Cellulitis (sel-u-LIE-tis) is a common, potentially serious bacterial skin infection. Cellulitis appears as a swollen, red area of skin that feels hot and tender. It can spread rapidly to other parts of the body. Cellulitis isn't usually spread from person to person. Skin on lower legs is most commonly affected, though cellulitis can occur anywhere on your body or face. Cellulitis might affect only your skin's surface. Or it might also affect tissues underlying your skin and can spread to your lymph nodes and bloodstream.