Overview

Cellulitis (sel-u-LIE-tis) is a common, potentially serious bacterial skin infection. Cellulitis appears as a swollen, red area of skin that feels hot and tender. It can spread rapidly to other parts of the body. Cellulitis isn't usually spread from person to person.

Skin on lower legs is most commonly affected, though cellulitis can occur anywhere on your body or face. Cellulitis might affect only your skin's surface. Or it might also affect tissues underlying your skin and can spread to your lymph nodes and bloodstream.

Left untreated, the spreading infection can rapidly turn life-threatening. It's important to seek immediate medical attention if cellulitis symptoms occur.

Symptoms

Possible signs and symptoms of cellulitis, which usually occur on one side of the body, include:

  • Red area of skin that tends to expand
  • Swelling
  • Tenderness
  • Pain
  • Warmth
  • Fever
  • Red spots
  • Blisters
  • Skin dimpling

When to see a doctor

It's important to identify and treat cellulitis early because the condition can spread rapidly throughout your body.

Seek emergency care if:

  • You have a red, swollen, tender rash or a rash that's changing rapidly
  • You have a fever

See your doctor, preferably that day, if:

  • You have a rash that's red, swollen, tender and warm — and it's expanding — but without fever

Causes

Cellulitis occurs when bacteria, most commonly streptococcus and staphylococcus, enter through a crack or break in your skin. The incidence of a more serious staphylococcus infection called methicillin-resistant Staphylococcus aureus (MRSA) is increasing.

Although cellulitis can occur anywhere on your body, the most common location is the lower leg. Bacteria is most likely to enter disrupted areas of skin, such as where you've had recent surgery, cuts, puncture wounds, an ulcer, athlete's foot or dermatitis.

Certain types of insect or spider bites also can transmit the bacteria that start the infection. Bacteria can also enter through areas of dry, flaky skin or swollen skin.

Risk factors

Several factors can place you at greater risk of developing cellulitis:

  • Injury. Any cut, fracture, burn or scrape gives bacteria an entry point.
  • Weakened immune system. Conditions that weaken your immune system — such as diabetes, leukemia and HIV/AIDS — leave you more susceptible to infections. Certain medications, such as corticosteroids, also can weaken your immune system.
  • Skin conditions. Skin disorders — such as eczema, athlete's foot, chickenpox and shingles — can cause breaks in the skin and give bacteria an entry point.
  • Chronic swelling of your arms or legs (lymphedema). Swollen tissue may crack, leaving your skin vulnerable to bacterial infection.
  • History of cellulitis. People who previously had cellulitis, especially of the lower leg, may be more prone to develop it again.
  • Intravenous drug use. People who inject illegal drugs have a higher risk of developing cellulitis.
  • Obesity. Being overweight or obese increases your risk of developing cellulitis and having recurring episodes.

Complications

The bacteria that cause cellulitis can spread rapidly, entering lymph nodes and your bloodstream. Recurrent episodes of cellulitis may damage the lymphatic drainage system and cause chronic swelling of the affected limb.

In rare cases, the infection can spread to the deep layer of tissue called the fascial lining. Flesh-eating strep (necrotizing fasciitis) is an example of a deep-layer infection. It represents an extreme emergency.

Prevention

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

  • Wash your wound daily with soap and water. Do this gently as part of your normal bathing.
  • Apply a protective cream or ointment. For most surface wounds, an over-the-counter antibiotic ointment (Neosporin, Polysporin, others) provides adequate protection.
  • Cover your wound with a bandage. Change bandages at least daily.
  • Watch for signs of infection. Redness, pain and drainage all signal possible infection and the need for medical evaluation.

People with diabetes and those with poor circulation need to take extra precautions to prevent skin injury. Good skin care measures include the following:

  • Inspect your feet daily. Regularly check your feet for signs of injury so you can catch infections early.
  • Moisturize your skin regularly. Lubricating your skin helps prevent cracking and peeling.
  • Trim your fingernails and toenails carefully. Take care not to injure the surrounding skin.
  • Protect your hands and feet. Wear appropriate footwear and gloves.
  • Promptly treat infections on the skin's surface (superficial), such as athlete's foot. Superficial skin infections can easily spread from person to person. Don't wait to start treatment.

Cellulitis care at Mayo Clinic

Feb. 11, 2015
References
  1. Cellulitis. The Merck Manual Professional Edition. http://www.merck.com/mmpe/print/sec10/ch119/ch119b.html. Accessed Dec. 7, 2014.
  2. Baddour LM. Cellulitis and erysipelas. http://www.uptodate.com/home. Accessed Dec. 7, 2014.
  3. Keller EC, et al. Distinguishing cellulitis from its mimics. Cleveland Clinic Journal of Medicine. 2012;79:547.
  4. Barbara Woodward Lips Patient Education Center. Cellulitis. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2009.
  5. Skin care. American Diabetes Association. http://www.diabetes.org/living-with-diabetes/complications/skin-care.html. Accessed Dec. 8, 2014.