Cellulitis
Cellulitis is a bacterial infection of the deeper layers of the skin and underlying tissues. It usually starts at a break in the skin and can spread quickly if untreated.
Table of Contents
Quick Facts
- Type: Bacterial skin infection
- ICD-10: L03
- Common location: Lower legs (adults), face (children)
- Main treatment: Oral or IV antibiotics
Overview
Cellulitis is an infection of the skin and the tissue just beneath it, most often caused by Streptococcus or Staphylococcus bacteria. It typically appears as an expanding area of warm, red, swollen, painful skin and may be accompanied by fever and chills.
While many cases respond well to oral antibiotics, severe or rapidly spreading infections may need intravenous treatment in the hospital.
Symptoms
- Redness of the skin that expands over hours to days
- Swelling, warmth, and tenderness in the affected area
- Pain
- Skin dimpling (like orange peel)
- Fever and chills
- Swollen lymph nodes near the infection
- Blistering or pus drainage in severe cases
The lower legs are affected in most adult cases, but cellulitis can develop anywhere on the body.
Causes
Cellulitis develops when bacteria enter through a break in the skin. Common entry points include:
- Cuts, scrapes, or surgical wounds
- Insect bites or animal bites
- Cracks in dry skin or between toes (often from athlete's foot)
- Skin ulcers (e.g., from poor circulation or pressure)
- Recent skin procedures or IV insertion sites
Most cases are caused by Streptococcus pyogenes or Staphylococcus aureus, including MRSA in some cases.
Risk Factors
- Previous episode of cellulitis (recurrence is common)
- Chronic skin conditions (eczema, psoriasis, athlete's foot)
- Lymphedema or poor circulation
- Diabetes
- Weakened immune system
- Obesity
- IV drug use
Diagnosis
Cellulitis is usually diagnosed clinically based on appearance and symptoms. Tests may include:
- Blood tests (white blood cell count, inflammatory markers)
- Blood cultures if systemic infection is suspected
- Wound culture if there is pus or drainage
- Imaging (ultrasound, MRI) to rule out abscess or deeper infections like necrotizing fasciitis
Treatment
Antibiotics
Most cases are treated with oral antibiotics for 5–14 days. Severe infections — those with high fever, rapid spread, or involvement of the face — usually require IV antibiotics in a hospital setting.
Supportive care
- Elevate the affected limb to reduce swelling
- Pain relievers (acetaminophen, ibuprofen)
- Drain any abscess (small surgical procedure if needed)
- Treat underlying problems (e.g., athlete's foot, edema)
Follow-up
Mark the edge of the redness with a pen — if it expands past the line despite treatment, return for medical reassessment.
Prevention
- Clean cuts and scrapes thoroughly; cover them with a clean bandage.
- Treat athlete's foot and other fungal infections promptly.
- Moisturize dry skin to prevent cracking.
- Protect the legs and feet, especially if you have diabetes or poor circulation.
- Manage lymphedema with compression and skincare.
When to See a Doctor
Seek same-day care for:
- Redness, swelling, and pain that is expanding
- Fever or chills with a skin infection
- Facial cellulitis, especially near the eye
- Cellulitis in a person with diabetes or a weakened immune system
Go to the emergency department for severe pain out of proportion to the appearance, skin that turns purple or black, large blisters, or rapidly spreading redness — these can indicate a deeper, life-threatening infection (necrotizing fasciitis).
Frequently Asked Questions
Cellulitis itself is not usually contagious from skin-to-skin contact. However, the bacteria that cause it can spread, particularly if there is open wound drainage.
Symptoms usually start improving within a few days of antibiotics. The redness may take 1–2 weeks to fully fade. Always finish the full prescribed course of antibiotics.
Recurrent cellulitis is common in people with chronic swelling (lymphedema), poor circulation, or persistent skin conditions like athlete's foot. Treating the underlying problem can reduce recurrences.
Mild infections may occasionally resolve, but cellulitis can progress rapidly and cause serious complications. Antibiotics are the standard of care — don't wait to see if it gets better.
Cellulitis is a diffuse infection of skin tissue; an abscess is a localized collection of pus. The two can occur together. Abscesses usually require drainage in addition to antibiotics.
References
- Infectious Diseases Society of America. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections.
- Centers for Disease Control and Prevention. Cellulitis: All You Need to Know.
- Mayo Clinic. Cellulitis — Symptoms and causes.