we need them, but sometimes people are encouraged to turn to them before they can realize what is really going on with their psyches and their bodies.”

According to a study published in the Journal of the American Medical Assn., more than 43 percent of women from 18 to 59 experience sexual dysfunction, making the problem more prevalent among females than males (31 percent).

A study, published in the Journal of American Medial Assn., found more than 43 percent of women from 18 to 59 experience sexual dysfunction, making the problem more prevalent among females than males. Medical experts say an increased openness about female sexual dysfunction is leading to more research and products aimed at treating it.

Because emotional problems often follow, the report said, it should be treated as an “important health concern.”

Yet the focus has been on men. Since the 1998 release of the anti-impotence drug Viagra — which works by increasing blood flow to the penis — no company has found a successful equivalent for women.

That’s because women are far more complex than men when it comes to sex drive and sexual response, says Carol Dalton, a Boulder nurse practitioner.

As women age and estrogen levels decrease, the blood flow to the genital area also slows and nerves there start to degenerate, diminishing sexual response.

“Some women can be thinking about it, and be turned on, but physiologically, nothing happens,” Dalton says.

But then there is that other critical sexual organ — the brain.

A lack of testosterone can keep the brain from responding to romantic movies or nibbles on the ear the way it used to. But so can a host of other less-measurable problems, like stress, which can hinder adrenal gland function, or relationship problems which can overshadow a healthy hormonal system.