SKIN INFECTION OVERVIEW
Cellulitis is an infection of the skin and soft tissue of the skin. The infection is usually caused by bacteria, such as staphylococci ("Staph") or streptococci ("Strep") that are commonly present on the skin or inner surface of the nose or mouth of otherwise normal and healthy people. The infection develops when there is a break in the skin, such as a wound or injury, which may be minor or even unnoticed. This allows bacteria to enter the skin and grow, causing infection and swelling.
Many cases of cellulitis are mild and heal completely with antibiotic treatment. However, some cases of cellulitis can be severe and lead to generalized infection. Thus, it is important to seek medical care promptly if the infection is associated with fever, rapid worsening, other signs of progression or if you have other medical problems, such as diabetes.
This topic discusses the symptoms and treatment of cellulitis. Other skin infections are discussed separately. (See "Patient information: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics)" and "Patient information: Animal bites (Beyond the Basics)".)
SKIN INFECTION RISK FACTORS
Certain conditions increase the risk of developing cellulitis. These include:
●Recent injury to the skin (a wound, abrasion, cut, shaving, or injection drug use)
●Prior radiation therapy
●The presence of a fungal or viral skin infection, such as athlete's foot or chickenpox
●Accumulation of fluid (edema) due to poor circulation, heart failure, liver disease, or past surgery to remove lymph nodes
●Chronic skin conditions, such as eczema
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. These symptoms commonly worsen and the redness may expand over the course of hours or days. The onset of cellulitis may be gradual or sudden. Itching is not a typical symptom of cellulitis. The skin is usually smooth and shiny rather than raised or bumpy. However, occasionally in cases of cellulitis, blisters or small pimples may form in the skin.
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 "Breast cellulitis: Clinical manifestations, diagnosis, and management".)
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) (Beyond the Basics)".)
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 an evaluation by your healthcare provider as to the likely bacterial cause of cellulitis in your case.
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 — Resolution of fever and chills, if they were present, should occur within one to two days after starting antibiotic therapy. Local findings of 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.
Transmission to others — Most forms of cellulitis are not highly contagious to other family members. However, when you have cellulitis, it is important to wash your hands regularly with soap and water and to avoid sharing towels.
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.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Cellulitis and erysipelas (skin infections) (The Basics)
Patient information: Chronic granulomatous disease (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Methicillin-resistant Staphylococcus aureus (MRSA) (Beyond the Basics)
Patient information: Animal bites (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Cellulitis and erysipelas
Cellulitis following pelvic lymph node dissection
Necrotizing soft tissue infections
Clinical manifestations, diagnosis, and management of diabetic infections of the lower extremities
Pseudomonas aeruginosa skin, soft tissue, and bone infections
Soft tissue infections following water exposure
Breast cellulitis: Clinical manifestations, diagnosis, and management
Skin abscesses, furuncles, and carbuncles
The following organizations also provide reliable health information.
●National Library of Medicine
(www.nlm.nih.gov/medlineplus/ency/article/000855.htm, available in Spanish)
●National Institute of Allergy and Infectious Diseases