Can we be real for a minute? We've all gone longer than we'd care to admit without washing our hair. Washing, drying, and styling our manes is a whole thing and, sometimes, you just can't be bothered to do it. But, what if you skipped washing your hair for longer than a few days? What if you went weeks, months, or even years — yes, years — without shampooing your locks?


In the early 1900s, this would've been the case for all women. Nicole Rogers, assistant clinical professor of dermatology at Tulane University in Louisiana, explained to Health that modern shampoo is relatively new. Prior to the '30s, people would use bar soap to clean their hair. Once shampoo arrived on the scene, it wasn't used with the frequency it is today. "Women would go to the salon and get their hair set, using products that were meant to hold their style for several days, because the act of drying and styling took so long," said New York City-based celebrity hair stylist Sarah Potempa.

While many people in the United States now wash their hair on a near-daily basis, there are others who've joined the "No Poo" movement and given up shampoo entirely. Is that a good idea? Well, here's what could happen when you give up on washing your hair.


Dry hair will be a thing of the past

If you're someone who washes your hair on the reg, you may have noticed some seriously parched strands. One of the benefits of forgoing daily shampoo sessions is the return of nourished hair. While you may think conditioner is the best thing you can use to prevent dry hair, our scalps are actually pretty proficient at doing that all on their own.

"Sebum is produced by each individual [hair] follicle via the sebaceous gland," Guy Parson, a hairstylist and certified trichologist, told Harper's Bazaar. Sebum, or oil, is, of course, responsible for making our hair feel greasy in between washes, but it's also what our scalps produce to naturally hydrate our hair. "This sebum is just as important to get silky strands as any conditioner you can purchase,"  Elle Kinney, a hairstylist at Livian Salon in New York City, told Prevention. If left to its own devices, your hair's oil will effectively hydrate your strands.


Hello, shiny hair

When shampooing your hair, you may be cleansing it, but you're also stripping your scalp of what it needs to make your hair shiny. "Hair will certainly be more lustrous when given time to renew in its own oils," Kinney told Prevention. And, really, who doesn't love shiny hair? Unfortunately, your scalp is not exactly great at evenly distributing oil. This is why the tips of your hair can look dry while your roots will look mighty greasy when you skip a wash.

If you want to maximize shine, Kinney suggested using a flat boar bristle brush to pull the oil from your roots all the way down to the ends of your hair. Lorean Cairns, co-founder of Fox & Jane hair salon in New York City agrees. She explained to Bustle, saying, "Using a boar bristle brush is great, because the natural fibers help distribute the natural oils throughout your hair."

Say bye-bye to a greasy scalp and hello to a shiny head of hair.


You might just experience a breakthrough

If you decide to give the "No Poo" movement a go, you may just experience a total hair breakthrough. Once you're several weeks in, your hair may start readjusting to infrequent washings and, instead of being a greasy mess, will start to look incredibly healthy.

"Certainly there is some truth to that," Angela Lamb, a board-certified dermatologist with Mount Sinai Hospital in New York, confirmed to USA Today. However, a lot of the results you will, or will not, experience comes down to what type of hair you're working with. Lamb explained that women with fine hair or those with naturally less oily locks usually have more success when going shampoo-free. Curlier hair, too, can often survive — and thrive — without frequent shampooing.

If you're not sure if your hair could handle weeks without washing, Lamb suggests trying three to four days to start. If your hair feels greasy, you've got the all clear to proceed. If you develop redness or itchy scales on your scalp, though, it's time to suds up. "That's your body trying to tell you that it needs more frequent washing," she added.


You could get some serious product buildup

Just because you've chosen not to use shampoo doesn't mean you have to give up all of your styling products, right? Well, you may want to consider, at the very least, cutting back. Annie Chiu, a dermatologist in Redondo Beach, California, told Prevention what happens when you add product without later taking it away. Styling creams and other products tend to stay on your scalp if you don't use shampoo to get rid of them. When that happens, the residue can become visible and your hair could even start looking a bit lackluster. This all happens pretty quickly, too. In just a few days of not washing your hair, you may experience some scalp inflammation. "This feels and looks like pimples on the scalp, and can be tender and uncomfortable," Chiu said.

So, what should you do? If your scalp experiences these issues, there may not be much else you can do but give in and use shampoo. Lorean Cairns, as referenced above, told Prevention, "Clarifying shampoos are the best way to get rid of buildup of any kind." In order to avoid drying out your hair, clarifying once a month should be enough.


What's that smell?

This is arguably the grossest part of the shampooless trend, but it would be remiss to exclude it: Your hair may start to smell pretty funky when you stop washing it.

Dr. Lamb told USA Today that while not everyone who skips washing their hair will develop a foul odor, those who do may have to endure smelling like sour milk — seriously. According to Lamb, hair traps moisture, which in turn collects bacteria. In just about a week, you may get a tinge of a mildew scent or, worse, a sour smell emanating from the top of your head.

A lot of the science behind the stench has to do with your lifestyle. "If you run five miles a day, you can't go three months without washing your hair," Lamb put it bluntly. And if you have thick hair? Watch out: you're at risk for some real deal malodorous hair.