When a product is advertised as being ‘soap’ free, it’s often Sodium Laureth Sulfate being referred to.
Basically a detergent and surfactant commonly used in most facial washes, it helps to remove surface dirt as well as act as a foaming agent, giving a product it’s lather.
Now, the problem with this ingredient can be that it causes irritation and from my experience in cosmetics the most common ingredient that people tend to react to. It can inflame dermatitis, psoriasis and eczema as it can break down the moisture barrier on the skin and ‘dry’ it out slightly. The reaction can present itself as itching, slight patches of dryness and sometimes redness; this is only in extreme cases however.
I personally prefer washes that contain this ingredient as for an oily combination skin type, its’ absolutely perfect as it can reduce surface oil and is a very effective cleanser.
There was concern a while ago that this ingredient could be carcinogenic, but these claims appear to have been dismissed. I think we may finally be getting over the media trend that seemed to scare us weekly with a barrage of cancer causes from fruit and vegetables to Facebook. The Guardian and Daily Mail being the biggest culprits.