Cellulitis is an infection of the skin. It can result from a burn, bite, or break in the skin, or may arise without any known injury. Symptoms of cellulitis may include increased swelling, redness, tenderness, and warmth in the area, which may also be accompanied by flu-like symptoms, nausea, or vomiting. It is important to contact a healthcare provider right away, as cellulitis requires treatment with antibiotics.