Question: Did you ever research the substances in shampoo? I did and discovered that most of the substances were irritant. Why do shampoos have such irritant substances, aren't they supposed to help?

Ruhina Miller answered on 18 Jun 2015:

A lot of useful substances are often classified as irritants/harmful/toxic. Often this is because the “pure” form does have these properties and it is not advisable get them in your eyes (sometimes on your skin) because they will have irritating effects such as redness. It is especially bad to eat them because this can have all sorts of effects.

In shampoos, the levels (concentrations) of these substances are not 100% (because you have many components) – so this can often dilute their irritating/harmful/etc effects. In the case where this is not so, other components can be added to make it safe to apply to your skin (however, a very small number of people may still “react” because they have sensitive skin); and many brands try and make it safer if you get it in your eyes as well (but still it’s good to avoid where possible). It is still NOT recommended to eat this. If you compare something like shampoo to laundry detergent – you wouldn’t use laundry detergent to clean your skin because the focus on this isn’t to make it “skin safe” compared to shampoos which you do directly apply to yourself.

So why do we use these irritating substances? Well as I said, a lot of useful substances have useful properties. The main one is surfactants – we need them to clean the oil/dirt off your hair, and to do this it has to be a *bit* aggressive. Stabilising agents may also be needed to help it to last longer.

At the end of the day the aim is to keep the components to a minimum, but even more important is to keep it safe and these products undergo extensive tests to ensure that they are safe for use! 🙂