What Is It?

Cellulitis is a serious bacterial infection of the skin. In cellulitis, bacteria penetrate the skin’s protective outer layer, typically at the site of an injury, such as a cut, puncture, sore, burn or bite. Cellulitis also can occur at the site of surgery, or where the skin was punctured for a small plastic tube (IV catheter) used to administer medications. Once inside the skin, the invading bacteria multiply and produce chemicals that cause inflammation within the skin.

Cellulitis usually occurs on the legs and feet. However, it can develop on any part of the body, including the trunk, arms and face. It often develops near an area where there already is swelling, poor blood flow, or another skin condition such as a fungus infection between the toes (athlete’s foot).

Many different types of bacteria can cause cellulitis. However, most cases are caused by Streptococcus pyogenes (strep) or Staphylococcus aureus (staph). Other types of bacteria can cause infection after certain types of skin injuries, such as animal bites, puncture wounds through wet shoes and wounds exposed to freshwater lakes, aquariums or swimming pools.

Cellulitis can take several specific forms, including:

• Periorbital cellulitis, a skin infection around the eye sockets (orbits) — Often, this is caused by Haemophilus influenza (H. flu), a type of bacterial infection that is common in children. Since infection around the eye can spread to the brain, periorbital cellulitis requires prompt medical attention.



• Erysipelas, a form of skin infection that produces raised, firm, bright red patches of skin — Usually, it is caused by streptococcus bacteria. Erysipelas occurs most often on an arm or leg that has been damaged by previous surgery or is chronically swollen due to poor lymph flow (lymphedema). Erysipelas also can develop on the face, typically across the bridge of the nose and upper cheeks.



• Necrotizing fasciitis, also known as “flesh-eating strep” — This is an infection of the tissues below the skin, rather than the skin itself. Often, the overlying skin is discolored and extremely painful. Fasciitis is a life-threatening infection that requires prompt medical attention.

In cellulitis, the affected area of skin feels warm and usually is red, swollen and painful. The redness can be vague, or can stand out compared to surrounding skin. The area of warmth can be felt with the back of the hand, especially when compared to surrounding skin. There may be a spreading network of red streaks in the skin, caused by infection in the vessels that carry lymph (tissue fluid), as well as enlarged lymph nodes (swollen glands) near the area of infection.

Fever and malaise (a generally sick feeling) often accompany cellulitis. Severe infections can cause low blood pressure if bacteria get into the bloodstream. Bloodstream infections (blood poisoning) from cellulitis are particularly dangerous in the very young and very old, as well as those with weakened immune systems or abnormal heart valves.

Your doctor will ask you about how your cellulitis developed and your symptoms, including whether you have:

• Had recent injuries such as cuts, scrapes, bites or puncture wounds
• Previously injured the area or been operated on there
• Had unusual exposures such as fish tanks, pond water or animals
• Underlying medical problems that increase your risk for complications
• Shaking chills or other symptoms that suggest the infection has spread to the bloodstream or to surrounding organs

Many people who develop cellulitis have no underlying medical problems and no obvious injury or skin damage that allowed the infection to occur.

Your doctor can diagnose cellulitis based on the history of your injury, your symptoms and the results of a physical examination. If your skin wound is draining fluid or pus, your doctor may take a sample of wound drainage for tests to identify the type of bacteria and specific antibiotics to eliminate the bacteria.

How long cellulitis lasts depends on the type of skin injury, the bacteria that caused the infection, and your general health. Without proper antibiotic treatment, some forms of cellulitis can cause serious complications within a few days, even in otherwise healthy patients.

To help prevent cellulitis:

• Prevent skin injury — Wear protective gloves while gardening and working outdoors. Wear long sleeves and trousers while hiking, and avoid going barefoot outdoors. Wear protective padding on elbows and knees while skating.



• Treat minor skin wounds promptly — Gently wipe away any dirt, wash with antibiotic soap, apply antibiotic ointment and cover with a clean bandage.



• Seek medical attention for all deep puncture wounds and animal bites, and for all deep wounds involving a joint, hand or foot.

Cellulitis is treated with antibiotics. Your doctor will choose a specific antibiotic depending on the location of your cellulitis and the likely cause of your infection. Most cases of cellulitis improve quickly once antibiotics are given.

If you have mild cellulitis, you probably can be treated at home with antibiotics taken by mouth. However, you must keep in close contact with your doctor to be sure that the infection is improving as expected. At home, warm compresses, such as a warm, moist washcloth, and elevating the infected area can help. If you have severe cellulitis, you may need to be treated in the hospital with antibiotics given intravenously (into a vein).

Call your doctor whenever a skin injury becomes red, warm, swollen or tender. Call your doctor promptly if you get a deep puncture wound, especially on a hand or foot, or if you are bitten by an animal or human.

In most cases, symptoms of cellulitis begin to improve within 24 to 48 hours of starting treatment with appropriate antibiotics. You should always take all the antibiotics prescribed by your doctor, even if you think your infection has been cured.

Diseases and Conditions Center

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.