Cellulitis is an inflammation due to bacterial infection of the deep layers of the skin (the deep dermis and subcutaneous tissue). It can also spread to tissues underneath the skin or to the blood and lymph nodes.

The bacteria that cause cellulitis can enter the body through a cut, puncture wound or after surgery. Some risk factors for cellulitis include age, diabetes and alcoholism.

Cellulitis can occur on any part of the body, but it is most common on the legs and face. It differs from impetigo, which is a more superficial skin infection.

There are several types of cellulitis including preseptal cellulitis (inflammation of the eyelid), necrotizing cellulitis (a severe form of cellulitis characterized by death of infected tissue) and erysipelas (bacterial infection of the skin and tissue below the skin that affects the face, ears and lower legs).

Symptoms of cellulitis include a general sick feeling (malaise), red and inflamed skin and pain or tenderness in the affected area. Patients experiencing severe symptoms such as a high fever, significant pain or the inability to move a limb due to pain should seek immediate medical attention. 

Cellulitis is usually treated with antibiotics (medications that kill or slow the growth of harmful microorganisms, such as bacteria). They are usually taken orally. Symptoms typically disappear within a few days of starting the medication. Patients that do not respond to the initial treatment or have severe symptoms may require hospitalization and intravenous administration of antibiotics.

To prevent cellulitis, patients should wear protective equipment during work or sports to prevent breaks in the skin. Those with existing skin wounds should keep them clean and covered to avoid infection.