Dishwashing liquids aren’t the same as shampoos. The consistencies are different, so is the foamability, plus the fact that dermatologists advise that you wear gloves when using one of them in case it dries out your skin.

Unlike the bad science being pushed on social suggests, the ingredients in these two products are not the same. Here’s are some shampoo formulation examples  from a cosmetics ingredient manufacturer. Now here’s one for dishwashing liquid.
As you can see, different ingredients. For one, most dish detergents are formulated with sodium lauryl sulfate. This ingredient is their primary surfactant, the one that does the heavy duty cleaning work.

Sodium lauryl sulfate shampoos are now extremely rare thanks to the anti-sulfate campaign, which rightly got formulators to swap them for the gentler sodium laureth sulfate.

Dishwashing liquid almost always contains another potentially drying ingredient: sodium chloride (salt). Other common ingredients include SD alcohol and cocamide DEA – which isn’t compatible with certain haircare ingredients.

​The concentrations of the main surfactants are also different. Dishwashing liquids have more heavy duty cleaning to do, so they contain a higher amount of surfactant than shampoo.

Then there’s the fact that there’s A LOT of variability in the shampoo category. Unlike dish detergents, which tend to have more or less straightforward formulas, shampoo formulations vary widely.

Shampoo ingredients vary based on their purpose. Clockwise from top left: Halka Baba De Caracol Sulphate-Free Shampoo is for mild to moderate cleansing; atrActiva Anti-Stress Shampoo is a deep cleanser; Silicon Mix Shampoo is a moisturising cleanser; Capilo La Aplanadora Shampoo is deep-cleansing.

When it comes to dish detergent, you’ll find that many formulas are pretty much the same across brands. Cheaper ones will contain more water, but there’s far less variability overall.

This isn’t a huge surprise. After all, dish detergents are built to wash dishes, which are way less complicated and variable than hair. Most dishwashing liquids follow the same simple formula: primary surfactant, secondary surfactant, thickener, pH adjuster, hydrotrope, preservatives and water.

​Certain Instagrammers urging people to try dishwashing liquid have declared one brand superior to the others. They claim it’s gentle because it’s been used on rescued ducklings to remove crude oil after oil spills. But that doesn’t make it gentle enough to use as shampoo – and there’s no indication of the manufacturers ever advising people to use their product in this way.
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​While some innovative formulas do contain conditioning ingredients to make them softer on your hands, or different surfactants to make them more environmentally friendly, there’s a limit to how gentle dishwashing liquid can be and still be good at its job. If it wasn’t harsh enough to lift the grime off greasy pots and pans nobody would buy it.​This is why even dishwashing liquids that are marketed as safer – milder and more ecofriendly – are still much more concentrated than even a clarifying shampoo.
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The effects of using such a strong cleanser on your hair happen at a microscopic level so don’t expect to see most changes right away, unless your hair is very damaged or sensitive. The effects are cumulative though, so you will begin to see the impact on your hair after using it a few times.

Just so you can make your own informed decision on whether to use it or not, here’s exactly what happens when you use a typical dishwashing liquid to wash your hair:
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This is the most obvious ill effect. Sodium lauryl sulfate is an extremely powerful cleanser. It’s great at dissolving all kinds of oils – including the ones that keep your skin and hair moisturised. Once it rips away these natural moisturising lipids, your skin loses hydration rapidly. ​

​Because it usually contains sodium lauryl sulfate, dishwashing liquid can exacerbate dry scalp, leaving it flaky and irritated. And if you have an oily scalp, your sebaceous glands may start to overcompensate for the huge loss of sebum – and give you even more oiliness to deal with.
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The salt in dish soap (used as a cheap way to thicken the formula) will also seriously dry out your hair. Anyone who’s ever been to the beach knows salt air alone is enough to leave your hair looking like tumbleweed – and a dip in the sea without preparing your hair adequately can leave it dehydrated for weeks after.Then there’s the SD alcohol in some dish detergents: it’s highly astringent so dissolves your natural oils with ease.  If there’s enough in the formula, it could also swell your strands till they fracture.

Your cuticle’s job is to protect the inner layers of your hair. But did you know that there’s a layer on top of the cuticle that protects the cuticle itself? That’s your epicuticle, and it’s made up mostly of lipids, which provide a chemical surface barrier for your hair. 

​Since it’s so good at breaking down oils, using sodium lauryl sulfate regularly will eventually completely remove this protective layer. Once it dissolves the epicuticle, it gets to work dissolving the entire cuticle, including the cell membrane complex –  the  ‘glue’ that holds your hair together.
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The main ingredient in most dish detergents is so irritating that scientists regularly use it to trigger contact dermatitis for experimental purposes.
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When used to wash hair, sodium lauryl sulfate has been shown to set off another skin condition: atopic dermatitis.  It turns out  the salt in dish detergent isn’t just drying: mixed with the sodium lauryl sulfate in the formula it becomes a serious irritant.  The problem is rinseability: these formulas rinse pretty easily off of dishes. Rinsing it off a human being is another  story. ​

​As soon as the sodium lauryl sulfate-salt combination gets in contact with keratin – the stuff your hair and the outer layers of your skin are made of – it sticks to it. That’s creepy, but also pretty ironic, considering that the social media users who push dishwashing liquid think they’re getting their hair cleaner. In reality, they’re actually creating more buildup. 

