Cellulitis

What is cellulitis?

Cellulitis is a bacterial infection of the deeper layers of the skin and the tissues underneath it.

It can occur anywhere on the body but is particularly common in the feet and lower legs.

Bacteria normally live harmlessly on the surface of our skin. Cellulitis can develop when bacteria enter through a break in the skin — sometimes through something so small that you may not have noticed it.

Cellulitis is not usually passed from one person to another, because the infection occurs within the deeper layers of the skin rather than on its surface.

What causes cellulitis?

Cellulitis may develop following:

  • A cut, graze or puncture wound

  • Cracked or very dry skin

  • A blister

  • An insect bite

  • A surgical wound

  • A foot ulcer or other open wound

  • Cracks between the toes caused by athlete's foot (tinea pedis)

  • Trauma around a toenail

  • Other damage that allows bacteria through the normal protective barrier of the skin

Sometimes no obvious break in the skin can be found.

What are the symptoms?

An area affected by cellulitis typically becomes:

  • Painful or tender

  • Hot

  • Swollen

  • Red or darker than the surrounding skin

  • Increasingly inflamed

  • Tight or uncomfortable

The affected area may gradually increase in size.

On brown or black skin, redness may be much less obvious. Changes in temperature, swelling, tenderness and skin colour compared with the surrounding area may therefore be more noticeable.

Some people also develop:

  • Fever or a high temperature

  • Chills or shivering

  • Feeling generally unwell

  • Swollen glands

Who is more at risk?

Anyone can develop cellulitis, but the risk is increased if you:

  • Have previously had cellulitis

  • Have lymphoedema or persistent swelling

  • Have diabetes

  • Have reduced circulation

  • Have reduced mobility

  • Have a weakened immune system

  • Have wounds or ulcers

  • Have recently had surgery

  • Have damaged, cracked or very dry skin

  • Have athlete's foot or other breaks between the toes

People with lymphoedema are particularly susceptible because fluid collecting within the tissues increases the risk of infection.

Is cellulitis serious?

It can be.

Most cases respond well when treatment is started promptly. However, untreated cellulitis can spread to deeper tissues or into the bloodstream and cause serious illness.

For this reason, suspected cellulitis should not be watched for several days to “see how it goes”.

If you think you have cellulitis

Contact your GP urgently or NHS 111 for assessment.

Cellulitis is normally treated with antibiotics. NICE recommends antibiotic treatment when cellulitis or erysipelas is diagnosed.

How is cellulitis treated?

Most uncomplicated cases can be treated with oral antibiotics.

More severe infections, or infections in someone who is particularly unwell, may require hospital assessment and antibiotics given intravenously.

Once treatment has started, symptoms should begin to improve within approximately 2–3 days, although the skin can take longer to return completely to normal. Seek further medical advice if the infection is rapidly worsening at any stage or has not started to improve within this period.

Always complete your prescribed course of antibiotics unless the healthcare professional treating you advises otherwise.

Looking after yourself while recovering

While you are recovering:

  • Rest when required, but continue gentle movement

  • Elevate the affected leg or foot when sitting or lying down to help reduce swelling

  • Regularly move the ankle and nearby joints to prevent stiffness

  • Drink plenty of fluids

  • Take pain relief where appropriate for you

  • Take antibiotics exactly as prescribed

  • Avoid scratching or damaging the affected skin

NHS advice is not to wear compression stockings during an acute episode of cellulitis until you are better, unless the healthcare professional responsible for your care has specifically advised otherwise.

Can I draw around the redness?

Yes.

Where there is a clearly visible edge to the affected area, marking around it can help monitor whether the inflammation is spreading.

NICE recommends that clinicians consider marking the extent of cellulitis when treatment begins for this reason.

A small amount of change immediately after starting treatment does not necessarily mean that antibiotics have failed, but rapid or significant spreading should be reassessed.

When to seek emergency help

Call 999 or attend A&E immediately if someone with cellulitis develops:

  • A very high temperature or severe shivering

  • Very fast breathing

  • A racing heartbeat

  • Dizziness or fainting

  • Confusion or disorientation

  • Cold, pale or clammy skin

  • Purple patches developing on the skin

  • Becoming difficult to wake or unresponsive

These may indicate a serious complication such as sepsis and require emergency treatment.

Is every red, hot leg cellulitis?

No.

A number of conditions can resemble cellulitis, including:

  • Chronic venous insufficiency

  • Venous eczema

  • Lipodermatosclerosis

  • Superficial thrombophlebitis

  • Deep vein thrombosis (DVT)

  • Gout

  • Inflammatory reactions following bites or injuries

NICE specifically recommends considering other causes of skin redness, including chronic venous insufficiency, before diagnosing cellulitis.

Cellulitis commonly affects one limb rather than both simultaneously. Redness and swelling affecting both lower legs therefore deserves careful assessment rather than automatically being assumed to be infection.

Can cellulitis come back?

Unfortunately, yes.

Having cellulitis previously increases the chance of another episode. Certain underlying conditions — particularly persistent oedema, lymphoedema, venous disease and recurrent breaks in the skin — can also increase the risk.

Reducing your risk

Good foot and skin care can make a real difference.

Try to:

  • Keep the skin clean and well moisturised

  • Treat cracked skin promptly

  • Check your feet regularly for cuts, grazes, blisters and wounds

  • Treat athlete's foot promptly

  • Dry carefully between the toes after washing

  • Wear well-fitting footwear to reduce rubbing and blistering

  • Avoid walking barefoot where injury is likely

  • Manage swelling or lymphoedema according to the advice of your healthcare team

  • Seek help for wounds that are not healing normally

The NHS particularly recommends prompt treatment of athlete's foot in people at increased risk of cellulitis.

Cellulitis and your podiatry care

At Blackfords Footcare, we may identify changes during examination of the feet and lower limbs that are suspicious for cellulitis.

We can also help identify and manage some of the foot-related factors that may increase the risk of future infection, including fungal infections, fissured skin, pressure damage and wounds.

However, suspected acute cellulitis requires medical assessment and antibiotic treatment and is not treated as a routine podiatry condition.

If we are concerned that you may have cellulitis, we will advise you to seek appropriate medical assessment rather than continuing with routine treatment.

If you have a rapidly developing hot, swollen, painful or discoloured foot or leg, please do not wait for your next podiatry appointment. Contact your GP or NHS 111 urgently.