Since the advent of Viagra, women have lamented that there is no pill to treat their most common sexual complaint, a low libido. Up to half of all women report that their sex drive could use a boost, but giving more hormones (as a female sexual dysfunction pill would most likely do) may not be the ticket to sexual bliss. As Australian researchers discovered, the link between hormones and a woman's sex drive isn't as clear as you might think.

What the researchers wanted to know: Do low levels of sex hormones cause a lower sex drive in women?

What they did: Voting is mandatory in Australia, so the researchers surveyed more than 1,000 women on the voting rolls in Victoria, Australia, who were between 18 and 75 years old. They excluded women taking drugs that can have sexual side effects, such as psychiatric therapy, as well as women taking birth control pills who were less than 45 years old. They took blood samples from all of the women and measured their levels of some of the hormones thought to control sex drive, such as testosterone and other androgens. They also had the women fill out questionnaires to learn more about their sexual arousal, desire, and ability to achieve orgasm.

What they found: The researchers found no association between the levels of sex hormones in a woman's blood and her sex drive. In particular, women with higher levels of testosterone were just as likely to report low libido as women with lower levels. Women who reported lower sexual well-being were more likely to have low levels of a natural steroid called DHEAS, but most women with low levels of that steroid did not report sexual problems.

What it means to you: Many things influence a woman's sex drive—stress, fatigue, and even just plain not feeling up to it. The levels of sex hormones in a woman's blood, however, do not seem to influence her sexual functioning. Some health experts have argued that testosterone could be used as a marker of sexual functioning, but this study refutes that. It does not, however, rule out the use of testosterone patches such as those that have been used somewhat successfully, though only experimentally, to help women with a low sex drive.

Caveats: Only 9 percent of the women whom the researchers asked to participate in the study agreed, an extremely low response rate that could mean the sample is biased in some way. In addition, the researchers took only one blood sample; it is possible that fluctuating sex hormone levels could be associated with how much desire a woman feels at any given time.

Find out more: A comprehensive article on female sexual dysfunction can be found on the American Academy of Family Physicians website.

The American Association for Marriage and Family Therapy has a simpler explanation.

Also check out U.S. News reporter Katherine Hobson's article on female sexual dysfunction and an experimental medication to treat it.

Read the article: Davis, S.R. et al. "Circulating Androgen Levels and Self-Reported Sexual Function in Women." Journal of the American Medical Association. July 6, 2005, Vol. 294, No. 1, pp. 91–96.

Abstract online: http://jama.ama-assn.org