Cellulitis is a bacterial infection of the skin that is characterized by swelling, redness, tenderness and heat in the affected area, according to Mayo Clinic. Cellulitis most commonly affects the lower legs though it can appear anywhere on the body, including in tissues below the skin.
If cellulitis is left untreated, it can spread rapidly to the lymph nodes or bloodstream, causing life-threatening consequences, according to Mayo Clinic. In some cases a fever may accompany cellulitis. It is important to seek immediate medical attention for cellulitis when a rash and fever are present to prevent the spread of the infection. When the rash and swelling are present without a fever, medical attention should be sought within the same day.