It's hard to get excited about cotton underwear: they're not particularly sexy, seem to stain easily, and can lose their shape and become baggy pretty quickly.
But gynecologists swear by them for vaginal hygiene. "Any time women are having problems with vaginal infections, we tend to recommend cotton underwear as sort of the least triggering fabric," says Dr. Kelly Culwell, an OBGYN and former medical officer at the World Health Organization. "It's one of our many steps to vaginal and vulvar hygiene."
So, what are the benefits of wearing cotton underwear over fabrics like modal, polyester, or other synthetic blends? Here are a few of the vaginal issues a pair of 100 percent cotton undies can help prevent:
Yeast infections
The National Institutes of Health report that 75 percent of adult women have suffered from a yeast infection at some point in their lives. Symptoms include vaginal itching or soreness, abnormal discharge, pain during sex, and discomfort urinating. Yeast infections are caused by the overgrowth of the Candida fungus, which can be exacerbated by moisture-trapping synthetic underwear. For this reason, the CDC recommends wearing cotton underwear to help reduce the risk.
Urinary tract infections
Urinary tract infections, or UTIs, are also common in women. The National Kidney Foundation estimates that 1 in 5 women have experienced a UTI at some point in her life. UTIs are caused by bacterial infections that are typically in the urethra or bladder, but they can also occur in the uterus and kidneys as well. The American College of Obstetricians and Gynecologists (ACOG) recommends wearing cotton underwear to help reduce moisture and the potential growth of bacteria.
Bacterial vaginosis
According to the CDC, bacterial vaginosis is one of the most common types of vaginal infections. Although the causes are not entirely known, researchers know that BV is most common in sexually active women. To prevent BV, they suggest not having sex, reducing the number of sexual partners, and avoiding douching. Doctors also recommend that women who are experiencing BV wear cotton underwear, since the breathability of the fabric can help reduce the spread of bacteria.
Vulvodynia
Vulvodynia is a painful condition that affects the vulva, and symptoms may include stinging, burning, irritation, and rawness. Vulvodynia is caused by inflammation of the vulva, damage or irritation to the vaginal nerves, genetic disorders, sensitivity to foods, and dysfunction of the pelvic floor muscles. The ACOG also recommends that women with vulvodynia wear cotton underwear to help reduce any additional irritation to the vagina.
Which fabric should you choose?
According to Shira Wheeler, the founder of Oddo Body underwear that manufactures 100 percent cotton underwear, you should avoid any fabric that has synthetic, silk, or elastic (not including the leg- and waistbands) content. These materials can prevent air and moisture flow between your vagina and the atmosphere, and that can increase your risk of yeast infections.
"The vagina is a self-cleaning organ, but in order for it to maintain a balanced biome, it needs to breathe," Wheeler says. "If you're covering your vulva with materials that trap or absorb moisture, you're basically creating a petri dish for bacteria to live."
Are thongs bad?
From bodycon dresses to skinny jeans, the need to eliminate panty lines is ever present hence the lasting popularity of the thong (not to mention, Sisqo's 1999 hit song). But frequent thong wearers should beware.
"Some thongs and all g-strings are unhealthy because there is greater likelihood that they will move back and forth throughout the day," says Wheeler. "Again, the vagina is a sensitive biome and a G-string can transfer bacteria from the anus to the vagina as fabric shifts with wear."
To answer the question: thongs aren't necessarily bad, but they may carry more risk of infection with them.
How to care for your underwear
"I've heard from many people that their grandmothers (mine included) used to iron their underwear," Wheeler says. "We have better washing machines these days, but you should always machine wash your underwear [with] hot [water]." (Water needs to be 140-150 degrees to kill germs).
She recommends hand-washing Oddo Body's briefs, which are made from fine Japanese cotton, in warm water.
"It's important, when washing by hand, to use a delicate soap, avoid perfumes, and to pay special attention when cleaning the fabric that touches your vulva and anus," she says. "Once you've washed with soap, make sure that you've thoroughly rinsed the fabric of any soap."
So there you have it. While lacy thongs might look cute, 100% cotton granny panties are going to be there for you, healthwise. And thanks to creative people like Wheeler, we're starting to see more cotton panties on the market that are both good for your health AND easy on the eyes. Hopefully, next time you pick out your underwear, you'll think about your vagina not just your outfit.