'Female Viagra' is here. What exactly does it treat?

After years of languishing in medical purgatory, so-called “female Viagra” was just approved by the FDA. Going by the trade name Addyi, the pill will be used to treat hypoactive sexual desire disorder, or HSDD, in pre-menopausal women.

The FDA describes HSDD as “low sexual desire that causes marked distress or interpersonal difficulty and is not due to a co-existing medical or psychiatric condition, problems within the relationship, or the effects of a medication or other drug substance.”

That’s a mouthful, so let’s break it down.

Addyi, whose generic name is flibanserin, targets a different facet of sexuality than Viagra. While the former treats issues with blood flow towards to the genitals, addressing the problem of physical arousal, Addyi treats a lack of physical desire. So the “female Viagra” label is really a misnomer.

How does Addyi work, then? Basically, it elevates the neurotransmitters dopamine and norepinephrine and decreases serotonin (which can impede sex drive). But if a lack of desire was just a matter of slight brain chemistry rejiggering—why didn’t we figure this out sooner?! Even the FDA kind of shrugs when pressed for more details. “The mechanism by which the drug improves sexual desire and related distress is not known,” the group said in its press release.

This drug is by no means a cure-all, and not everyone is impressed by its efficacy. A host of physical and emotional barriers exclude many patients from being good candidates. But for others, it holds very real promise. “I know this pill worked for me,” a woman who participated in one of the drug’s clinical trials wrote in TIME. “I want to want my husband again.”

Want to learn more about what, exactly, the pill will “treat”? Here’s a deeper dive.

Cleo Stiller is a digital producer covering the intersections of sex, tech and culture. Words to live by: get your money’s worth.