Acne skin can appear red, swollen and irritated. These reactions are the result of inflammation in the skin. The acne bacteria, Propionibacterium Acnes, causes the immune system to react by inducing inflammation and producing different kinds of chemicals, e.g. histamines and interleukins. Stress hormones can also trigger the release of histamine, which is produced in the inflammatory process, and can lead to redness and irritation of the skin. Soothing the skin by reducing inflammation is important.