Of all the necessities involved in personal hygiene, showering would appear to be the least challenging task. You stand under a water spray, lather up, and let your body’s accumulated bacteria go down the drain. If you feel like fiddling with the temperature, hot showers are said to “open your pores.” Cold showers are alleged to make you more alert. Tolerating either extreme is a sign of attrition. Throw in a loofah scrub and you’re good.

But what if we’ve been showering all wrong? What if there is an objectively correct way to get clean that contradicts much of what we’ve learned about bathing through observation and cartoons?

THE DIRTY TRUTH ABOUT GETTING CLEAN

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If you’re lathering yourself up from head to toe, you’re doing it wrong, according to Rajani Katta, MD, clinical professor of dermatology at the McGovern Medical School at UTHealth in Houston and author of Glow: The Dermatologist's Guide to a Whole Food Younger Skin Diet. “Generally speaking, you don’t need soap all over your body unless you’ve gotten really sweaty,” she tells Mental Floss. A thorough lathering isn’t going to hurt you, exactly, but soap and hot water strip away the skin’s natural oils, drying it out and causing irritation, discomfort, or even infection. Instead, Katta says, soap “should go under your arms, around your private parts, and wherever there’s a skin fold,” which harbor greater numbers of bacteria. (Go in whatever order you like: Katta says it doesn't matter.)

As for those long, hot showers that feel particularly good after a stressful day or during the winter: While they might be psychologically beneficial, they’re not doing your epidermis much good. If water is too cold or too warm, the cells and lipids that make up our skin barrier can develop reactions. (Let too-warm water blast you in the forearm for a minute and you’ll likely see it turn red.) “Temperature extremes, whether too cold or too hot, can cause skin irritation and inflammation,” Katta says. “Ideally, you’ll want to use lukewarm temperatures and limit showers to no more than 10 or 15 minutes.” The idea is to cleanse, not antagonize, the tissue.

According to Katta, shower frequency shouldn’t weigh too heavily on your mind. If you’re breaking a daily sweat owing to work or fitness, it’s a good idea to shower daily. Otherwise, and unless your dermatologist has advised differently due to a skin condition, showering multiple times weekly is sufficient.

THE SCIENCE OF SCRUBBING

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“Body washes have kind of taken over the world,” Katta says. “It’s interesting that my younger patients all seem to use body wash while older patients tend to gravitate toward bar soaps.”

In this case, older means wiser. According to Katta, body washes have more water content that bar soaps, which means they use more preservatives and other additives to prevent or inhibit mold and bacteria growth. In some cases, those ingredients can prompt allergic reactions. If you’ve ever used a wash and then found your skin irritated, that’s probably why. “Bar soaps tend to have less [additives],” Katta says. If a wash is gentle on your skin, it’s fine to use it, but don’t discount the standard soap chunk.

(And no, bar soap does not make it more likely you’ll transmit bacteria with repeated use. Two often-cited studies in 1965 and 1988 concluded bars contaminated with staph, E. coli, and other not-so-pleasant pathogens did not pass along the germs in subsequent handling. In its guidelines for handwashing, the Centers for Disease Control and Prevention considers hand and liquid soap to be of equal efficacy.)

Don’t bother with loofahs or washcloths. While it’s not terribly likely they could harbor bacteria, they’re no more effective at dispersing soap than your fingertips, and it’s possible people with sensitive skin could find them irritating.

Once you get to your head, Katta says that shampooing is a highly individual practice that doesn’t invite objective advice. Use whatever products you like. If you have dandruff, you might want to shampoo more frequently. You can even wash your hair first thing, before the rest of your body. The only practice you want to time out is shaving: Later in the shower is better, since the warm water has had time to soften hair follicles and reduce chances of skin irritation. Immediately after showering is also a good time to clip any Howard Hughes-esque nail overgrowth.

KEEP YOUR HEAD MOIST

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The most important part of a shower has nothing to do with the shower. It’s about not letting your skin lose its moisture. Don't rub yourself completely dry: Instead, pat yourself with a towel so you remain slightly damp and then immediately apply a moisturizer to take advantage of your post-shower skin hydration.

Katta doesn’t recommend a specific brand of moisturizer, but says that thicker formulations are best. For that reason, try not to opt for anything that comes in a pump bottle. “Anything in a bottle has a high amount of water and may not lock moisture into the skin well,” she says. “Look for a cream-based formulation or ointment in a tube.” Petroleum jelly reduces moisture evaporation from skin; other ingredients like dimethicone, ceramides, hyaluronic acid, and glycerin can help lock in moisture.

If you’re wary about feeling like a greasy mess just before you leave the house, you can switch to a nightly showering routine. That way, Katta says, you can lube up without getting it on your work clothes.

Now you’re all clean. For information on how to keep your fanny sparkling, check out the best way to wipe.