(CNN) -- When Cyndi met her husband at a picnic on the beach nearly 20 years ago, the two had instant physical chemistry. "We would kiss and my hormones would go riding. I'd want it to last forever, more and more and more."

But shortly before her marriage, she noticed something had changed. "It took a few weeks for me to realize. But, I said, 'Hey wait a minute. For the last few weeks, I haven't responded when we kissed.' "

A 2008 survey of more than 30,000 U.S. women published in the journal Obstetrics & Gynecology found that nearly 40 percent reported that they'd had a sexual problem at some point in their lives, with low desire being the most common issue. Although it usually is a private matter, more women are sharing their frustrations online on sites like the Circle of Moms. The progress toward a drug that could boost women's libido has also sparked more conversation, including responses to a recent CNNHealth blog. Now that possible solution may be one vote away.

On Friday, an advisory committee to the Food and Drug Administration declined to recommend approval of a highly anticipated new drug, flibanserin, saying it was not adequately effective at improving a woman's sex drive. Although advisory panels' advice is not a final decision, the FDA usually follows their recommendations.

Flibanserin, a type of antidepressant medication, works by balancing the brain chemicals linked to sexual desire. Hopes for its approval had been tempered Wednesday after an FDA review of studies found that when compared with a placebo, the response rate of flibanserin was "not compelling," and the drug yielded only slight improvements for treating the condition.

Cyndi, 24 at the time, was in the process of planning her wedding and had just switched jobs. She attributed her low sex drive to stress. But when, months into her marriage, she still did not want to have sex with her husband, she knew the problem was greater.

"The hormones weren't doing anything," she said. "All I wanted to do was cry because I mourned what I had."

Over the past 20 years, Cyndi said, she has explored various treatment options, including counselors, who told her to "just relax, have some wine, watch some porn," and gynecologists who suggested she switch birth control pills. She even signed up for clinical trials, submitting her body to uncomfortable and probing tests. But in the end, nothing helped.

"Something in my body just stopped working the way it was supposed to," Cyndi said through tears. "I've tried everything. I'm looking for a different level of solution here."

The quest for the "female Viagra"

Flibanserin is not the only treatment making headway. An Illinois company called BioSante Pharmaceuticals is conducting phase III clinical trials on a testosterone based product called LibiGel.

Testosterone, considered to be the principal male sex hormone, also appears in the ovaries of women. Studies show that women with low levels, especially women going through menopause, are more likely to experience lagging libido. According to BioSante Pharmaceuticals, preliminary studies of LibiGel show that women who applied a pea-sized amount of the gel to their forearm reported a 238 percent increase in satisfying sexual events during the four weeks of the trial. The maker is looking at the possible cardiovascular risks associated with the testosterone increase and hopes to submit a drug application to the FDA by the end of 2011.

In the meantime, there are very few options for women who experience problems with low sexual desire, also called hypoactive sexual desire disorder (HSDD). Other products, including a prescription-only clitoral therapy vacuum device designed to increase blood flow to the clitoris, have not been widely successful.

What's the delay?

It's been 12 years since Viagra came on the market to treat male erectile dysfunction, so why has it taken so long to find help for women?

The short answer: It's complicated.

"For men, the problem was with their genitals, and that was a lot easier to fix than fixing a problem in the brain," said Sheryl Kingsberg, a clinical psychologist and professor in both the departments of reproductive biology and psychiatry at the Case Western Reserve University School of Medicine. She said the cause of HSDD in women can be multifaceted. "For some women that's going to be biologic, so a pharmacologic option will be really important. For others, what they really need is to focus on the psychological factors that create their willingness to be sexual. Some women will be both," she said.

Dr. Leah Millheiser, director of the Female Sexual Medicine Program at the Stanford University School of Medicine, has been conducting studies looking at the MRI images of women with extremely low libido. She shows women erotic material while they undergo MRI exams and looks at the impact on neurotransmitters in their brains.

"What we found was really interesting. Women with low libido were different in terms of their brain activity while watching the sexual scenes." In the MRI images of the brains of women with low libido, the bilateral putamen was activated. That's an area of the brain associated with identifying negative facial expressions, unhappiness or neutrality. On the other hand, the MRI images of women with normal libido showed activity in the entorhinal cortex, an area of the brain where positive emotions are registered.

Millheiser said these findings are exciting because they help her counsel patients who feel as if they are the problem.

"For women with chronic low libido, it doesn't change when they meet a new partner and it doesn't change when they go on vacation. It absolutely can be a problem in their brain and they should not feel guilty."

Cyndi, now a 44-year-old mother of two, has had sex with her husband only about once every three months -- at his request -- for the entirety of their marriage. She said she is glad researchers are finally offering more concrete data, because for her the past 20 years have been a struggle. "I miss it. I miss passion. For me there's none of that because my body does not respond," she said. "I keep hoping that something will happen someday and we'll know how to fix it."