Patient information: Skin and soft tissue infection (cellulitis)

SKIN INFECTION OVERVIEW

Cellulitis is an infection of the skin and soft tissue of the skin. The infection is usually caused by bacteria that normally live on the skin, such as staphylococci ("Staph") or streptococci ("Strep"). The infection develops when there is a break in the skin, such as a wound or injury, which may be minor. This allows bacteria to enter the skin and grow, causing infection and swelling.

Most cases of cellulitis are mild and heal completely with antibiotic treatment. However, the infection can become severe and cause a bodywide infection if left untreated. It is important to seek medical care promptly if you could have a skin infection.

This topic discusses the symptoms and treatment of cellulitis. Other skin infections are discussed separately. (See "Patient information: Methicillin-resistant Staphylococcus aureus (MRSA)" and "Patient information: Animal bites".)

SKIN INFECTION RISK FACTORS

Certain conditions increase the risk of developing cellulitis. These include:

• Recent injury to the skin (a wound, abrasion, cut, recent shaving, or injection drug use)
• Swelling of the skin due to radiation therapy
• Current skin infection, such as athlete's foot or impetigo
• Accumulation of fluid (edema) due to poor circulation, heart failure, liver disease, or past surgery to remove lymph nodes
• Being overweight
• Chronic skin conditions, such as eczema or psoriasis

However, cellulitis can also develop in people who have no known risk factors. (See "Cellulitis and erysipelas".)

SKIN INFECTION SYMPTOMS

Cellulitis — The most common symptom of cellulitis is pain or tenderness. Other cellulitis symptoms can include swelling, warmth, and redness in a distinct area of skin (picture 1). These symptoms usually worsen and the redness may expand over the course of a few days. The skin is usually smooth and shiny rather than raised or bumpy. Fever and chills are not common.

The most common areas of the body for cellulitis to develop include the legs and the arms; it can also develop around the eye, on the abdominal wall, in the mouth, and around the anus. (See "Cellulitis following pelvic lymph node dissection" and "Postoperative cellulitis in breast cancer patients".)

Other skin infections — Other types of skin infections include abscesses, furuncles ("boils"), and carbuncles. These usually cause a collection of pus under the skin. (See "Skin abscesses, furuncles, and carbuncles".)

Skin that is raised, reddened, tender, and pus-filled may be caused by a skin infection known as methicillin-resistant Staphylococcus aureus (MRSA). This is discussed separately. (See "Patient information: Methicillin-resistant Staphylococcus aureus (MRSA)".)

DO I NEED TO BE EXAMINED?

There are many types and causes of skin infections, and it is important to know the most likely cause of the infection before beginning treatment. Using the wrong treatment could allow the infection to worsen. To ensure that the correct treatment is used, it is important to be evaluated by a healthcare provider.

SKIN INFECTION TREATMENT

Cellulitis treatment includes antibiotics as well as treatment of any underlying condition that led to the skin infection.

Elevate the area — Elevating the arm or leg above the level of the heart can help to reduce swelling and speed healing.

Keep the area clean and dry — It is important to keep the infected area clean and dry. You can shower or bathe normally, and pat the area dry with a clean towel. You can use a bandage or gauze to protect the skin, if needed. Do not use any antibiotic ointments or creams.

Antibiotics — Most people with cellulitis are treated with an antibiotic that is taken by mouth for one to two weeks. The "best" antibiotic depends upon your situation.

If the infection is severe, you may need to be hospitalized and treated with antibiotics given into a vein (IV).

It is important to take the antibiotic exactly as recommended and to finish the entire course of treatment. Skipping doses or ending treatment early could potentially allow the bacteria to become resistant and require longer treatment.

Time to heal — The swelling, warmth, and redness should begin to improve within one to three days after starting antibiotics, although these symptoms can persist for two weeks. If the reddened area becomes larger, more swollen, or more tender, call your healthcare provider. He or she may want to reexamine you to determine if further testing or an alternate antibiotic are needed.

SKIN INFECTION PROGNOSIS

In most cases, you will recover completely from an episode of cellulitis without any complications. If you have skin infection risk factors (see 'Skin infection risk factors' above, talk to your healthcare provider to determine if there are steps you can take to minimize the risk of infections in the future.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Methicillin-resistant Staphylococcus aureus (MRSA)
Patient information: Animal bites

Professional Level Information:
Cellulitis and erysipelas
Cellulitis following pelvic lymph node dissection
Necrotizing infections of the skin and fascia
Overview of diabetic infections of the lower extremities
Preseptal (periorbital) and orbital cellulitis
Pseudomonas aeruginosa skin, soft tissue, and bone infections
Soft tissue infections following water exposure
Postoperative cellulitis in breast cancer patients
Skin abscesses, furuncles, and carbuncles

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/ency/article/000855.htm, available in Spanish)

• National Institute of Allergy and Infectious Diseases

      (www3.niaid.nih.gov/topics/cellulitisErysipelas/)

• Kidshealth.org

      (http://kidshealth.org/parent/infections/bacterial_viral/cellulitis.html)

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