Cellulitis is a skin infection that usually affects the legs, feet, and arms. However, the infection can also occur within the eye sockets, around the eyes, and on the toes. Cellulitis is characterized by swelling, redness, warmth, and pain. The condition is caused by bacteria. The most common cause of cellulitis in adults with no other medical conditions is group A streptococcus, which is a bacterium commonly found in the throat and on the skin. Specific treatment for cellulitis includes medications, such as antibiotics, and prevention the infection from recurring.