This is bad for your hair, but it’s the consequences for your skin and body that are most worrying. The fact that you can’t rinse dishwashing liquid off fully means it has more time to stay on your skin and potentially cause irritation.

The safe level for sodium lauryl sulfate in leave on products is very low; 1%. The level in dishwashing liquid is several times that. If the residue it leaves behind exceeds that 1% concentration, or you use this stuff repeatedly and it starts to accumulate on your skin, it could potentially be toxic.
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Sodium lauryl sulfate loves to form complexes with the metal ions that hang out in hard water. This creates more buildup, aka surfactant residue, which sits on your hair, slowly dissolving your strands, even when you’re not shampooing.

​The damage this causes leads to chronic breakage, which could get in the way of your hair growth goals, as well as worsening  other problems with manageability and shine. The residue sits on your scalp too, causing dryness and potential irritation. ​

There is a third type of buildup dish detergent can create on your hair. Washing up liquid can get all the way into your strands; its main cleanser is small enough to actually penetrate the hair fibre.

Not only does sodium lauryl sulfate essentially break into your hair; the accomplices it recruits to join its efforts are pretty shocking – your conditioners.
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​After clarifying your hair, your strands will be extremely thirsty and in need of a good conditioner. But that’s exactly what you shouldn’t give your hair if you’ve just washed it with dishwashing liquid.

​Most modern conditioners contain cationic surfactants – ingredients with a high positive charge that are designed to bind to your hair’s surface. Most dishwashing liquids contain sodium lauryl sulfate, a strongly anionic (negative) surfactant.

When you go back and forth between a surfactant with a strong negative charge and one with a strong positive charge, you run into a problem.

​The strong opposite charges do what opposites usually do: they attract. Dishwashing liquid’s surfactant grabs your conditioner’s surfactant and drags it inside your hair.

​Together, they form a cationic-anionic complex inside your strand. Now you have something inside your strands that’s probably worse than the buildup you were trying to remove when you broke out the dishwashing liquid. ​

​This buildup is insoluble, so it’s hard to rinse out and even trying to wash it out with the strongest detergent you can find is only going to make bad matters worse. The more you do that, the more this independent layer of residue builds up inside your hair shaft.Once it gets high enough, it starts to make your strands swell and buckle,  and scale lifting starts to happen. This is when your cuticle gets peeled back from the inside out. It’s the beginning of crazy breakage for those strands.

If dish detergent does all of this destructive stuff to your hair, can there ever really be a good reason to use it?

​There are a couple of scenarios where dishwashing liquid might be your only or best option to remove something extremely tenacious from your strands. Make no mistake: your hair will take a hit for using it, but as a one-off under extreme circumstances, it might be worth it:

​Like on extremely greasy hair. We’re not talking the levels of grease your scalp can produce, even if you left it unwashed for months. But say  a slicked-back style attempt with large amounts of pomade, beeswax or Vaseline goes horribly wrong. ​

Another time where dishwashing liquid could come in very handy is in a dye job removal emergency.

​Say you dyed your hair, the colour didn’t come out as expected and now you can’t bear to look at yourself in the mirror. If you move quickly, you can probably get most of the colour out – by washing your hair several times with dishwashing liquid, immediately. The dish soap’s surfactants get all inside the hair strands and basically drag the colour molecules out for you. ​

​In either of these scenarios, bear in mind that dishwashing liquid is going to damage your hair if you decide to use it. And as dry and thirsty as your hair might feel afterwards, using conditioner could make bad matters worse.Outside of these two predicaments, there’s no logical reason to ever use dishwashing liquid to wash your hair. You can get seriously filthy hair clean with a clarifying shampoo based on sodium laureth sulfate, which doesn’t react so crazily to salt, cations or hard water – and it’s way gentler on your hair and skin. Try atrActiva Anti-Stress Shampoo and you’ll see what we mean.
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That takes us to the main reason why you shouldn’t be using dishwashing liquid to wash your hair: the safety testing. Many people don’t realise this, but cosmetics are more heavily safety tested than food. Household products that are not intended to be used on the body do not go through anywhere near such rigorous testing, and that includes dish detergent.

So even if you’re currently sporting the worst hair colour mistake possible or you accidentally emptied a whole tin of pomade onto your hair, you should probably think twice about using dish detergent to wash your hair.

​For the safer way to wash your hair, check out our washday guide.​