Shampoo vs. Soap

Soaps and bottles of shampoos covered in water drops.

Sharing a home with a husband and two teenagers, I regularly find myself staring at countless half-empty and empty bottles of shampoo and soap; they’re scattered all around the bathroom and in the shower. Why do we even need different products for our bodies and hair? Let’s have a closer look at shampoo vs. soap.

Although shampoo and soap share similarities like the same principle ingredients, they differ significantly in formula, target, and purpose. Shampoo can sometimes be used as soap, but it is advisable not to use soap as shampoo.

Did you know that soap bars can prevent foggy mirrors or that shampoo can act as shaving cream? Let’s find out more about these two substances:

Are Shampoo and Soap the Same?

Towels and liquid soaps over the bathroom counter.

Before we delve into whether shampoo and soap are the same, let’s have a quick look at their basic formulas.

The basic soap formula is potassium hydroxide (liquid soap) or sodium hydroxide (solid soap) and animal or vegetable fat. Sometimes, the potassium hydroxide is mixed with acetic acid.

A soap molecule has two functions: bonding to water and bonding to debris. On the one side, this bonding creates foam and lather, and on the other side, it rids our bodies of dirt and grime.

Soap is a surfactant, which means when it comes in contact with a liquid, it starts to increase its wetting and spreading properties.

Shampoo is also a surfactant but to a lesser extent. Subsequently, it removes fewer natural oils from your hair to keep it healthy.

The detergents in shampoo are produced by a different process than soap. The shampoo also contains specific conditioning molecules. These molecules are specifically attracting to the shafts of your hair, which is why your hair is smoother and softer after a wash.

So, shampoo and soap share ingredients like water and surfactants, but they are also vastly different. Let’s have a look at the similarities and differences between shampoo and soap.

What Are the Similarities Between Shampoo and Soap?

Woman hands with soapy foam bubbles.

Apart from the fact that shampoo and soap are both cleaning agents, they also share other similarities:

  • Most shampoos and soaps contain a surfactant called Sodium Laureth Sulfate (SLS). SLS mixes well with oil and easily rinses away with water.
  • Both come in bar or liquid form.
  • They act similarly in that they both have a water-attracting side and a water-repelling side.
  • Both can be either scented or unscented.
  • They can be colored or clear.

What Are the Differences Between Shampoo and Soap?

Woman in the bathroom with hands filled with soap bubble foam.

Although shampoo and soap are similar in some ways, they are also vastly different:

  • Shampoo is designed to clean your hair, while soap is designed to clean your face and body.
  • They contain different ingredients for different effects. Shampoo, for instance, has a moisturizing component, while soap doesn’t.
  • The surfactants in shampoo are not as harsh as in soap. According to Blair Murphy-Rose, a dermatologist from New York, surfactants remove oil, and for hair to remain healthy, soft, and shiny, some degree of natural oil needs to stay after a wash.
  • Soap has been in use long before shampoo. Astonishingly, ancient recipes for soap date back thousands of years. In 1927, Hans Schwarzkopf invented the first liquid version of shampoo as we know it today.

Can You Use Soap as Shampoo?

Woman washes her hair with a shampoo bar.

It’s not advisable to use soap as shampoo. Even natural soap can strip your hair from its essential oils.

Other reasons why you should rather lay low with the soap are the following:

  • Modern commercial soap bars contain much more than sodium hydroxide and fat. They can be loaded with fragranced oils, artificial colors, harmful chemicals, and other synthetic ingredients. The chances are good that washing your hair regularly with these bars will strip your hair of too much oil, leaving it dry and lifeless.
  • Soap bars and body washes are much milder than shampoos. They will be less effective in removing all sweat and dirt from your hair.
  • The natural pH of our hair is around 4.5 to 5.5. Using a soap bar or a body wash on your hair will create an imbalance; this imbalance can lead to dandruff, breakage, and frizz.

We’ve all been in situations where we had no choice but to use soap as shampoo, and once or twice won’t be that big a disaster. Nonetheless, you should not wash your hair with soap too often, but can you wash your face and body with shampoo?

Can You Use Shampoo as Soap?

Woman pouring shampoo from a dispenser.

Using shampoo as soap is safer than using soap as shampoo. Dr. Murphy-Rose states that ‘It should not be a big problem if you were to use a shampoo as a body wash just once in a while.’

The keywords are ‘once in a while,’ as using shampoo as soap also have some cons:

  • Shampoo has a higher pH than soap. Therefore, shampoo can create an imbalance in the skin’s natural pH levels. Especially people with sensitive skins and those who are prone to acne should be cautious.
  • Shampoo doesn’t contain glycerin, so it might leave your skin feeling stretched and dry.
  • The surfactant levels of shampoo are lower than that of soap and body washes. Subsequently, shampoo will be less effective in ridding your skin of dirt, debris, and oil.


Although shampoo and soap do share some similarities, we should not ignore their differences. If you want your skin and hair to stay as healthy as possible, don’t replace one with the other. I guess all those half-empty bottles will keep haunting me for quite a while still. But oh well, as long as we all stay clean and healthy.



Britannica: Surfactant

Well+Good: What Derms Want You to Know About Using Shampoo As Your Body Wash in a Pinch 

Stack Exchange: Soap versus Shampoo

Wonderopolis: How Is Shampoo Different Than Soap?


Stylecraze: Is It OK To Use Body Wash As Shampoo Or Vice Versa?

NCBI: Evaluation of pH of Bathing Soaps and Shampoos for Skin and Hair Care

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