So you found the hair routine of your dreams and your hair is magnificent, but then it just stops working. What is going on?

I'm Michelle of Lab Muffin Beauty Science, chemistry PhD, cosmetic chemist, and person with high-maintenance hair. Today, I'm going to help you work out why your products suddenly stopped working and what you can do about it.

You might need to change shampoo. First, changing your shampoo can make a difference.

I did a video about how complex shampoos are, and one big reason is the way they clean is complicated. One shampoo will work in different ways to remove different things from your hair.

For example, this shows how shampoo cleans an oil. The pink tadpoles are the surfactants, which are the cleaning ingredients from the shampoo.

They break off little bits of the oil into mini droplets. It's actually even more complex than this. A really runny oil isn't going to interact the same way with these surfactants as a really thick, sticky oil.

So some shampoos might be worse at cleaning off a particular type of substance from your hair than a different shampoo.

That means if you use a shampoo for a while, an ingredient might be building up. It could be a styling ingredient, it could be a conditioning ingredient, it could even be something from the shampoo itself.

So you might just need to rotate through a few different shampoos. A clarifying shampoo can also help, but a lot of the time these are designed to be used every once in a while.

That might not be enough to remove buildup, but it could still be worth a try. You could have also changed your other products.

Hair products are pretty complicated, so how they work with each other can make a difference. It's like a group work assignment, but for hair products. It might feel like one product is working differently, but it's actually a different product that partied too hard and didn't finish formatting the presentation that you all had to present.

like and subscribe for analogies that help me work through my trauma. Let me explain how this works for hair products. Conditioning ingredients show up in most hair products, not just conditioners, so they all end up working in tandem.

You might have added, say, a hair mask to your routine. It might be leaving an ingredient in your hair that your shampoo can't remove as easily, so now it feels like your shampoo isn't working as well anymore.

Or you might have changed shampoos. Maybe your old shampoo had some sort of conditioning ingredient that combined with everything else you're using gave the right level of conditioning.

But your new shampoo is less conditioning, so it kind of feels like your old conditioner isn't working anymore.

Maybe if you go back to your old shampoo, your conditioner might feel like it's working again.

You might have treated your hair. This is something I am very familiar with. I think we all know that chemical treatments like perms, dyes, straightening, and bleaching are really damaging, but it is a bit more complicated than that.

You can't just use a more concentrated conditioner. These treatments will actually change the chemical structure of your hair, so it won't interact with ingredients the same way.

The main thing we care about here is oxidative damage, and the main place this happens is called the F-layer.

You might have seen the structure of hair before. If we zoom into the surface of the outside layer called the cuticle, there is this thin layer of oily substances attached.

This is called 18-methyleicosanoic acid. It's like your hair's natural hair conditioner that is permanently bonded to your hair.

When you treat your hair with some sort of oxidizing chemical treatment, a lot of this will break off, and you're left with these groups, which are called sulfonates.

These are not oily. They're on the other end of the chemistry spectrum, where water is, and like water, they don't really stick to oil.

And this is a problem because a lot of hair conditioning ingredients are oily. They'll stick to the oily F-layer on less damaged hair, but they will slide right off super damaged hair.

So hair conditioners that are designed for less damaged hair are just not going to work. It doesn't matter how much you use. Plus, your hair is more damaged, so it's getting less conditioned while also needing more conditioning.

This is one big reason why I think a lot of people have a sort of crisis after they radically change their hair.

I definitely did. It felt like I just ruined my hair and there was no going back, but it turned out I just needed a different hair conditioner with more positively charged conditioning ingredients.

These new sulfonate groups on the hair are negatively charged most of the time, and opposite charges attract.

So these positive conditioning ingredients will stick more strongly to the more damaged parts of your hair, which is exactly what you want. These ingredients are also self-limiting, which means that once you have enough attached to your hair, it will get a slightly positive charge, so these positively charged ingredients will have a much harder time sticking on.

So that means your hair is less likely to get weighed down if you're using more conditioner. Here are some examples of uncharged and charged conditioning ingredients.

Now, all hair conditioners will have a mix of both categories, but conditioners for damaged hair will usually be formulated with high inputs of the charged ingredients.

So looking for products with labels like damaged, colored hair, intense repair is a good starting point. But these ingredients also show up in some other conditioners as well.

One of my favorite supermarket conditioners is the Toni & Guy Volumizing Conditioner. It has amodimethicone near the top.

I never would have tried this if I wasn't looking for charged ingredients. My hair is really coarse, so I actually have a lot of trouble with like poofy hair, and I stay away from volume products, but this works really well.

So chemical treatments are the main thing that kind of blasts away a lot of this F-layer, but there are other things that can remove it too.

The main ones we encounter every day are UV from the sun and pool chlorine. These tend to cause a lot less damage than a chemical treatment, but if you suddenly notice your hair conditioner stops working after you start swimming for six hours a day in summer, then this might be worth looking into.

Your water might have changed. A lot of people notice that their products don't work as well after they move to a different location. There are a lot of possible culprits, but one of the most common is tap water.

Some places have hard water which contains more metal ions. This is mostly calcium and magnesium, and they can interact with fatty acids and turn into tiny soap scum particles which stick to your hair and make it feel dirty.

Fatty acids aren't really common in most shampoos and conditioners anymore, but you do see them a lot in solid shampoo and conditioner bars.

