Do you need to throw out your underwear every 6-9 months? The answer is complicated.

Does underwear have a shelf life? Yup, says a viral TikTok video that suggests people should trash their undergarments every six to nine months.

In the video, posted by Tiktok user Kitty Chemist, a woman dances while a caption box reads, “How often should you throw out underwear? Six months? Once a year?” Her answer: “6-9 months.”

"Not all bacteria, pathogens and fibers can be removed during washing!" she explained in another text box.

Many commenters didn't buy it, writing, “Don’t do this. Wasteful. Bad for the environment,” “I still have underwear I got in eighth grade and I'm 22,” and “I cannot afford that." To the last message, Kitty Chemist replied, “Unseen mold and bacteria will grow.”

Kitty Chemist did not immediately reply to Yahoo Life’s request for comment, but she explained in her footage, “And for the longest time I did not know this at all until I had to find out for myself.” Five years ago, she got “recurring infections” for which she saw a gynecologist who inquired about the material of her underwear. According to Kitty Chemist, the cotton strip on her lace underwear carried traces of vaginal bacteria and the texture irritated her skin.

In another video, Kitty Chemist responded to comments that her claims were untrue, pointing to a 2019 article published in Essence. “Never keep panties for more than 6-9 months,” Dr. Tosha Rogers, an Atlanta-based OBGYN, wrote in the article. “There is a reason that they are $5 ladies: they are not meant to be held as family heirlooms. Buy 4 or 5 new undies every six months and simultaneously toss out 4 or 5 old ones.”

Rogers explained, “Your panties are the most intimately engaging garment that you’ll wear as a woman. Discharge happens as a natural occurrence. It’s not always malodorous or infected, and it can be normal. With that being said, your panties are the receptors of all the discharge. You remove your panties at the end of the day and toss them in the wash, which is typically done every week or so. Until laundry day, the discharge is soaked into the cotton crotch of the panties, creating a layer of bacteria (as in vaginitis), yeast and mold. Yes, mold. Unfortunately, conventional (natural or not) detergents are not designed specifically to remove these particular pathogens and mold.”

Jennifer Meyers, a certified nurse midwife and Mayo Clinic spokesperson, tells Yahoo Life that while there may be some truth to the idea that bacteria can linger on freshly laundered underwear, tossing it within a specific time frame is not a “hard-and-fast rule.”

“Any article of clothing that can be laundered thoroughly doesn’t necessarily need to be discarded,” she says. “Additionally, a woman’s own vaginal fluid is rarely harmful to her own body.”

Meyers advises washing underwear (and any other garment in direct contact with the armpit or genitals) with warm or hot soapy water after each use. It's good advice for those who participated in a 2019 survey by clothing retailer Tommy John, which found that 45 percent of people reported wearing the same pair of underwear for two days or longer and 13 percent to wearing the same pair for a week or longer. Male participants were two-and-half times more likely than women to skip laundry day.

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