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InfectiousICD-10: L03.90Affects approximately 14.5 million cases annually in the United States

Cellulitis

Also known as: Skin Infection, Bacterial Skin Infection, Soft Tissue Infection

Cellulitis is a common and potentially serious bacterial skin infection that affects the deeper layers of the skin (dermis and subcutaneous tissue), most frequently caused by Streptococcus and Staphylococcus bacteria. The infection typically appears as a red, swollen, warm, and tender area of skin that spreads rapidly, most commonly affecting the lower legs. Without prompt antibiotic treatment, cellulitis can spread to the lymph nodes and bloodstream (sepsis), becoming life-threatening.

Symptoms

Red, swollen area of skin that feels warm and tender
Pain or tenderness in the affected area
Rapidly expanding redness or streaking
Fever and chills
Skin dimpling or pitting resembling an orange peel
Blisters or skin breakdown in severe cases
Swollen lymph nodes near the infection
General malaise and fatigue

Causes

  • Bacterial entry through breaks in the skin (cuts, scrapes, surgical wounds)
  • Streptococcus pyogenes (Group A Strep) and Staphylococcus aureus infection
  • Insect bites, animal bites, or puncture wounds
  • Skin conditions such as eczema, athlete's foot, or dermatitis creating entry points

Risk Factors

  • Breaks in the skin from cuts, wounds, or surgical sites
  • Weakened immune system from diabetes, HIV, or immunosuppressive medications
  • Chronic swelling of the legs (lymphedema) or poor circulation
  • Obesity
  • History of previous cellulitis episodes
  • Intravenous drug use

Diagnosis

  • Clinical examination of the affected skin area
  • Blood tests including complete blood count and blood cultures if systemic infection is suspected
  • Wound culture or skin biopsy in atypical or treatment-resistant cases
  • Ultrasound to rule out deep vein thrombosis or abscess formation

Treatment

  • Oral antibiotics (cephalexin, dicloxacillin, or amoxicillin-clavulanate) for mild cases
  • Intravenous antibiotics for severe or rapidly progressing infections
  • Elevation of the affected limb to reduce swelling
  • Pain management with over-the-counter analgesics
  • Surgical drainage if an abscess is present
  • Treatment of underlying skin conditions to prevent recurrence

Prevention

  • Clean and bandage all cuts, scrapes, and wounds promptly
  • Moisturize skin regularly to prevent cracking and dryness
  • Treat fungal infections such as athlete's foot to eliminate entry points
  • Wear protective footwear and gloves when appropriate
  • Manage chronic conditions like diabetes and lymphedema

When to See a Doctor

  • You notice a rapidly spreading red, warm, and painful area of skin
  • You develop fever, chills, or red streaking from a wound or skin infection
  • An area of redness does not improve within 48 hours of starting antibiotics
  • You have diabetes or a weakened immune system and suspect a skin infection

Frequently Asked Questions

Related Conditions

Eczema

Dermatological

Type 2 Diabetes

Endocrine

Obesity

Metabolic

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Medical Disclaimer: This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.

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