Why ‘Female Viagra’ Isn’t Really Like Viagra

The drug flibanserin, which is being sold by Sprout Pharmaceuticals under the brand name Addyi , is the first drug approved to treat a lack of female sexual desire. Some are calling it ‘female Viagra’—but while both pills are meant to improve sex lives, the similarities end there.

Viagra is an erectile dysfunction treatment and increases blood flow to man’s genital area to help him achieve and maintain an erection. But flibanserin doesn’t treat a physical ailment, and the U.S. Food and Drug Administration (FDA) says it hasn’t been shown to enhance sexual performance. Instead, it aims to improve lagging libido in premenopausal women who are distressed by their low desire for sex, a condition called hypoactive sexual desire disorder (HSDD).

MORE: ‘Female Viagra’ Drug Approved By FDA

Scientists understand how flibanserin works, but not necessarily why the mechanics of the drug lead to improved sexual desire and less stress. The drug targets neurotransmitters thought to be involved in sexual desire; it increases dopamine and norepinephrine levels while decreasing serotonin levels. In an email to TIME, a spokesperson for Sprout Pharmaceuticals said dopamine and norepinephrine are responsible for sexual excitement, and serotonin is responsible for sexual satiety and inhibition.

Also unlike Viagra, flibanserin is a medication taken every day (close to bedtime.) Viagra is only taken as needed. Data from the makers of Viagra suggest that the drug helped approximately four out of five men get and maintain erections. About 85% of men taking 100 mg of Viagra had hard erections compared to 50% on placebo. Data from flibanserin—which included three 24-week randomized, double-blind, placebo-controlled trials in about 2,400 premenopausal women with HSDD—is less impressive. The women who took a 100 mg nighttime dose of the drug showed that on average, being treated with flibanserin increased the number of sexually satisfying events by 0.5 to one additional event per month over placebo and increased desire by 0.3 to 0.4 points over placebo.

MORE: See How ‘Female Viagra’ Works

One of the reasons critics opposed the approval of flibanserin is that they believe the benefits of the drug are not great enough to override possible side effects. When the FDA approved the drug Tuesday, it cited serious risks that could come from taking flibanserin and drinking alcohol, which include severely low blood pressure and loss of consciousness. For that reason, among others, the FDA said the drug will only be available through specially certified health care professionals and certified pharmacies and will include a boxed warning of its side effects.

“There is no black box warning [for Viagra]. They tell you not to take it on a full stomach, but that’s not a medical restriction,” says Leonore Tiefer, a clinical associate professor of psychiatry at NYU School of Medicine. “This drug, [flibanserin], has all of these limitations, and it affects the brain.”

The decision to take flibanserin lies with women and their physicians, but it may be in a consumer’s best interest to understand the distinctions between the little blue pill and the little pink one.