Cellulitis: Pictures, Symptoms, Causes & Treatment
Cellulitis is a bacterial infection of the deeper layers of the skin and the fat beneath it. Unlike a surface rash, it produces a hot, tender, spreading area of redness or darkening with swelling, and it often makes people feel unwell. Cellulitis always needs medical assessment and antibiotics — it does not settle on its own.
Medically reviewed by Dr. Celina Kazumi Iwasa, MD · Last reviewed 2026-08-23
Quick answer
Cellulitis is a deep bacterial skin infection that causes an expanding area of red, warm, swollen and painful skin, most commonly on the lower leg, often with fever and feeling unwell. It usually follows a break in the skin and is treated with oral antibiotics for 5–7 days, or intravenous antibiotics in hospital when it is severe or spreading fast. Seek same-day medical care if you suspect cellulitis.
What cellulitis looks like
Cellulitis shows four cardinal features together: redness or darkening, warmth, swelling and pain. The affected area has an indistinct, spreading edge — quite unlike the sharply bordered patches of eczema or psoriasis — and it is almost always on one side of the body only.
Common locations
- Lower leg and ankle (by far the most common site)
- Face and around the eye (periorbital — treat as urgent)
- Arms and hands, especially after a cut, bite or cannula
- Around surgical wounds or ulcers
- Skin folds and areas affected by lymphoedema
Typical signs
- Warm, tender, swollen skin with an ill-defined expanding border
- Shiny, tight or dimpled (orange-peel) skin surface
- Fever, chills, shivering and generally feeling unwell
- Blisters, small areas of bleeding into the skin, or weeping
- Tender swollen lymph nodes in the groin or armpit
On brown and Black skin
On brown and Black skin cellulitis may not look red at all — it can appear darker brown, purple or grey, and the diagnosis rests on warmth, swelling, tenderness and the area expanding over hours. Comparing with the opposite limb is the most useful check.
Causes and triggers
Cellulitis develops when bacteria — usually Streptococcus pyogenes or Staphylococcus aureus — enter through a break in the skin and multiply in the deeper tissue. Often the entry point is small and easily overlooked.
| Trigger | Why it matters |
|---|---|
| Cuts, grazes and bites | Any wound, insect bite, animal bite or injection site can act as the entry point. |
| Athlete's foot and cracked heels | Fungal infection between the toes is a very common and treatable cause of recurrent leg cellulitis. |
| Leg ulcers and eczema | Chronic broken or weeping skin gives bacteria continuous access. |
| Lymphoedema and venous disease | Poor lymphatic drainage and chronic swelling both raise the risk substantially and make recurrence likely. |
| Diabetes | Reduced sensation, poor healing and impaired immunity increase both risk and severity, particularly on the feet. |
| Immunosuppression | Chemotherapy, long-term steroids or immune-modulating drugs allow infection to establish and spread faster. |
Conditions that look similar
Around a third of suspected cellulitis turns out to be something else. The strongest clue against cellulitis is redness on both legs at once — true cellulitis is nearly always one-sided.
| Condition | How to tell it apart |
|---|---|
| Venous eczema / stasis dermatitis | Both lower legs, itchy rather than painful, dry and scaly with brown staining, no fever. |
| Deep vein thrombosis | Swelling and calf pain with less warmth and no clear skin change — needs urgent assessment in its own right. |
| Contact dermatitis | Itchy rather than tender, sharply matched to what touched the skin, no fever or malaise. |
| Lipodermatosclerosis | Chronic firm, tight, inverted champagne-bottle lower leg in venous disease, developing over months not hours. |
| Necrotising fasciitis | Pain far out of proportion to the skin appearance, rapid deterioration, dusky or blistered skin — a surgical emergency. |
Treatment options
Cellulitis is treated with antibiotics, elevation and treatment of the entry point. Improvement is expected within 48–72 hours; the redness may spread slightly in the first day even while treatment is working.
Antibiotics
Most cases are treated with 5–7 days of oral antibiotics such as flucloxacillin, with alternatives for penicillin allergy. Severe, rapidly spreading or facial cellulitis, or infection with fever and confusion, needs intravenous antibiotics in hospital.
Elevation and rest
Raising the affected limb above heart level whenever possible reduces swelling and speeds recovery. This is one of the most under-used and most effective parts of treatment.
Mark the edge
Draw around the border of the redness with a pen and note the time. If the area extends well beyond the mark or you feel worse, seek review the same day.
Treat the entry point
Treat athlete's foot, dress ulcers and moisturise cracked skin. Skipping this step is the main reason cellulitis recurs.
Prevent recurrence
For repeated episodes, compression therapy for chronic swelling, careful foot care and — in selected cases — long-term preventive antibiotics prescribed by a specialist can reduce the recurrence rate.
When to see a doctor
Suspected cellulitis always warrants same-day medical assessment. Some features mean emergency care rather than a routine appointment.
Red flags
- Rapidly spreading redness, or redness advancing within hours
- Severe pain out of proportion to how the skin looks, or dusky, purple or blistered skin
- High fever, chills, confusion, fast breathing or feeling very unwell
- Cellulitis on the face or around the eye
- Any cellulitis in someone with diabetes, immunosuppression, or a prosthetic joint or implant
Frequently asked questions
What are the first signs of cellulitis?
The first signs are a small area of skin that becomes warm, tender and red or darker than the surrounding skin, with swelling that spreads outward over hours. Many people also feel shivery, tired or feverish before the skin change is obvious. Cellulitis is nearly always on one side of the body only.
How fast does cellulitis spread?
Cellulitis can extend noticeably within hours. Marking the border with a pen and writing the time lets you and your clinician judge progress. Rapid expansion, severe pain or feeling very unwell means emergency assessment rather than waiting for a routine appointment.
Can cellulitis heal without antibiotics?
No. Cellulitis is a deep bacterial infection and needs antibiotics. Untreated, it can spread into the bloodstream and cause sepsis. Elevation and rest help recovery but do not replace antibiotic treatment.
How long does cellulitis take to clear up?
With appropriate antibiotics most people begin to improve within 48–72 hours and complete a 5–7 day course. Swelling, discolouration and skin flaking can take several weeks to settle fully, which is normal and not a sign that the infection persists.
Is cellulitis contagious?
No. Cellulitis affects tissue beneath the skin surface and is not passed from person to person by touch. The bacteria that cause it are common on skin generally; the infection depends on them entering through a break in your own skin.
Why does my cellulitis keep coming back?
Recurrence is usually driven by an untreated entry point or persistent swelling — most often athlete's foot between the toes, a leg ulcer, dry cracked skin, or lymphoedema. Treating the fungal infection, using emollients and wearing prescribed compression substantially reduce repeat episodes.
Not sure if it is cellulitis?
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Check your skin nowRelated guides
- Cellulitis: full clinical A–Z entry
- Impetigo
- Folliculitis
- Eczema (atopic dermatitis)
- Skin rash types: identify a rash by pattern
This page is for general information and does not replace a medical consultation. If you are worried about a skin change, see a qualified clinician.