Quick answer
What is cellulitis?
Cellulitis is a bacterial infection of the deeper skin layers, causing a red, hot, swollen and painful area that spreads quickly. It needs antibiotic treatment — see a GP promptly. Call 999 if the redness spreads rapidly, you have a high fever with confusion, or red streaks appear — signs the infection may be spreading in the bloodstream.
What is cellulitis?
Cellulitis is a bacterial infection of the deeper layers of the skin. It causes a painful, red, hot, swollen area that typically spreads if not treated with antibiotics. Cellulitis can affect any part of the body but is most common on the lower leg. It is not the same as cellulite (cosmetic dimpling of skin).
Symptoms
Cellulitis usually develops over hours to days:
- an area of skin that is red, hot and swollen
- pain or tenderness — the area may feel tight
- skin that looks shiny or stretched
- the redness often has a spreading edge — it grows outward
- fever, chills and feeling generally unwell
- swollen glands near the affected area
The affected area may feel warm compared to surrounding skin.
How bacteria get in
Cellulitis happens when bacteria — usually streptococcus or staphylococcus — enter through a break in the skin:
- cuts, grazes and surgical wounds
- athlete’s foot — cracks between toes are a very common entry point on the leg
- insect bites
- eczema or dry cracked skin
- leg ulcers
- lymphoedema (chronic limb swelling)
It is rarely passed from person to person.
Treatment
Cellulitis needs antibiotics. See a GP promptly — do not wait to see if it clears on its own.
At home alongside antibiotics:
- Rest the affected area
- Elevate the limb above heart level to reduce swelling
- Paracetamol or ibuprofen for pain and fever
- Mark the edge of the redness with a pen — if redness spreads past the mark despite antibiotics, contact your GP urgently
Severe cellulitis needs hospital treatment with intravenous antibiotics.
Who is at higher risk
- people with diabetes
- weakened immune systems
- lymphoedema
- previous episodes of cellulitis
- intravenous drug use
These groups should seek same-day medical assessment.
Preventing recurrence
If cellulitis keeps returning:
- treat athlete’s foot aggressively and keep feet clean and dry
- moisturise dry skin to prevent cracks
- manage underlying conditions — diabetes, leg ulcers
- a GP may prescribe long-term low-dose antibiotics to prevent further episodes
When to seek emergency help
Call 999 if:
- redness spreads rapidly despite antibiotics
- high fever with confusion or drowsiness
- red streaks extending from the affected area (lymphangitis)
- severe pain, blistering, or blackening of skin
- you feel very unwell
These may indicate spreading infection (sepsis) or necrotising fasciitis — rare but serious.
Cellulitis vs other red skin conditions
Eczema and contact dermatitis cause red, itchy skin but are not usually hot, rapidly spreading, or accompanied by high fever. DVT (deep vein thrombosis) causes a swollen leg but without the same hot, spreading redness. When in doubt, see a GP the same day.
Common questions
- What does cellulitis look like?
- An area of skin that is red, hot, swollen and painful, often with a sharp or spreading edge. The skin may look tight and shiny. You may feel generally unwell with fever and chills. It commonly affects the lower leg but can occur anywhere.
- What causes cellulitis?
- Bacteria — usually streptococcus or staphylococcus — enter through broken skin. Cracks from athlete's foot, cuts, insect bites, eczema, and leg ulcers are common entry points. It is not usually spread from person to person.
- How is cellulitis treated?
- Antibiotics — tablets for mild cases, intravenous antibiotics in hospital for severe infection. Rest, elevation of the affected limb, and paracetamol for pain and fever. Mark the redness edge with a pen to monitor spread. Complete the full antibiotic course.
- How can I prevent cellulitis?
- Treat athlete's foot promptly, moisturise dry cracked skin, clean cuts and cover with a dressing, manage diabetes well, and treat leg ulcers under medical supervision. If you have recurrent cellulitis, a GP may recommend long-term preventive antibiotics.
- What is the difference between cellulitis and erysipelas?
- Erysipelas is a similar bacterial skin infection but affects the upper skin layers, often with a raised, clearly demarcated edge. Both need antibiotics. A doctor distinguishes them on examination — treatment is similar.