Hygiene Myth 3: Brushing Your Teeth in the Shower Is Basically the Same as Using the Sink
Clarkson revealed she has another double-tasking hygiene habit. “I don’t regularly brush my teeth in the shower,” she said. “I just do it if I’m in a hurry.” She added: “I do happen to be in a hurry a lot.”

Keeping a toothbrush in the shower for emergency situations may seem like a time-saving option. But it’s not a good idea, says Garshick. “The shower is a moist environment where bacterial overgrowth can occur,” she explains.

If you are going to brush your teeth in the shower, timing is key. “it is important to do so before cleansing your body,” says Garshick. “That way the soap or cleanser will help rinse away any toothpaste residue.”

Hygiene Myth 4: You Don’t Need to Bathe if You Don’t See Dirt
Actors Ashton Kutcher and Mila Kunis stirred up a little controversy when they revealed that bathing isn’t a part of their family’s daily schedule. During a July 2021 appearance on Dax Shepard and Monica Padman’s podcast Armchair Expert, the celebrity couple divulged that they bathe only when absolutely necessary.

"Here's the thing — if you can see the dirt on ’em, clean ’em. Otherwise, there's no point,” Kutcher said about when they opt to give their kids a bath. As for Kunis herself, she says she doesn’t wash her whole body with soap every day, “but I wash pits and tits and holes and soles,” while her husband joked that he washes his “armpits and my crotch daily, and nothing else ever.”

Shepard, also an actor, agreed with the couple. "You should not be getting rid of all the natural oil on your skin with a bar of soap every day," he said on the podcast. "It's insane." In an August 2021 episode of The View, he and his wife, the actor Kristen Bell, said that bath time isn’t a priority for their kiddos, either, saying it’s sometimes an afterthought. “Yeah, we forget,” Bell said on the show.

The celebrity couples aren’t wrong when it comes to this hygiene habit, says Darren P. Mareiniss, MD, the chairman of the department of emergency at RWJBH Trinitas Regional Medical Center in Elizabeth, New Jersey. “Daily showers can dry your skin, and antibacterial soap can kill normal skin flora,” he explains.

That said, daily showers are not a real cause for concern or a health hazard, notes Dr. Mareiniss.

In some cases, skipping showers may be a bad idea. Richard Antaya, MD, the director of pediatric dermatology at Yale in New Haven, Connecticut, says a daily shower can be beneficial for those with certain skin disorders, such as atopic dermatitis, the most common form of eczema. A review published in Dermatology Research and Practice found a daily shower wasn't harmful for people with eczema, though the ideal bathing frequency for this group isn't known.

In people without eczema, Mareiniss points out that failing to shower adequately can result in body odor and fungal and bacterial infections. “However, it is not necessary to shower every day unless you are particularly dirty or grimy.” Showering several times a week is usually adequate to ensure proper hygiene.

Hygiene Myth 5: You Need to Use Q-tips to Clean Your Ears
Q-tips were invented in 1923, when the company's founder, Leo Gerstenzang, observed his wife adding wads of cotton to toothpicks in order to clean out their baby’s ear. But the company no longer formally endorses them for hygienic purposes.

Douglas M. Hildrew, MD, an otologist and the medical director of the hearing and balance program at Yale , confirms that the idea that you need to stick them in your ears to clean them is false — and potentially unsafe.

“The ear canal is designed to be a self-cleaning structure. While the ear is constantly making wax and shedding dead skin cells, it is also designed with a natural migration pattern that pushes any excess buildup out of the ear canal,” he explains.

Additionally, ear wax has antimicrobial properties that destroy bacteria before they can create an infection and works as a moisturizer for the ear canal, Dr. Hildrew says.

Not only are Q-tips unnecessary to clean your ears — they can cause damage. “The combination of thin skin lying right on top of hard bone makes the skin quite vulnerable to tearing if poked at with a Q-tip, paperclip, or hairpin. Small tears in the skin can lead to bleeding and painful infections,” Hildrew explains.

Hygiene Myth 6: Douching Will Clean Your Vagina
Like your ears, your vagina cleans itself. Impressive, right?

That doesn’t mean people haven’t tried to help it out — with douching, for example. Douching dates to the 19th century. It has been used for everything from birth control, with Lysol touted as the active, sperm-killing ingredient in the 1930s, according to Smithsonian Magazine, to infection prevention. But there is zero proof behind these claims.

“In fact, douching is often damaging to the vaginal flora (normal bacteria present) and changes the natural pH in the vagina,” says Mareiniss, noting that the majority of doctors do not recommend the practice. “By douching, women can increase the risk of bacterial vaginosis (BV) — a vaginal infection — pelvic inflammatory disease, and ectopic pregnancy.” What's more, the Office on Women’s Health advises that this unneeded cleaning can make you more likely to develop sexually transmitted infections (STIs). Douching during pregnancy can even cause preterm labor, Mareiniss says.

Hygiene Myth 7: Always Wash Your Hands With Hot Water
It’s true: Boiling water effectively kills harmful bacteria, as the World Health Organization points out. But there’s no scientific evidence that washing your hands with scalding hot water is necessary to clean them, Mareiniss says. He maintains that warm water is just as effective as hot.

Far above temperature, the most important factor is soaping your hands even before you get them wet. “Rub the [liquid] soap into your hands, and then rinse with water to get all the soap and dirt off,” he notes. And of course, wash for at least 20 seconds.

Hygiene Myth 8: The 5-Second Rule Means Food Is Safe to Eat
The five-second rule originated in the 1200s, when Genghis Khan reportedly implemented the “Khan rule” at his banquets, stating that “if food fell on the floor, it could stay there as long as Khan allowed,” according to the Science Friday website.

Over the years, it turned into the “five-second rule,” which you probably heard about as a kid. But dropping food on the floor for even one second and then eating it may be harmful, says Thomas Murray, MD, PhD, a pediatric infectious diseases specialist and an associate professor of pediatrics at Yale . “Bacteria can attach to food as soon as it hits the ground,” he explains. “The longer it sits there, it is reasonable more bacteria may attach, but I don’t think one can assume if food is picked up in five seconds it is not contaminated.” This is especially true if this surface, such as a floor, is not cleaned frequently.