Despite being rejected by the FDA twice, Addyi, also referred to by some as "female Viagra," has finally hit the market for $400 a month, according to the Daily Times Gazette. Although it is targeting women with hypoactive sexual desire disorder (HSDD), many have doubts about the drugs effectiveness due to its poorly understood mechanism of action and vague effects.

Sprout Pharmaceuticals and Valeant Pharmaceuticals are promoting Addyi as a drug that promotes sexual desire in women who report a loss of interest in sex, which is quite the opposite of Viagra, which has a direct physiological effect on men by acting on hormones and blood flow.

The chemical at the core of Addyi is flibanserin, which works on the central nervous system by restoring the balance of dopamine and norepinephrine, neurotransmitters linked to sexual excitement, and decreasing levels of serotonin, a neurotransmitter linked to sexual satisfaction. Despite its actions on these chemicals, the exact relationship between these actions and sexual desire are not certain.

Adding to people's fears is the fact that a small study on the drug's interactions with alcohol found a severe drop in blood pressure when the two were combined, according to The Boston Globe. Although the drug will carry a warning label regarding its effects with alcohol, whether people follow this warning is cause for concern.

Only 7 percent of premenopausal women in the United States are thought to have HSDD, a relatively small proportion compared to the one in three men over 55 that experience erectile dysfunction.