It is an inflamed hair shaft (sometimes the pore is filled with pus) caused by a hair follicle grows back under the skin (ingrown hair). It is commonly associated with regular shaving. It is most commonly found on the beards of black males but also occurs on other areas of the body i.e. legs, pubic area and the scalp. Untreated, ingrown hairs can cause scarring, redness and swelling (its medical term is Pseudofolliculitis Barbae or PFB).