Skin

Cellulitis: Complete Guide

Cellulitis is a common bacterial skin infection that can spread rapidly and, in severe cases, lead to sepsis if not treated promptly.

Common cause
Streptococcus or Staphylococcus bacteria
Common sites
Legs (most common), face, arms
Treatment
Antibiotics — oral or IV depending on severity
Emergency sign
Rapid spread, systemic illness

Symptoms

Entry Points for Infection

Treatment

SeverityTreatment
Mild-moderateOral antibiotics (flucloxacillin typically first-line) for 5-7 days
Severe or spreading rapidlyIV antibiotics, often requiring hospital admission
Recurrent cellulitisInvestigation for underlying cause (chronic venous insufficiency, lymphoedema); sometimes long-term low-dose antibiotic prevention
Signs of Serious/Spreading InfectionRapidly spreading redness, severe pain out of proportion to appearance, purple/black discolouration, blistering, or fever with feeling very unwell can indicate a more serious infection (necrotising fasciitis) or sepsis — this requires emergency assessment.
Mark the EdgesIf starting antibiotic treatment for cellulitis, draw a line around the edge of the redness with a pen and note the date/time — this helps you and your doctor track whether the infection is spreading despite treatment, which would need urgent reassessment.
Is cellulitis contagious?
Generally no — cellulitis itself (infection within the skin and underlying tissue) isn't typically spread person-to-person through casual contact, unlike some surface skin infections.
Why does cellulitis keep coming back for some people?
Recurrent cellulitis is often linked to an underlying predisposing factor — chronic leg swelling (lymphoedema, venous insufficiency), obesity, or skin conditions that create repeated entry points for bacteria. Addressing these underlying factors reduces recurrence.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.