When we think about shampoo, we think about those uh... interesting '90s Herbal Essences ads. The ones that made things awkward if your parents were in front of the telly too. Or the Decore shampoo song? Great, it's stuck in our heads now.
But despite what these ads promised us, some shampoos won't change your life, or even change your hair for the better.
As scientists and hair professionals learn more about hair health, they've also discovered nasty ingredients (and hidden chemicals) in some shampoos that are likely to do more damage than good.
In this article, we'll explore which ingredients to avoid in shampoo, because your scalp deserves a day spa, not torture.
What does shampoo do for your hair and scalp?
Humans have been using shampoo in some form or another for centuries. In fact, the term comes from the Hindi word "champoo" — which means to cleanse hair and skin through massage .
Early on, shampoos were very basic soaps that left behind a lot of build-up and were hard to rinse out. Shampoos as we know them today didn't become a thing until the 1930s — and evolved from carpet cleaners and laundry detergents .
Nowadays, most shampoos on the market are a little gentler than those early versions. We use shampoos and conditioners to clean our hair, help with styling, and prevent it from damage .
Your soapy friend in the shower can come in a bunch of different formulas — lathering foam, standard liquid shampoos, and even solid shampoo bars. Other than cleansing the scalp, shampoos have been used for a whole lot of hair care concerns, such as:
- Treating dandruff
- Targeting particular hair problems, like dry or oily hair
- Caring for colour-treated hair
- Preventing or treating hair loss 
The reason shampoo became more popular is that most of the things that make our hair dirty aren't water-soluble — meaning they can't be cleaned away with water alone. This includes our hair's natural oils and sebum .
In an ideal world, a good haircare routine should leave your hair feeling cleansed, soft, moisturised, and looking lush. But what happens if your hair products have toxic chemicals hiding in them?
What ingredients should you avoid in shampoo?
Shampoo has come a long way from soapberries and herbs, but that isn't always a good thing.
Below is a list of ingredients to avoid in shampoo, some of which have been linked to hair loss, and can have harmful health effects.
The first cab off the rank is formaldehyde and formaldehyde releasers. This is an ingredient most commonly found in keratin treatments or treatments that claim to smooth the hair .
In low levels, formaldehyde is safe for companies to use as a preservative in their cosmetic products (it helps stop bacteria from growing). But when used at higher levels, formaldehyde can cause hair breakage, permanent skin irritation, dermatitis, and even asthma/breathing problems .
It's really important to check whether your hair products contain formaldehyde and if they do, whether it's at a safe concentration (around 0.05%).
To check if any products you have on the shelf at home are potentially toxic, you can visit the Australian Competition & Consumer Commission's Product Safety website.
We're not talking cocktails here, but the kind some brands use to give their shampoos and conditioners a thicker consistency .
Ingredients like isopropyl alcohol and propanol are ones to look out for. In shampoos, most alcohols behave as harsh cleansers and can be excessively drying and rough on the hair, leaving it frizzy and prone to breakage . In more severe cases, these ingredients can cause skin irritation and other allergic reactions .
Not all alcohols are bad, though. Some may even help your hair retain moisture. The more "fatty" alcohols such as cetyl alcohol or Cetearyl alcohol can help condition the hair shaft, leaving it soft and shiny .
You've probably heard a thing or 2 about parabens by now, the bad boys of the cosmetic world. Another preservative, parabens discourage bacteria growth (similar to formaldehyde) and are usually used to increase the shelf life of your shampoos and conditioners .
Parabens are known hormone disruptors, meaning they can disrupt your endocrine system. The sneaky buggers can mimic the hormone estrogen! .
Aside from messing with hormones, researchers have discovered links between parabens and cancer. They can increase the risk of skin cancer by leading to UV damage to the skin. Some studies suggest that parabens may be linked to breast cancer, as they have been found inside breast cancer cells .
Some types of parabens have also been found to lower sperm count and affect male reproductive organs . Best to avoid parabens where you can.
Sulphates are the sudsy pals that make your shampoo lather up when you start scrubbing. They're a total foam booster .
The most common ones you'll find in hair care products are sodium lauryl sulphate (SLS), sodium laureth sulphate (SLES), and ammonium lauryl sulphate .
The issue with sulphates is that they're a known skin irritant. And because they can penetrate our skin, they're even more likely to cause allergic reactions. If you have an already sensitive scalp or sensitive skin, you should check the ingredients of your hair products for sulphates .
Yes, some of us might want our hair to smell like roses, fresh grapes, or cedarwood. But the reality is, all a haircare company has to write on the shampoo bottle is 'fragrance'. They don't have to tell you what the nice smell is made of .
This is a problem because most synthetic fragrances are made with toxic chemicals that have been linked to cancer, birth defects, hormone disruption, asthma, and allergies .
While some fragrances can be natural, it's highly unlikely your shampoo has crushed citrus fruits inside. Fragranced cosmetic products tend to be more irritating, so go fragrance-free where you can.
A colour refresh with shampoo sounds way easier than getting the box dye out. But most synthetic colours are made from coal tar or petroleum — not great for the human body .
Coal tar is literally made from burning coal, and is a known carcinogenic. It has proven links to various forms of cancer, and can potentially cause neurological damage .
Other potentially harmful ingredients
There's a whole laundry list of other chemicals and synthetic ingredients you might find on your shampoo and conditioner bottles, and we're not going to make you read them all.
But a few others you should keep an eye out for include:
- Polyethylene glycols (PEGs)
- Retinyl palmitate
What causes hair loss?
There are a lot of factors that can influence hair loss, and the most common one is genetics. But hormonal changes, medication side effects, radiation therapy, stress, and certain hair treatments can all play a role .
The process of genetic hair loss starts with hormones: your androgen hormones affect your hair follicles, making them look smaller and finer. As hair falls out, the new hairs become so fine and small that they're hard to see, giving the appearance of baldness .
Aside from genetics, any of the above chemicals have the potential to contribute to hair fallout; either by irritating the scalp and causing breakage, or by disrupting hormones that are responsible for hair growth.
Ingredients to look for in shampoo
We can't control our genetics, but we can control what we put on our hair. Making an effort to steer clear of toxic ingredients can go a long way in minimising hair and scalp damage.
When looking for a new shampoo or conditioner, you want to keep an eye out for nourishing ingredients that are as natural as possible. Big hitters that the hair community swear by are:
- Sulphate-free formulas
- Coconut oil
- Jojoba oil
- Essential oils (instead of synthetic fragrances)
- Other plant-derived ingredients 
How to treat hair loss (and encourage hair growth)
If you're already experiencing hair loss, or are mid-way doing a bathroom cleanout and worried about the products you're using, we've got you covered.
The good news is, hair loss can absolutely be treated. Depending on where you're at, you might want to explore either prescription or non-prescription options.
If just you're dipping your toes in and want to boost hair growth without a prescription, check out Pilot's Hair Growth Kit. It includes everything your scalp needs to be its best self — Biotin Hair Gummies, Hair Growth Shampoo & Conditioner, and a Derma Roller — and can be used alongside other prescription treatments.
If things feel a bit more advanced, or you'd like a professional treatment plan, then Pilot's prescription hair loss treatment is ready and waiting. Get the non-judgemental support you need, while keeping or regrowing your hair.
Plus, the results speak for themselves — 83% of users keep their hair with this treatment and 66% experience hair regrowth .
The best way to look after your scalp is to stay informed, which is why you're here. Keep an eye on those ingredient labels and your follicles with thank you.
Photo credit: Getty Images