Overview

Cellulitis (sel-u-LIE-tis) is a common and potentially serious bacterial infection of the skin. The affected skin is swollen and inflamed and is generally painful and hot to the touch.

Cellulitis usually affects the lower legs, but it can occur on the face, arms, and other areas. The infection occurs when a break in the skin allows bacteria to enter.

If left untreated, the infection can spread to the lymph nodes and bloodstream and quickly become life-threatening. It is generally not transmitted from person to person.

Symptoms

Cellulitis usually occurs on one side of the body. Signs and symptoms may include:

  • An irritated area of skin that tends to expand
  • Swelling
  • Tenderness
  • Pain
  • Heat
  • Fever
  • Chills
  • Spots
  • Blisters
  • Dimples in the skin

When to see a doctor

It is important to identify and treat cellulitis early because the condition can spread quickly throughout the body.

Seek emergency care if:

  • You have a swollen and tender rash or a rash that is changing rapidly
  • You have a fever

See your healthcare provider, preferably the same day, if:

  • You have a rash that is swollen, tender, and hot — and is expanding — but you do not have a fever

Causes

Cellulitis is caused when bacteria, most commonly streptococci and staphylococci, enter through a crack or break in the skin. The incidence of a more severe staphylococcal infection called Methicillin-resistant Staphylococcus aureus (MRSA) is increasing.

Cellulitis can occur anywhere on the body, but the most common location is the lower leg. Bacteria are more likely to enter broken, dry, scaly, or swollen skin, such as through a recent surgical site, cuts, puncture wounds, ulcers, athlete's foot, or dermatitis.

Risk factors

Several factors increase the risk of cellulitis:

  • Injury. Any cut, fracture, burn, or scrape provides an entry point for bacteria.
  • Weakened immune system. Conditions that weaken the immune system — such as diabetes, leukemia, and HIV/AIDS — increase the risk of infection. Certain medications can also weaken the immune system.
  • Skin conditions. Conditions such as atopic dermatitis (eczema), athlete's foot, and shingles can cause breaks in the skin, providing an entry point for bacteria.
  • Chronic (long-term) swelling of the arms or legs (lymphedema). This condition sometimes occurs after surgery.
  • History of cellulitis. Having had cellulitis before increases the risk of getting it again.
  • Being overweight. Excess weight increases the risk of developing cellulitis.

Complications

Untreated cellulitis could lead to bacteremia, endocarditis, osteomyelitis, toxic shock syndrome, or sepsis. Rarely, the infection can spread to the deep layer of tissue called the fascial lining. Necrotizing fasciitis is an example of a deep layer infection. It is an extreme emergency.

Recurrent episodes of cellulitis can damage the lymphatic drainage system and cause chronic swelling of the affected limb.

Prevention

If your cellulitis recurs, your healthcare provider may recommend preventive antibiotics. To help prevent cellulitis and other infections, take these precautions when you have a skin wound:

  • Wash the wound daily with soap and water. Do this gently as part of your normal bath.
  • Ask your healthcare provider if applying a protective cream or ointment would help. For most superficial wounds, an over-the-counter ointment (Vaseline, Polysporin, others) provides adequate protection.
  • Cover the wound with a bandage. Change bandages at least daily.
  • Watch for signs of infection. Irritation, pain, and pus are signs of possible infection and the need for medical care.

People with diabetes or poor circulation need to take extra precautions to prevent skin injuries. Good skin care includes the following:

  • Inspect your feet daily. Regularly check your feet for signs of injury so you can detect infections early.
  • Moisturize your skin regularly. Lubricating the skin helps prevent cracking and peeling. Do not apply moisturizer to open wounds.
  • Trim your fingernails and toenails carefully. Be careful not to damage the surrounding skin.
  • Protect your hands and feet. Wear appropriate footwear and gloves for your activities.
  • Promptly treat infections on the skin's surface, such as athlete's foot. Minor skin infections can easily spread from person to person. Treat fungal infections as soon as they occur.

Diagnosis

Your healthcare provider will probably be able to diagnose cellulitis by looking at your skin. You may need to undergo a blood test or other tests to help rule out other conditions.

Treatment

Treatment of cellulitis usually includes a prescription oral antibiotic. Within three days of starting an antibiotic, inform your healthcare provider if the infection is responding to treatment. You should take the antibiotic for the full course, usually 5 to 10 days, even if you start to feel better.

Symptoms usually disappear a few days after starting treatment. You may need to be hospitalized and receive antibiotics through your veins (intravenously) if:

  • Signs and symptoms do not respond to oral antibiotics
  • Signs and symptoms are extensive
  • You have a high fever

Self-care

Try these steps to help relieve any pain and swelling:

  • Place a cool, damp cloth on the affected area as often as needed for your comfort.
  • Ask your healthcare provider to suggest an over-the-counter pain medication.
  • Elevate the affected part of the body.
  • Ask your healthcare provider if compression wraps or stockings might help.

Preparing for your appointment

You will likely start by seeing your primary care provider, who may refer you to a doctor who specializes in skin disorders (dermatologist). If you have a severe infection, an emergency room doctor may examine you first. They may also refer you to an infectious disease specialist.

Here is information to help you prepare for your appointment.

What you can do

  • List your symptoms, including any that may seem unrelated to the reason you scheduled the appointment.
  • List key personal information, such as whether you have had recent surgeries, injuries, animal bites, or insect stings.
  • List medications, vitamins, and supplements you are taking and the dosage.
  • List questions to ask your healthcare provider.

Preparing a list of questions can help you make sure you cover points that are important to you. For cellulitis, some basic questions to ask your healthcare provider include:

  • How might I have gotten this infection?
  • What tests do I need? Do these tests require special preparation?
  • How is cellulitis treated?
  • How long before the treatment starts to work?
  • What side effects are possible with this medication?
  • I have other medical conditions. How do I manage them together?
  • Are there alternatives to antibiotics?
  • Is there a generic alternative to the medication you're prescribing?
  • How can I prevent this type of infection in the future?
  • Do you have brochures or other printed material that I can take? What websites do you recommend?

Don't hesitate to ask other questions you may have.

What to expect from your doctor

Your healthcare provider is likely to ask you questions like:

  • When did your symptoms begin?
  • Do you remember injuries or insect bites in that area?
  • How severe is the pain?
  • Is there anything that seems to improve your symptoms?
  • Are you allergic or intolerant to any antibiotics?
  • Have you had this type of infection before?

What you can do in the meantime

You may need a prescription antibiotic to clear up your infection. However, until you see your healthcare provider, you can wash the injured area with soap and water and place a cool, damp cloth over it.

Symptoms and Treatment of Cellulitis