Cellulitis risk factors: skin breaks, swelling, weight and warning signs

What cellulitis is

Cellulitis is a common bacterial infection of the deeper layers of the skin. It causes redness, swelling, and pain in the infected area. If untreated, cellulitis can spread and cause serious health problems (CDC).

Different bacteria can cause cellulitis. Group A strep (streptococcal) bacteria are the most common cause (MedlinePlus). The bacteria enter your body when you get an injury such as a bruise, burn, surgical cut, or wound (MedlinePlus). In general, people cannot catch cellulitis from others (CDC).

Who is more likely to get cellulitis

Anyone can get cellulitis, but some factors can increase the risk of getting this infection (CDC).

Infections or injuries that break the skin

The CDC lists these risk factors, which allow bacteria to get through the skin (CDC):

• Chickenpox and shingles
• Chronic skin conditions (like athlete's foot and eczema)
• Injection drug use
• Injuries that break the skin, which can include cuts, ulcers, bites, puncture wounds, tattoos, and piercings

For many people who get cellulitis, experts don't know how the bacteria get into the body (CDC).

Other health factors

Other factors that increase risk for cellulitis include being overweight and chronic edema (CDC). Chronic edema is when limbs, like feet, legs, hands, or arms, stay swollen (CDC).

• Lymphedema can cause chronic edema. It happens when the lymphatic system doesn't drain the way that it should (CDC).
• A coronary artery bypass graft can also cause chronic edema. This surgery includes removing a healthy vein from the leg and connecting it to the coronary artery to improve blood flow to the heart (CDC).

Repeat infections

People who've had multiple cellulitis infections below the knee should be checked for fungal infections, and any infections found should be treated (CDC).

Signs of cellulitis

Generally, skin affected by cellulitis is painful, red, swollen, tender to the touch, and warm. The skin may look pitted, like the peel of an orange, and blisters may appear on the affected skin. Some people may also develop fever and chills (CDC). MedlinePlus also lists swollen glands or lymph nodes, and says the skin may blister and scab over (MedlinePlus).

Cellulitis can appear anywhere on the body, but it's most common on the feet and legs (CDC).

Complications

Complications from cellulitis are uncommon but can include serious infections (CDC):

• Bacteremia (bloodstream infection)
• Endocarditis (swelling of the heart's valves and inner lining)
• Osteomyelitis (bone infection)
• Suppurative arthritis (bacterial infection in a joint)

Cellulitis can also cause thrombophlebitis (swelling in a vein due to a blood clot) (CDC). Sepsis is the body's extreme response to an infection (MedlinePlus); see sepsis risk factors for who is most at risk and its warning signs.

Diagnosis and treatment

Healthcare providers typically diagnose cellulitis by looking at the affected skin during a physical examination. Blood or other lab tests aren't usually needed (CDC). Healthcare providers use oral antibiotics to treat most cellulitis infections, and IV antibiotics can be used to treat more serious infections. Keeping the affected limb (arm or leg) elevated can help decrease swelling and speed up recovery (CDC).

Common questions

Is cellulitis contagious?

In general, people cannot catch cellulitis from others (CDC).

Where on the body does cellulitis usually appear?

It can appear anywhere on the body, but it's most common on the feet and legs (CDC).

Why does swelling in the legs matter?

The CDC lists chronic edema, when limbs stay swollen, as a factor that increases risk for cellulitis. Lymphedema and a coronary artery bypass graft are two conditions that can cause it (CDC).