(Kiichiro Sato/AP)

Anti-bacterial soaps pretty much make one promise: Namely, that they will kill bacteria.

Now the Food and Drug Administration says  that they have no evidence that anti-bacterial soaps do any better at stopping the spread of germs than less-glamorous, non-anti-bacterial soaps with no bacteria fighting powers to speak of.

"There is currently no evidence that they are any more effective at preventing illness than washing with plain soap and water," the federal agency said in a release Monday morning. What's more, the agency is worried that anti-bacterial soaps could be harmful, by increasing antibiotic resistance and posing hormonal risks.

Which is why the FDA put out a preliminary rule today that would require antibacterial soap makers to prove that their soaps do provide a clinical benefit — and one that outweighs the possible risks of regular contact with antibiotics.

“Due to consumers’ extensive exposure to the ingredients in antibacterial soaps, we believe there should be a clearly demonstrated benefit from using antibacterial soap to balance any potential risk," Janet Woodcock, who directs the FDA Center for Drug Evaluation and Research, says in a statement.

The move comes shortly after the agency announced plans to crack down on the use of antibiotics in animals raised for meat as concerns about antibiotic resistance are rising. The idea with this decision is to determine that, if Americans are going to use lots of antibacterial soap and if there are risks, it better at least do some good.

One interesting twist to the proposal that Jenny Gold noticed is that antibacterial soaps used by hospitals are exempt from these new requirements. The FDA explains this by noting that health care settings are ones where there's a higher risk of disease being spread.

"In the U.S. consumer setting, where the target population is composed of generally healthy individuals, the risk of infection and the scope of  the spread of infection is relatively low compared to the health care setting, where patients are generally more susceptible to infection and the potential for spread of infection is high," the agency writes in its preliminary regulation.

This is a bit of a weird justification, given that the agency doesn't think antibacterial soaps do any better than regular soaps at stopping the spread of bacteria. But, this is where the FDA came down on the issue, and it means soap will now face different regulations depending on where it gets used.