Cellulitis is an infection of the deep layers of the skin. It develops when bacteria enter through a cut, bite, or wound — including tiny breaks in cracked, dry skin. Common skin-dwelling bacteria, Staphylococcus or Streptococcus, are the usual culprits. Although cellulitis can occur anywhere on the body, the most common location is the lower leg.

Dr. Arash Mostaghimi, a dermatologist at Brigham and Women’s Hospital and associate professor of medicine at Harvard Medical School, weighs in on new research that explores important questions about how long it takes to fully heal.

What are the symptoms of cellulitis?

The body’s natural immune response to this bacterial invasion triggers a painful rash that appears red on lighter skin and dark purple on darker skin. The affected area also may be swollen and feel warm.

How is cellulitis treated?

The typical treatment is five to 10 days of antibiotic pills. More serious cases may require intravenous antibiotics.

How quickly can antibiotics help cellulitis resolve?

After starting antibiotic treatment, people usually notice improvement within a few days. However, the area may remain swollen, warm, and painful even after 10 days.

Does that mean the antibiotic treatment was ineffective? Not necessarily, according to a recent study of people with cellulitis in the lower leg that described the natural history of the healing stages following antibiotics.

“The healing process has two parts, which is why a full recovery takes longer than you might think,” says Mostaghimi.

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