Overview
Cellulitis (sel-u-LIE-tis) is a spreading skin infection, most commonly of the lower leg. It's caused by bacteria entering through a break in the skin.
The affected skin is swollen, painful and warm to the touch. The infection can cause a fever and become very serious, involving deeper tissues.
The condition often clears up with antibiotic medicine.

Cellulitis
Cellulitis is usually an infection of the skin (left). But if the condition is severe or left untreated, as in the photo on the right, it can spread into tissue under the skin, the lymph nodes and the bloodstream.
Symptoms
Cellulitis is a common condition that can occur anywhere on the body, but it often involves the lower leg and usually just one side of the body.
Cellulitis symptoms include:
- Swelling.
- Warmth.
- Pain.
- Fever.
- Chills.
- Spots on the skin.
- Blisters.
- Skin dimpling.
When to see a doctor
It's important to find and treat cellulitis early because the condition can spread rapidly throughout the body.
Seek emergency care if:
- You have a swollen rash or a rash that's changing rapidly.
- You have a fever.
See a healthcare professional within 24 hours if you have a swollen rash or a rash that's growing but you don't have a fever.
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Causes
Cellulitis happens when bacteria enter the body through a crack or break in the skin. Bacteria are most likely to enter broken, dry, flaky or swollen skin. Examples of entry points for bacteria are a recent surgical site, a cut, a puncture wound, a sore, and skin affected by athlete's foot or dermatitis. Cellulitis usually isn't spread from person to person.
The most common bacteria with this condition are streptococcus and staphylococcus. The incidence of a more serious staphylococcus infection called methicillin-resistant Staphylococcus aureus (MRSA) is increasing.
Risk factors
Several factors put you at increased risk of cellulitis:
- Injury. Any cut, fracture, burn or scrape gives bacteria an entry point.
- Weakened immune system. Conditions that weaken the immune system increase the risk of infection. Examples are diabetes, leukemia and HIV/AIDS. Certain medicines also can weaken the immune system.
- Skin conditions. Conditions such as atopic dermatitis — also called eczema — athlete's foot and shingles can cause breaks in the skin and give bacteria an entry point.
- Long-term swelling of the arms or legs. This condition is called lymphedema. It sometimes happens 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 might lead to serious conditions such as 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's an extreme emergency.
Repeated episodes of cellulitis may cause the lymph nodes to enlarge. This can cause long-term swelling of the affected limb.
Prevention
If you tend to have repeated episodes of cellulitis, your healthcare professional may recommend taking antibiotic medicine to prevent it from coming back.
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 regular bathing.
- Ask your healthcare professional whether it would help to apply cream or ointment. For most minor wounds, the products you can buy without a prescription provide good protection. One example is petroleum jelly (Vaseline).
- Cover the wound with a bandage. Change bandages at least daily.
- Watch for signs of infection. Irritation, pain and pus all signal possible infection and the need for medical care.
People with diabetes or poor circulation need to take extra care to prevent skin injury. Good skin care includes the following:
- Inspect your feet daily. Check your feet for signs of injury so that you can catch infections early.
- Moisturize your skin at least once a day. This helps prevent the skin from cracking and peeling. Don't apply moisturizer to open sores.
- Trim your fingernails and toenails with care. Try not to cut the surrounding skin.
- Protect your hands and feet. Wear footwear and gloves suitable to your activities.
- Treat athlete's foot and toenail fungal infections as soon as they occur.