The next time you ditch your Friday-night happy-hour plans for a well-deserved night in — complete with a generous pour of wine, hydrating sheet mask, and a warm bubbly bath — heed caution. Well, at least on the bathtime front. Apparently bath bombs, a.k.a. your favorite fizzy tub accessory, could be doing more than just dispersing swirls of vivid, Instagram-friendly colors across your tub. They could be doing harm to your body.

According to SELF, bath bombs have the potential to throw off your vagina's pH balance, thanks to the uber-fragranced ingredients — often just labeled, mysteriously, "fragrance," which can encompass a wide array of chemicals — in the orbs. And when the bomb dissolves in the warm water, those additives could potentially make their way into your vagina, which puts it at risk, rendering the area more susceptible to bacteria, irritation, and potential infection.

For your vagina and bacteria to live in "perfect harmony," Michael Cackovic, an ob/gyn at the Ohio State University Wexner Medical Center, told SELF your pH level should be somewhere between a 4 and 4.5 to avoid infection. (Cackovic estimates there are between ten and 20 strains of bacteria currently living in your vagina, FYI.) That said, a number of things, including bath bombs and douching, can throw off the balance. When this happens, your vagina can become itchy and irritated.

But, luckily, not everyone will be negatively affected by bath bombs (your Friday night spa sesh lives on!). Down fall: The only real way to test the theory is to test-drive an orb to figure out your tolerance. If things feel amiss (irritation, itchiness, etc.), make an appointment with your gynecologist. Better to be safe than sorry.

And it should also be noted that along with with keeping bath bombs from your vagina, any fragranced cleansers and washes should also be avoided. Hilda Hutcherson, a professor of obstetrics and gynecology at Columbia University Medical Center, previously told Allure that cleansing with anything beyond plain 'ol water is strictly unnecessary. "The vagina is a self-cleaning organ; it takes care of itself," she says. "Of all the things that women have to worry about, washing or deodorizing their vulvas is not one of them."

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