7 Myths About Washing Your Hair and If They’re True

Alyssa Brown • May 15, 2023

Even before Hans Schwarzkopf invented liquid shampoo in 1927, people have been washing their hair using different combinations of products to clean their follicles and scalp. And with centuries of techniques, chemical compounds, and methods comes urban legends about washing your hair. And when you dissect these hair washing myths, they boil down to 2 common factors.

First, your hair is as unique as you are, literally. Just a single hair from anywhere on your body can be used to identify you (1). So, the washing method that works for one person might not work for another. This leads to the second reason which is the internet. The digital landscape is filled with articles that often contradict one another, and some are not based on science. If you use a search engine you may see “8 fab reasons to shampoo daily” right next to “7 reasons you should dare to stop washing your hair.” We’re making these titles up, but there is a likely chance they do exist, and both could show up for the same search result.

And the myths don’t stop there. You’ll see claims like “your shampoo stops working if you use it too much,” “towel drying is better than blow drying,” and even “your hair can clean itself.” So how can you tell fact from fiction, simple. Look for sourcing to science backed tests, fact checking, and make sure the sources are from reputable places. And that’s what we have done.

Here are 7 common myths about washing your hair, and our findings where you can read the science behind the truth.

If you always use the same shampoo it will eventually stop working

False: Unless the formulation changes, a shampoo will do the same thing it has always done.

Shampoos always work the same because of the chemistry behind them. If the formula hasn’t changed but you’ve started getting different results, then it’s likely because of lifestyle, environmental, or seasonal changes. These include the water you use (hard vs. soft), PH levels, styling products, nutrition, physical activity levels, etc. But environmental changes aren’t the only reason a shampoo may not be as effective.

Body factors like your age, your nutrient intake/deficiencies, and malabsorptive diseases can affect the structure of your hair (2), which would then give you different results with your normal shampoo. Also, high-glycemic foods like bowls of delicious ramen or plates of avocado toast (emphasis on the toast (avocados are good for your hair)) can cause inflammation in your body that can result in more sebum production (3). When you produce more sebum, you have more of your body’s natural oils on your scalp and hair, which could require a new shampoo.

Environmental elements like water hardness (4) and pH levels (5) also make a big difference in how shampoo works, and these can change even if you haven’t moved. Two examples are Denver changing the pH level of its water (6) and the charming city of Huber Heights softening its water supply by more than 50% (7). You didn’t do anything different, you’re the same age, but the area you live in modified your environment causing your shampoo to be less effective. Once you discover the cause, now you can find a new hair cleaning product that meets the new environmental needs, and your biological ones too.

Even changing seasons can change how a shampoo works for you. Summer tends to bring more humidity and more time outdoors, which can make your hair absorb more water (8). And winter can cause hair to dry out or get lots of static electricity from wearing cozy hats. Either of these seasonal effects can give you different results with the same shampoo.

Your hair can clean itself

False: Neither your hair nor your scalp can self clean.

As incredible as it would be, this myth is not credible. Your hair can’t clean itself because it doesn’t have any autophagosomes, which are the little vacuums that tidy up your living cells through a process called autophagy (8).

On the other hand, your scalp is working for you 24/7 by producing sebum, your body’s natural oils. But the scalp doesn’t have a sebum sensor to know if there’s too much, and if you don’t wash your hair, sebum will build up on your scalp where it collects dirt, product residue, and even dead skin cells.

This will irritate your scalp, result in greasy hair, and give off a not-so-nice odor (9) because it traps bacteria, yeast, and fungi that water alone won’t wash away (10). Your hair will also look dirty and dull since “sebum oxidizes to a brownish hue” (11), i.e. air turns sebum brown.

Washing your hair too much causes more grease

False: The opposite is actually true. Washing too little can result in too much grease and cause seborrheic dermatitis (12).

“Greasy hair” means hair with too much sebum. Sebum production varies with age, changes in hormones, certain medications, and lifestyle factors like weather and nutrition (13). But it doesn’t change with wash frequency. If you do wash too much then you will remove the sebum faster than your scalp can replace it and end up with a dry scalp and brittle hair.

Frequent shampooing makes your hair fall out

Half-true: Using the right shampoo and washing too frequently won’t cause your hair to fall out of its follicle, but if certain chemicals in the shampoo damage your scalp or if your hair is damaged from coloring or some other treatment, then you might see more shedding than usual.

We normally shed 100 hairs per day and assuming you aren’t allergic to your shampoo, frequent washing won’t change this. But washing too often can dry out your hair, making it more brittle than normal. This could cause hair to break, which could be confused for falling out. Plus, if you brush and wash your hair more often than recommended, excess hair brushing is associated with hair loss (14).

Major life changes like childbirth or the loss of a loved one can also cause a short bout of excessive shedding that’s unrelated to shower habits. Losing weight can do so as well. And if you started working out regularly to lose weight, then you might be showering more frequently, but the “hair loss” is a result of dropping the pounds vs showering more often (15).

One other thing to consider is over washing your hair, and under washing can irritate your scalp and cause you to scratch and rub it more often. When you do this you could be ripping some extra hairs out. That could cause the appearance of hair loss, but it isn’t based on the shampoo or cleaning, it is you over or underdoing it.

Make sure you rinse out ALL of the conditioner when you shower

False: This defeats the purpose of conditioning in the first place and will make your hair more susceptible to damage.

Conditioner works because the positive electrical charge in the conditioning molecules attaches to the negative charge of your hair. Conditioning molecules deposit around your hair’s cuticles to smooth the hair strand, reduce friction, and help prevent damage (16). If you wash out all of the conditioner so that your hair is “squeaky clean,” then you would have no remaining conditioning molecules on your hair strands.

Related to this myth is the infamous “scrape test” at the salon. This “test” isn’t scraping off extra product buildup on your hair. Instead, it’s peeling the cuticle layer off the hair similar to how you’d peel a carrot. Don’t ever let someone do this as it’s incredibly damaging to your hair.

Towel and air drying are better than blow drying

False: Blow drying with proper technique is better for your hair.

Using a dryer that’s too hot, or putting the dryer too close to your hair can damage your hair’s surface, but good technique will cause less damage than drying hair naturally (17). Good technique with a dryer is to keep the heat (or better yet use the cool breeze setting if your hair dryer has it) at least 6 inches away from your hair and continuously move the dryer so it’s not blowing on one spot.

Also, “air drying” can actually dry out and damage the hair’s cell membrane complex, which is the connective “tissue” that holds the hair strand together. Plus, going to bed with wet hair creates the conditions for bacteria and fungi to grow (18).

Cold water rinse makes your hair shinier

Half-true: Cold water doesn’t make your hair any shinier, but it does change how light bounces off of your hair.

Your hair shaft is covered by cuticles that overlap sort of like a roof covered by shingles. Warm or hot water causes the cuticles to stick up, and when the cuticles stick up, they point in various directions. Since they’re pointing in various directions, light bounces off of them in all directions and makes hair appear dull.

But cold water helps close the cuticles so that they’re all pointing in the same general direction, and when they do this, the light bounces off of them more uniformly. This is what makes the “shine” we see in hair.

Now that you know the truth and the science behind these common hair washing myths you won’t get “brainwashed” by all the fiction out there.