Millions of American women who've tried everything from vibrators to romantic getaways to testosterone injections to restore their waning sexual desire will soon be able to ask their doctors for a new drug to boost their libidos. The U.S. Food and Drug Administration announced on Tuesday its approval of Addyi, also known as flibanserin, to treat hypoactive sexual desire disorder (HSDD) in women.

Now, Sprout Pharmaceuticals, the drug’s maker, is poised to capitalize on a treatment that it says could help 16 million American women who suffer from HSDD to regain their sex drive. HSDD is defined as a sudden and persistent loss of sexual desire. Women who have it do not engage in sexual fantasies or initiate sex with their partner, and say this loss of libido is a source of anxiety.

The agency’s endorsement comes at the end of a long and fiery debate. On one side stood feminists and physicians who publicly decried the lack of treatments for women’s sexual disorders. On the opposing side were medical experts who questioned the pill's effectiveness and expressed concerns about its numerous side effects. The FDA rejected applications for the drug in 2010 and 2013 due to safety concerns and a low success rate.

Raleigh-based Sprout has been at the heart of the controversy as opponents criticized the company for using aggressive tactics to pressure the FDA to approve Addyi. The company sponsored an advocacy group called Even the Score that accused the agency of sexism for failing to approve any treatments for sexual dysfunction in women. Cindy and Bob Whitehead, who founded Sprout Pharmaceuticals, also have a history of pushing the limits of advertising. While working at their former company, Slate Pharmaceuticals, the FDA reprimanded them in 2010 for making false and misleading statements related to a testosterone treatment for men. 

Addyi regulates two neurotransmitters -- dopamine and serotonin -- in the brain's frontal cortex, which are thought to control hormones related to sexual desire. However, physicians aren't sure what role these neurotransmitters actually play in causing HSDD. They also can't explain exactly how Addyi boosts libido in women who are helped by the drug. 

The FDA’s concerns over Addyi’s side effects may still restrict the number of doctors and pharmacists who are willing to offer it to patients. Common side effects of Addyi include dizziness and sleepiness. A few patients who took a too-high dose or consumed alcohol with the medicine in clinical trials also experienced a drop in blood pressure that caused them to faint.

To counter these risks, the FDA has directed Sprout to roll out a safety program alongside Addyi’s debut that educates physicians and pharmacists on how to properly prescribe the drug and closely tracks side effects in patients. Critics and FDA officials will be watching closely to see whether their concerns were merited.  

Sprout estimates that Addyi will be available to patients as soon as Oct. 17.