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Cellulitis is a relatively common condition, and most often occurs in middle-aged and older adults. When comparing cisgender men and women, there is no statistically significant difference in the incidence of cellulitis, although some studies have reported higher incidences in cisgender men. There are approximately 50 cases per 1000 patient-years. 

To put these numbers into perspective, there were 21.2 million cases of cellulitis globally in 2015, with about 16,900 people dying from the condition that same year.

What is Cellulitis?

Cellulitis appears as a poorly demarcated (poorly defined) area of erythema (red patchy area). The affected area is often red and swollen while feeling hot, tender, and sometimes painful to the touch.

Cellulitis may also be associated with other symptoms of generalized malaise, such as fatigue, and fevers. Cellulitis can present in any area of the body, but most often affects the lower extremities. It is rarely bilateral (affecting both sides of the body).

Is this Condition Serious?

If cellulitis is not treated adequately, it may spread extensively and reach the lymphatic or circulatory systems. This spread may cause serious complications. Possible complications of cellulitis include:

  • lymphangitis (swelling, usually in one arm or leg),
  • abscess formation, and, rarely,
  • gangrenous cellulitis or necrotizing fasciitis (tissue death).

How is Cellulitis Diagnosed?

Most cases of cellulitis require medical attention.

Medical providers examine the affected area by looking and touching it. When gently palpating (examining) the affected area, medical providers can note any presence of warmth, tenderness, or purulent drainage (pus discharge). The presence of fluctuance—or, tense area of the skin with a boggy feeling upon palpation—could indicate the formation of an abscess.

Sometimes medical providers may request further diagnostic tests such as blood tests, culture, x-ray, ultrasound, or CT or MRI scans. These diagnostic tests can provide more information about the kind of bacteria causing the infection, the extension of the infection and can help rule out other conditions.

When examining a patient presenting with cellulitis, medical providers should take the complete medical history into account to evaluate for possible chronic medical conditions that predispose the patient to cellulitis, such as diabetes, venous stasis (slowed blood flow, most often in the legs), vascular (blood vessel) disease, chronic tinea pedis (long-term athlete’s foot), and lymphedema (swelling, most often in an arm or leg).

Medical providers should also take note of the context in which the patient noticed the skin changes or how the cellulitis began to occur. For example, it is important to take note of recent travels, recent trauma or injuries, history of intravenous drug use, or presence of insect or animal bites to the affected area. 

Although the portal of entry—or where the virus enters the body—is sometimes not distinct, medical providers should look for any area of skin breakdown. The affected area can be demarcated (clearly marked) with a marker to monitor if the infection spreads or regresses. 

How is this Condition Treated?

Sometimes, very mild cases of cellulitis may resolve themselves in a few days. Most often, though, cellulitis requires oral antibiotics. Symptoms of cellulitis fortunately most often start to ease two to three days after starting antibiotics. However, patients must complete the entire cycle of antibiotics prescribed by their medical providers.

More severe cellulitis may require intravenous antibiotics, meaning these patients must be admitted to hospital. 

Some people are at risk of recurring cellulitis. In particular, those with:

  • dry or flaky skin,
  • skin conditions such as eczema, shingles, or athlete’s foot,
  • immunodeficiencies or have an immunosuppressive disease,
  • poor blood circulation or lymphedema, or
  • intravenous drug use.

History of Cellulitis

Most experts date the first known use of the term cellulitis in the mid-nineteenth century, being derived from the Latin term cellula (small cell), with the suffix -itis denoting inflammation.

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