What is Cellulitis? Causes, Symptoms and Treatment

Cellulitis is a serious but treatable bacterial skin infection that affects thousands of people every year. Despite how common it is, cellulitis — if left untreated — can lead to serious complications.

In this article we explain exactly what cellulitis is, what causes it, what it looks like, and what you can do about it.

What is cellulitis?

Cellulitis is an acute bacterial infection of the deeper layers of the skin — specifically the dermis (the deeper layer of skin below the epidermis) and subcutaneous tissue (the layer beneath the skin). The condition differs from superficial skin infections by reaching deeper into the tissue and requiring more aggressive treatment.

Cellulitis is not contagious from person to person. It develops when bacteria — typically streptococci or staphylococci — enter the skin through a break or crack in the skin barrier.

What does cellulitis look like?

Cellulitis typically presents with the following symptoms:

Redness and swelling: The affected area is typically red, warm and swollen. The redness often starts locally and spreads over time.
Pain and tenderness: The area feels painful or tender to the touch.
Skin changes: The skin may appear tight and shiny. In some cases, blisters or sores may develop on the surface.
Fever and chills: With a more widespread infection, fever, fatigue and general malaise may occur.

Cellulitis most commonly appears on the shin (lower leg), but can occur anywhere on the body — including the face, arms and feet.

Why does cellulitis happen?

Cellulitis develops when bacteria find their way beneath the skin. Even small breaks in the skin barrier can be enough:

Skin injuries as entry points

Cuts, scrapes, insect bites, surgical wounds and even small cracks or fissures in the skin can all serve as entry points for bacteria. This is why people with poor immune function or underlying skin conditions are at higher risk.

Chronic skin conditions

Eczema, dermatitis and other chronic skin conditions weaken the skin's natural barrier function and make it easier for bacteria to penetrate. People with foot ulcers (particularly diabetics) are also at significantly increased risk.

Lymphedema and diabetes

Lymphoedema — a condition causing fluid retention and swelling — can impair the lymphatic system's ability to fight infection. Uncontrolled diabetes weakens the immune system and significantly increases the risk of serious bacterial infections.

Who gets cellulitis?

Anyone can develop cellulitis, but certain groups are more vulnerable:

Children: Frequent skin injuries and active lifestyles make children more vulnerable to minor wounds that can become entry points for bacteria.
Adults with chronic skin conditions or diabetes: A weakened skin barrier and compromised immune system significantly increase the risk.
People with weakened immune systems: Individuals with HIV/AIDS, cancer or those on immunosuppressive treatment are particularly susceptible.
Older adults: As age increases, immune effectiveness decreases and the skin's barrier function declines.

What can you do about cellulitis?

Cellulitis always requires medical treatment. Early diagnosis and appropriate antibiotic treatment are essential to prevent complications:

💊 Antibiotic treatment

Oral antibiotics (tablets) are the standard treatment for mild to moderate cellulitis. In severe cases, intravenous antibiotics (via drip) may be necessary. Treatment typically lasts 5–14 days.

🛏️ Rest and elevation

Keep the affected area at rest and elevated above heart level to reduce swelling and relieve pain.

🩹 Good wound care

Keep the affected area clean and covered with a loose bandage as directed by your doctor. Avoid applying pressure or constriction around the infected area.

🌡️ Monitor symptoms

Monitor your temperature and report any worsening symptoms — such as rapid spread of redness, high fever or confusion — to your doctor immediately.

Medical classification: Cellulitis is classified as 1B70 in the WHO's International Classification of Diseases (ICD-11) under 'Bacterial cellulitis, erysipelas or lymphangitis'. It is a bacterial infection of the dermis and subcutaneous tissue presenting with erythema and swelling.

Frequently asked questions

Is cellulitis dangerous?

Untreated cellulitis can lead to serious complications including blood poisoning (sepsis), deeper tissue infections and in rare cases amputation. Early treatment is essential.

How do I prevent cellulitis?

Treat all skin injuries — even small ones — immediately. Keep skin moisturised to avoid cracks, use protective equipment where there is a risk of skin injuries, and manage diabetes carefully.

Can cellulitis come back?

Yes, some people experience recurrent cellulitis, especially if they have underlying risk factors such as lymphoedema or diabetes. Your doctor may recommend preventive antibiotics in such cases.

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Disclaimer: This article is for informational purposes only and does not replace professional medical advice. Always consult a dermatologist for personal guidance.