Cellulitis is a common bacterial skin infection causing redness, swelling, warmth, and pain; severe cases may spread rapidly and require urgent care.

Infectious Diseases

Cellulitis

2025-09-15

Intro

Cellulitis is a bacterial infection of the skin and soft tissues. It is common, but if untreated can spread quickly and become life-threatening.

Key Points

Classic signs: redness, swelling, warmth, pain, sometimes fever.
Usually caused by streptococci or staphylococci.
Rapid progression or systemic illness needs urgent care.
Treatment: antibiotics; sometimes drainage of abscesses.
Recurrence is common in chronic swelling or skin barrier disease.

Background

Skin provides a barrier against infection. When bacteria enter through breaks, cellulitis develops in the dermis and subcutaneous tissues.

Causes or Mechanisms

Group A Streptococcus (Strep pyogenes) and Staphylococcus aureus are most common. MRSA is a concern in some settings.

Diagnosis / Treatment / Options

Diagnosis: clinical (red, hot, swollen area); labs/imaging in severe/atypical cases.
Treatment: oral or IV antibiotics depending on severity; pain control; elevate limb; drain abscesses if present.

Risks / Benefits / Prognosis

Most people recover with antibiotics. Severe or untreated cellulitis can lead to sepsis, necrotizing infection, or chronic recurrence.

FAQ

Q: Can I prevent cellulitis?
A: Yes — treat athlete’s foot, moisturize skin, avoid trauma, and manage swelling/lymphedema.