You might also see them in natural soaps that are used as shampoos. These are some names that might show up in ingredient lists.

They can also be listed in the ingredients as some sort of natural fat or oil, like olive oil, beef tallow, coconut oil, along with sodium hydroxide or potassium hydroxide.

Fatty alcohols don't have this problem, and plant oils don't have this problem if there's no hydroxide base. The reactive groups stay tucked away in their structures.

You do also have some fatty acids in your sebum, which is your natural oil, and that could potentially react the same way with hard water. The hard water ions can also stick to your hair, especially if it's damaged.

It is those sulfonate groups again; they can sort of hitch a ride on them. They can then interact with products that you might use outside of the shower, like hair serums, so have a look in those as well.

On top of that, these hard water ions can make some of the ingredients in your hair products less effective for example, some of those cleaning surfactants in shampoos don't work as well in hard water.

Tap water can also have some other metal ions like copper and iron.

These are really bad because they can speed up oxidative reactions in your hair. So, they can mess up how chemical treatments like bleach and hair dye work. They can produce a lot of heat and cause way more damage than usual.

A lot of hair damage processes are also oxidative, so these ions could be speeding them up and making your hair more damaged and harder to maintain.

Copper can also turn your hair green. It's in a lot of swimming pools, so it isn't actually the chlorine's fault. So, the best thing to do here is probably try some products that don't have fatty acids and consider getting a water-softening showerhead.

Another big change that can happen with location is humidity.

Water has a huge impact on hair, and humidity especially messes around with your hair shape. When you style your hair, you're pretty much just holding it in place with hydrogen bonds.

Picture this: you and your dog go to an empty dog park. You have a nice, strong bond with your dog. You call for your dog, Dougie. Dougie comes running. Now, let's add in a whole bunch of really friendly dogs.

Your dog's distracted, you're distracted, you're both having all these extra interactions with other dogs.

Your bond with your dog is temporarily weaker. This is basically what water does to your hair. Your hair has a whole bunch of protein; the shape is held in place with hydrogen bonds. This is a bit like glue holding everything in place.

Water also forms hydrogen bonds. So, when you dump in a whole bunch of water (puppies) on your hair, your hair proteins will start forming bonds with those instead.

The proteins aren't holding onto each other as tightly, so your hair isn't held in shape anymore, and you get frizzy hair.

Styling products work by adding extra bonds to the outside of your hair strands. That adds to the hold that the hydrogen bonds are giving, but if you have high humidity, then there's more water around, a lot of those hydrogen bonds are gone.

Your styling products are kind of left doing all the work and they might not be enough anymore. Some styling ingredients can also hydrogen bond, so these water puppies will also mess up how they hold as well.

So if you're in a more humid place, you might want to try some styling products with more humidity resistance.

Hormones and aging might also be changing your natural hair. Hormones can change a lot of the stuff inside your body, and even though your hair is dead, it can still have an impact.

For example, around menopause, hair tends to become a lot thinner and there's less oil production on your scalp. That means your hair might not be getting as much of that natural conditioning.

If thinning is a problem, you might want to look for more volumizing products. If your hair feels rougher, then you might want a heavier conditioner.

There are also some medications like isotretinoin and oral contraceptives. They can also lower oil production.

During pregnancy, hair tends to grow a lot faster and becomes thicker, but after giving birth, that goes back to normal and you lose a whole bunch of hair, which is pretty disturbing.

Being really sick or really stressed can also cause a whole bunch of hair to prematurely end their growing cycle. They quickly move out of the anagen or growing phase into the telogen phase and then fall out.

This is called telogen effluvium, and the hair loss usually happens a few months after the actual stress.

And that delay means it's a lot harder to make the connection, so a lot of people end up blaming their hair products. There's also this annoying aspect of aging.

Your hair texture changes, but it doesn't like it all suddenly turns curly or straight. You just start getting more and more irregular hair strands.

It tends to start in your 30s. So now some of my hair is wavier than it used to be. It's a bit like there are multiple hair types on my head.

Now my hair feels and looks rougher than it used to, and yeah, the bleach didn't really help, but no regrets.

They could have also changed the product formula. I left this till a bit later because it's kind of obvious. Sometimes companies will just change the formula without telling anyone.

So, double-check if that ingredient list has changed. Sometimes the formula can change without the ingredient list changing as well. A lot of cosmetic ingredients aren't pure substances; they are mixtures. So, the exact properties can change.

With all the supply chain issues, a lot of companies have had to adjust their formulas. They might be getting an ingredient from a different supplier, and that will have slightly different impacts on the formula.

You could also just be taking the product for granted.

Maybe you loved the product at the start because it made a huge difference. Before, you were using a much less suitable product, but now you've been using it for a while, your expectations have risen.

You've been spoiled by the product. You aren't appreciating what it's doing anymore. This is really common.

We did not evolve to have perfect memories, and we tend to notice things that are new. We like novelty. So maybe put that product aside, try a different product for a while, or skip using it if it isn't an essential product, and then see if you can notice a difference.

I hope I gave you some insights into what's going on with your hair.

If you enjoyed this video, hit the like and subscribe. Let me know what other topics you want me to cover.

If you want more hair science, check out the playlist here.

Scientist explains: Why your hair products stopped working

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