Cellulitis: Symptoms, Urgent Signs and Treatment

Cellulitis is a bacterial infection in deeper skin tissues that causes painful, warm, swollen skin and requires timely antibiotic treatment.

It commonly affects a lower leg but can occur anywhere, including the face and around a wound. The infection is different from cellulite, the harmless dimpled appearance of skin. Prompt care matters because bacteria can extend through tissue or enter the bloodstream.

Most people with cellulitis notice painful or tender skin, and spreading redness is a very common presentation. The area may feel hot, look swollen and have poorly defined edges. On darker skin, redness may be subtle; warmth, tenderness, swelling and a change from the person's usual skin tone can be more apparent.

Fever, chills and feeling unwell can accompany the skin changes. Obtain urgent medical care for rapidly spreading discolouration, severe or escalating pain, confusion, faintness, fast breathing, marked drowsiness, purple or black skin, or swelling around an eye. These features can signal a serious infection and should not wait for a routine appointment.

Bacteria can pass through a break in the protective skin barrier. The entry point may be a cut, cracked skin, an ulcer, an injection site, recent surgery, an insect bite or a fungal rash between the toes. Sometimes the opening is too small to see.

Cellulitis itself is not generally passed through casual contact. Good hand hygiene and covering an open or draining wound still help prevent bacteria from spreading between people or to another part of the body.

The affected patch can enlarge as inflammation spreads through deeper skin. Appropriate antibiotics begin controlling the bacteria, although warmth and discolouration may take longer to settle than fever or pain. A clinician should reassess symptoms that continue to extend, become more painful or are accompanied by new systemic illness.

Some people experience repeat episodes, especially when leg swelling, broken skin or an untreated fungal infection remains. Managing these underlying problems can reduce opportunities for bacteria to enter.

Risk is increased by eczema, athlete's foot, chronic ulcers, recent wounds, lymphatic damage and persistent limb swelling. Diabetes can affect skin integrity and healing, while medicines or conditions that weaken immune defences may make infection harder to contain. Previous cellulitis can leave drainage pathways less effective and make recurrence more likely.

Diagnosis is usually based on the appearance and feel of the skin, how quickly the patch changed, and symptoms such as fever. The clinician checks for a wound, toe-web cracking, an abscess and swelling, then considers other causes of a red leg such as a blood clot, eczema or inflammation without infection.

Blood tests may be used when illness is severe or the diagnosis is uncertain. A sample of pus or wound fluid can help identify bacteria when drainage is present. Imaging may be needed if an abscess, deeper infection, foreign material or another diagnosis is suspected.

Antibiotics are the main treatment. The choice and route depend on the infection site, severity, allergy history, other health conditions and whether the person can take medicine by mouth. More severe illness, facial involvement or difficulty keeping tablets down may require hospital assessment and antibiotics through a vein.

An abscess may need drainage because antibiotics alone may not clear a closed pocket of pus. Elevating an affected limb can ease swelling, and suitable pain relief can improve comfort. Finish the prescribed course unless the treating clinician changes it, and do not use leftover antibiotics.

Rest, drink enough fluids and move nearby joints gently if comfortable. Take each antibiotic dose as directed. Marking the visible edge of redness can help show whether it is extending, but skin tone, pain, swelling and general wellbeing also need attention.

Keep wounds clean and covered as advised. Arrange reassessment if fever persists, the area expands, pain intensifies, new blisters appear or medicine causes a concerning reaction such as facial swelling or breathing trouble.

Infection may form an abscess, spread along lymph vessels, reach deeper structures or enter the bloodstream and cause sepsis. Tissue damage can occur in aggressive infections. Repeated episodes may worsen long-term limb swelling, which in turn makes another episode easier to develop.

Wash minor cuts, cover them with a clean dressing and watch for increasing pain, warmth or discharge. Moisturise dry skin to limit cracks, wear suitable footwear and treat athlete's foot. People with leg swelling can ask a clinician about skin care and swelling management once any acute infection has been addressed.

A primary-care or urgent-care clinician can assess most suspected cellulitis and start treatment. Emergency services are appropriate for severe warning signs. Recurrent infections may warrant input from dermatology, infectious diseases, diabetes care, wound care or a lymphoedema service, depending on the underlying problem.