What is cellulitis?

Cellulitis is a bacterial infection of the skin, which can become serious if not treated quickly with antibiotics.

Cellulitis often affects the lower leg, but can occur on any part of the body including the face.

If you think you or someone in your care has cellulitis, it's important to get medical attention as soon as possible.

It is particularly important to get urgent medical help if:

• the affected skin is on the face
• there is an animal or human bite
• the redness is spreading very quickly or is very painful
• you have a fever
• you have a chronic disease such as diabetes or weak immune system

Sometimes bacteria from cellulitis can spread into the blood stream, which is called septicaemia. This can trigger sepsis, which is a medical emergency.

People with cellulitis can quickly become very unwell and a small number of people may develop serious complications.

What are the symptoms of cellulitis?

People with cellulitis have an area of skin that is:

• red and inflamed
• very painful
• tender
• swollen or tight
• warmer to touch than surrounding skin
• redness and inflammation that is expanding in area

People with cellulitis symptoms may also have:

• fever
• chills, shaking or sweating
• nausea
• feeling generally unwell
• blisters or ulcers
• red spots
• skin dimpling
• weeping of clear, yellow or pus like fluid
• enlarged glands (lymph nodes)

What causes cellulitis?

Cellulitis is usually caused by a bacterial infection. Group A streptococcus and Staphylococcus aureus (staph) are the most common bacteria involved. These bacteria normally live on a person’s skin without causing any harm, but if skin is broken they can infect the tissue and cause cellulitis.

The infection usually occurs when bacteria enter the skin through an ulcer, cut, scratch or insect bite. It can also happen when there is already a skin problem like eczema, psoriasis, scabies or acne, or after surgery. However, it can occur without any visible damage to the skin.

A common cause of cellulitis is scratching the skin with fingernails that carry bacteria.

Some people are more likely than others to get cellulitis. People are more likely to get cellulitis if they have a skin condition that makes them itchy and are more likely to scratch.

People are also more likely to get cellulitis if they:

• have swelling in an arm or leg such as with lymphoedema
• have poor circulation or have a weak immune system
• have diabetes

How is cellulitis diagnosed?

A doctor will diagnose cellulitis simply by talking to you, then looking at and touching the affected area.

Sometimes blood samples will be taken to look for the type of bacteria involved, and sometimes swabs of the skin or wound to rule out other conditions. They might order an ultrasound.

The most important thing is to treat the cellulitis early so that the condition does not get worse. This can quickly become an emergency if left too long.

How is cellulitis treated?

Cellulitis is usually treated with:

• antibiotics
• rest
• elevating or raising the affected part
• compression, especially if lower limb

While cellulitis is not generally contagious, it's important to always wash your hands before and after touching the infected area. This will reduce the chance of spreading the infection further.

You may need painkillers. Some doctors may advise you to take anti-inflammatory medicines, and some may advise you to take steroids for a short time.

Your doctor or nurse might draw on your skin to outline the area of the cellulitis. This can tell you whether the area affected is getting bigger or smaller.

Sometimes the type of antibiotic may need to be changed, and in more severe cases antibiotics may need to be given intravenously in hospital. Make sure you take the antibiotic exactly as prescribed by your doctor.

When you’re at home, try placing a cool, damp cloth on the affected area as often as you need to reduce the discomfort. Keep the affected limb raised and talk to your doctor about whether you need compression stockings. Do not touch or rub the infected area.

Can cellulitis be prevented?

Cellulitis cannot always be prevented, but the risk of developing cellulitis can be reduced by:

• avoiding injury to the skin
• maintaining good hygiene
• managing skin conditions like tinea and eczema.

People who are susceptible to cellulitis — such as those with diabetes or with poor circulation — should take care to protect themselves with appropriate footwear, gloves and long pants when gardening or bushwalking. Look after your skin by moisturising regularly and checking your feet for signs of injury.

A common cause of infection to the skin is via the fingernails. Handwashing is very important, as well as regularly trimming and cleaning your nails.

If your skin is cut:

• rinse the wound with clean water
• use tweezers to pick out any dirt or debris
• cover the wound with a non-stick dressing
• see a doctor or nurse if the wound is deep

Make sure you wash your hands before cleaning or dressing any wounds.

People with swelling of the arm or leg due to a condition such as lymphoedema sometimes develop cellulitis that keeps coming back. In these cases, the first step is to work with your doctor to find the cause of the swelling and prevent the cellulitis happening. In people who have cellulitis 2 or more times in a year, taking antibiotics for long periods can help.