Cellulitis is an infection of the skin and the soft tissue underneath, most often caused by bacteria that have entered from a cut, scrape or small crack in the skin. It is a common and, in some cases, potentially serious infection which can lead to hospitalization. Left untreated, the spreading infection can turn life-threatening.

According to the CDC, skin problems are the third-most frequent medical problem reported by returning travelers. It is estimated that each year two to three people per 100 are affected by cellulitis. It affects males and females equally, although a higher incidence of affected males has been recently reported.

Initially, the skin appears as a swollen, pink to red area that feels hot and tender to touch. It may also spread rapidly. Occasionally, red streaks radiate outward on the skin, and blisters or pus-filled bumps may be present. Cellulitis can also cause fever and swollen lymph nodes. Many people with cellulitis complain of feeling run-down or tired. The areas most commonly affected are the lower legs, although it can occur anywhere on your body or face, including your eyes.

Different types of bacteria can cause cellulitis. Most of the time, the offending bacteria are Streptococcus pyogenes, the same type that causes strep throat, and Staphylococcus aureus. Many staph bacteria live on our skin and do not cause any problems, but that is not the case with S. aureus: It is the most common bacteria causing staph infections.

Cellulitis can occur after an injury to the skin, an animal or insect bite, burn, puncture or a surgical wound. Sometimes there is no obvious cause or break in the skin. The chances for cellulitis increase with diabetes, circulatory problems, past surgery or radiation treatment of the legs or arms and chronic athlete’s foot. People with a weakened immune system due to medication or an underlying illness are also at risk. Certain skin disorders such as chicken pox, shingles and eczema cause breaks in the skin and place you at increased risk for cellulitis. It left untreated, cellulitis can develop into bacteremia, a bacterial infection in the blood.

Most cases of cellulitis improve with a single course of antibiotics for 14 days. Initially, the cellulitis may seem to get worse during the first few days of antibiotic therapy. This is because the bacteria release toxins when they are killed off by the antibiotics. If oral antibiotics do not work or if it is a very serious case, intravenous antibiotics may be necessary. Cellulitis used to be relatively easy to treat, but with the emergence of community-acquired methicillin-resistant S. aureus (MRSA), this is no longer true.

The reddened skin may be a signal of a more serious infection of the inner layers of the skin. Below your skin, the bacteria can spread quickly, entering the bloodstream through your lymph nodes. Repeated episodes of cellulitis can damage the lymphatic system, obstructing drainage and causing chronic swelling of the extremity. In rare instances, the infection can spread to the deep tissue called the fascial lining. Necrotizing fasciitis, also known as flesh-eating strep, is an example of a deep-layer infection. This represents an extreme emergency, and you must get to the nearest emergency room for treatment.

If you believe you have cellulitis, make an appointment to see your healthcare provider as soon as possible. While you are waiting to see your doctor, elevate the area to reduce swelling and apply a cool, moist compress to relieve pain. You need to start treatment with antibiotics to avoid complications. If you have fever and chills or if the cellulitis involves your face or eyes, you should go to the nearest emergency room.

Patients with diabetes should keep their blood sugar under control and speak to their doctors about proper foot care to prevent infection. Keep skin moisturized to prevent cracks and breaks in the skin. Wear shoes that fit well and provide enough room for your feet. Learn how to trim your nails to avoid harming the skin around them to prevent infection.

In most cases, symptoms improve within 24–48 hours of beginning antibiotic treatment. It is important to take the medication as prescribed and finish the entire course of medication, even if you start feeling better. Your doctor will also make sure that any underlying medical problems are being appropriately managed. The prognosis is usually good; but cellulitis can return, especially in individuals with poor circulation, chronic swelling of the legs, or skin that is not intact. Visit www.cdc.gov.

The content of this article is for informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.