1. Yeah, shampoos do dry out your hair
That's their job! Shampoos are designed to get rid of sebum, which is a waxy, oily byproduct of glands in your scalp. It protects the hair shaft and makes hair look shiny and healthy, but it's hydrophobic – which means that, at the molecular level, it refuses to buddy up with water. You can stand under the shower head all you want, but most of that sebum is going to stay put. The problem is that, as it accumulates, it makes hairs stick together and look greasy – and can even attract dust and pollen.
The detergents in shampoo bind to the sebum and then bind to water molecules, just like soap does with grease on your body.
2. But it's not just the shampoo that makes your hair seem dry – it's also the water
When you get your hair wet, the cuticles that usually lie flat on your hair shaft can end up getting mused. If they're sticking to and fro, your hair looks duller – and it's more fragile. Even if you're not using shampoo, rinsing your hair can leave it looking dry and vulnerable to damage.
That's where conditioner comes in – it has silicone and other compounds designed to smooth those cuticles and leave the hair looking strong and shiny.
So if you swear off shampoo and conditioner entirely, you might notice that your hair seems dull and tangly after you shower. Lots of folks offer up "natural" alternatives to fix this, but some of them do more harm than good.
3. Apple cider vinegar and baking soda is bad, and you shouldn't use it (probably)
If you've ever spent 30 seconds on Pinterest, you know that vinegar and baking soda are often touted as miraculous hair products. This "natural" way of washing hair helps "restore balance" and blah blah blah.
Natural isn't always bad, but in this case it's usually about as bad for your hair as regular shampoo, if not worse. Vinegar is very acidic, and pouring it onto your hair is going to weaken it. If your hair is weak and full of not-flat cuticles, and you scrub it with something as abrasive as a paste made from baking soda – yikes!
4. "Sulfate-free" shampoos are kind of a bust
As someone with naturally curly hair, I was on the no-sulfates train way before it was cool. The idea that more and more stylists are adopting is that sulfates, which are commonly used as detergents in shampoos, are damaging to hair – and especially to hair that tends to be dry, like curls. Some people think that curls tend to have more issues with lifted cuticles because of the way the hair twists – which would make them appear more dry. It has also been argued that sebum has a harder time making its way down a curly hair shaft, or at least that curls are less likely to appear greasy and matted when covered with the stuff.
Let's unpack this no-sulfate thing a little: Yes, all detergents, by definition, will make your hair less oily — and therefore more dry. But is one kind of shampoo better than the other? The ACS argues that the answer is no: Most sulfate-free shampoos use some kind of alternative detergent that behaves exactly the same way. If you choose a moisturizing shampoo that has less detergent, your hair might retain more oil. If you use just conditioner instead of shampoo, you'll keep even more of your oils around for the party. That's all well and good if you're trying to keep hair looking shiny, but don't buy into anti-sulfate marketing wholesale: You might just be buying expensive shampoo for no reason.
You can read a takedown of the trend over at the New York Times. The kicker is brutal and made me take a good hard look at my shower caddy.
The long and short of it? Most shampoos are basically identical. Figure out what works for your hair and run with it. Or, better yet, become a chemist and design a shampoo that actually does something new. Please?