It’s a tough call, and never a one-size-fits-all answer when it comes to how often one should wash their hair. Some people think their hair looks best when it is washed and conditioned every day. 

Others would be horrified at the prospect of having to wash their hair every day (this includes myself). Add to that the fact that your hair’s needs can change as you age, and it’s something that most need to figure out for themselves as they experience the ins and outs of washing often versus waiting a couple days between washings.

So, why do so many people notice their hair starts looking bad a couple days after washing? Well, there are several reasons for that. Let’s talk about them here, and discuss why it may not be such a great idea to go more than 2-3 days between washes. As hard as it is for me to admit, washing every 2-3 days has been my gold standard and I find if I go any longer my hair really starts to not look so good. Determining your best hair wash schedule is easy though, you just have to decide based on experience and personal preference. Related : Why Coconut Oil is So Good for Your Hair

1.)  Hydrogen bonds. Yep, that vaguely familiar chemistry term you may remember from your high school days has something to do with your hair's appearance.  Hydrogen bonds are the binding force that clumps the hair together. 

Separated, clean and fresh hair strands make the hair appear as if it has more body, and just make it feel lighter, more buoyant and healthier. When you wash and condition your hair, it breaks the hydrogen bonds that naturally form between the hair strands the longer it goes unwashed. Brushing your hair out can temporarily separate them again, but it tends to go back to clumping much faster when it’s not clean.

2.)  Dirt and buildup. The longer you go between washes, the more dirt, oil and pollutants build up on the hair itself and the scalp. When the scalp is not clean, the hair tends to “hug” the scalp more too, which makes the hair appear flatter. It can also make the hair appear duller since it coats the shaft and masks any natural sheen that comes through when it’s clean and conditioned. 

I’ve even noticed that my gray hairs tend to come out more then longer I’ve gone between washes, which isn’t exactly my favorite thing. The conditioning agents that help flatten the cuticle have worn off, and thin, wiry grays tend to just pop out of your hair's "general population" much more readily, making them more noticeable.  Don't forget the all-important factor of scalp health too. You really do want to keep your scalp clean and free of buildup as much as possible. This is especially true if you use styling products on the regular. It’s important to the overall health of your hair, and may even facilitate healthy hair growth and help with thinning issues.

3.)  Conditioners wear off. That fantastic invention called conditioner works wonders after a good shampoo. Conditioners make combing and de-tangling so much easier. They also enhance the shine and body of the hair when used correctly, and can even enhance the natural color and highlights you have. Since conditioners provide a temporary “coating” that really makes your hair look fabulous, they also wear off. Related: Hair color depositors between coloring - enrich and super saturate your color

Conditioner can also offer a level of protection against damaging UV rays, humidity and even lack of humidity (drying out). Your hair may start to feel more “brittle” after it wears off. If you go more than 2-3 days between washing and conditioning, you will notice that the enhancing effects conditioner provides begin to fade. So, if you want to regain that effect, it’s off the shower again for a fresh coat!

4.)  Root lift. This one is related to #2. The more buildup your scalp and hair is accumulating, the more weighed down it is. When you shampoo and condition again, you usually see an instant boost that lasts about a day or two in the lift of your roots. Root lift is a big deal if you want your hair to look super healthy and have lots of movement! Related : Should You Avoid Sulfates in Your Hair Care Products?

There are the biggest reasons I’ve found for my hair looking bad after too many days of not washing. And if that’s not enough, consider this. Every time I’ve gotten compliments on my hair – and this is without exception – it’s the day after I’ve washed and conditioned! I wash my hair at night, so the next day is always when it looks its best. 

Another tip: Try washing and drying your hair (or letting it air dry) during the day so you don't immediately sleep on it after washing/drying. This really improves your root life and body, and helps keep the hair smooth and soft. You will have to do more styling work if you immediately go to bed afterwards.

Like I said, I have the type of hair that could probably be washed every day. I just don’t want to do it. Let’s face it “wash days” are always a bit of a hassle, even if you’ve got your routine down to a science. It always feels like a luxury to skip a wash. So hey, just find whatever works best for you and your hair. After all, you and your hair are going to be together for a very long time!