6 Reasons You Actually Do Need to Wash Your Hair

Three days, five days, a week… The number of days one goes without washing their hair and just getting by with dry shampoo has become a point of pride these days. We even hear colleagues brag about how many workouts their most recent blowout has lasted through. (Congrats?)

But even though over-washing is indeed harsh on strands and can strip their natural moisture, experts tell us that, depending on your hair texture, there actually can be such as thing as going too long between suds. Without regular shampooing hair can become lackluster, smelly, and worse. So, today, in honor of National Shampoo Day (which falls on either the twentieth, twenty-first, or twenty-second day of October—the true date of the made-up holiday is a point of contention in the beauty industry), we asked hairstylists, colorists, dermatologists, and hair experts for the quick and dirty on coming clean.

1. Shampoo Is, You Know, Basic Hygiene How do you like the sound of “microfauna” in your hair? Us, neither. “Sebum, which is nature’s hair conditioner, is constantly secreted out of the scalp and onto the hair, and it will build-up without washing. This can leave the hair looking and feeling oily, but worse still, this sebum can act as a food source for microfauna whose action can lead to dandruff and, in extreme cases, can cause hair loss. In addition, product build-up residue from conditioning and styling ingredients will also occur without washing, which collectively can dull the hair and weigh it down. A good cleaning with a good shampoo will prevent all of these issues. In short, this new ‘no poo’ movement really is a crock of …. well, poo.”— Trefor Evans, cosmetic chemist and technical consultant to the hair-care industry

2. It Acts Like Skin Care You know what happens when you don’t wash your face—and the same goes for your scalp. “Dry shampoo will bind and pull the oil away from the scalp, but doesn't remove it and can leave hair dry. That, along with dead skin on the scalp, and hair products, like oils and volumizers, need to be removed intermittently, otherwise they can block follicles and lead to inflammation. Some newer shampoos are even designed to strengthen the hair. My favorite is Julien Farel Hydrate Restore, which includes resveratrol and antioxidants, and sits on the scalp for a few minutes before rinsing.”— Doris Day, a New York City dermatologist 

3. It’s the First Step in Style Every good blowout starts in the same place: the shampoo bowl. “Using the right shampoo for your hair type resets hair and gives you a good foundation for any style. If you have thin hair, a volumizing shampoo cleanses hair of volume-deflating build up, while a shampoo for thick coarse hair is designed to hydrate and coat the cuticle to weigh down flyaways. And if you were to skip shampoo altogether, your hair wouldn’t be prepared to hold the style you’re looking to achieve. Lastly, it’s plain-old good hygiene. No one wants to talk to someone whose B.O. enters the room before they do, and no amount of fragranced dry shampoo is truly going to mask it.”— Greg Ruggeri, stylist, colorist, and owner of Salon Ruggeri in New York City

4. Healthy Hair Starts at the Roots The health of your scalp directly translates to the health of your hair. “Since skin turns over approximately every 28 days, the build up of [dead skin] scales can grow more pronounced if you don’t wash your scalp. Washing hair has been shown to significantly reduce the level of the stress hormone, cortisol, in hair follicles and this hormone has been associated with increased hair thinning in women. Female patients often admit they're afraid to wash their scalp because they see hair in the shower drain afterwards. But we normally have about 100 hairs fall out every day and about 100 hairs grow back, so the more days we wait, the larger the number of dislodged hairs grows.

Regular cleaning with well-formulated shampoo will not damage hair. In fact, some studies show that it may help fragile hair by decreasing grooming force.”— Carlos K. Wesley, a New York City-based cosmetic surgeon specializing in men's and women's hair loss