Cellulitis

Cellulitis is a bacterial infection of the deeper layers of skin and the tissues beneath. It typically causes a red, hot, swollen, painful patch of skin that spreads over hours to days. Cellulitis can be mild or serious — it needs prompt antibiotic treatment, and severe cases need hospital care.

Causes

Bacteria (most often Staphylococcus or Streptococcus) enter the skin through:

• Cuts, scrapes, insect bites
• Surgical wounds
• Existing skin conditions — eczema, athlete's foot, fungal infection, ulcers
• Lymphoedema or chronic swelling
• Injected drug use
• Sometimes there's no obvious entry point

Risk factors

• Diabetes
• Poor circulation, venous insufficiency
• Weakened immunity
• Prior cellulitis (tends to recur in the same limb)
• Skin breaks, athlete's foot, chronic ulcers
• Obesity

Symptoms

• Red, warm, swollen, tender area of skin
• Spreading redness over hours to days
• Pain
• Skin may look tight and shiny
• Fever, chills, feeling generally unwell
• Swollen lymph nodes near the affected area
• Sometimes blisters, pus, or streaks of red spreading from the area

When to see a doctor

Any suspected cellulitis needs prompt medical attention. Go to hospital or dial 112 urgently for:

• Rapidly spreading redness
• High fever with the infection
• Severe pain out of proportion to what's visible (could signal a deeper, more serious infection)
• Cellulitis on the face, especially around the eye
• Signs of sepsis — confusion, fast heart rate, fast breathing, very unwell
• Cellulitis in a person with diabetes or weakened immunity

Treatment

• Antibiotics — oral for mild-to-moderate cellulitis, IV in hospital for severe cases or if oral treatment isn't working
• Elevate the affected limb to reduce swelling
• Rest the area
• Mark the edge of the redness with a pen — helps track whether it's improving or spreading
• Treat any underlying cause — athlete's foot, ulcers, lymphoedema

Prevention

• Keep skin clean and moisturised
• Clean and dress cuts, bites, and scrapes promptly
• Treat athlete's foot and other fungal infections (common entry point)
• Good foot care in diabetes
• Compression stockings for chronic leg swelling
• For people with recurrent cellulitis — long-term low-dose antibiotics and treating triggers