Sensitive skin is generally used to describe skin with reduced tolerance to the application of cosmetics and skincare products. Sensitive skin is caused by nerve endings in the top layer of skin becoming irritated often resulting in rashes or redness. This occurs because your skin’s natural barrier function is weakened and has broken down due to triggers. Some of these triggers can be certain ingredients in skincare products. Products designed for sensitive skin will often not have many ingredients in them, contain simple ingredients and not have any fragrances.