What is cellulitis?

Cellulitis is a bacterial infection of the skin spreading to the tissues under your skin. It can become serious if it's not treated quickly with antibiotics.

Cellulitis can occur on any part of your body including your face. A common place to have cellulitis is your lower leg.

If you have cellulitis, you can quickly become very unwell. There's also a small chance of getting serious complications.

If you think you have cellulitis, it's important to see a doctor as soon as possible.

What are the symptoms of cellulitis?

If you have cellulitis, the affected area of skin may be:

• red and inflamed
• very painful
• tender
• swollen or tight
• warmer to touch than surrounding skin

You may have other symptoms including:

• fever, chills, shaking or sweating
• nausea
• blisters or ulcers weeping clear, yellow or pus-like fluid
• enlarged glands (lymph nodes) near the affected area of skin
• feeling generally unwell

What causes cellulitis?

Cellulitis is usually caused by a bacterial infection.

Group A streptococcus and staphylococcus aureus ('staph') are the most common causes of cellulitis. These bacteria normally live on your skin without causing any harm. But if your skin is broken they can infect your body and cause cellulitis.

A common cause of cellulitis is scratching your skin with dirty fingernails that carry bacteria. Cellulitis can also happen without any visible damage to your skin.

The infection usually happens when bacteria enter your skin through:

• an ulcer
• cut
• scratch
• insect bite
• a surgical procedure (operation)

Cellulitis can also happen if you already have a skin condition. This may make you itchy and more likely to scratch your skin. These conditions include:

• eczema
• psoriasis
• scabies
• acne

You're also more likely to get cellulitis if you:

• smoke
• live with obesity
• have diabetes
• have poor circulation or a weakened immune system
• have swelling in an arm or leg, such as lymphoedema

When should I see my doctor?

You should see your doctor if you are concerned that you have cellulitis.

It's important for a doctor to diagnose and treat cellulitis early so that your condition doesn't get worse. Cellulitis may become an emergency if left too long.

If you've already started antibiotics for cellulitis, you should see your doctor again if:

• the red area is getting bigger
• the area has red streaks
• there's a lot of pus
• you have new blisters

When to seek urgent care

It's important to get urgent medical help if:

• your face is affected
• you were bitten by an animal or human
• the redness is spreading quickly or is very painful
• you have a fever
• you have diabetes or a weakened immune system
• you are a smoker

How is cellulitis diagnosed?

Your doctor will ask about your symptoms and medical history. They will examine the affected part of your skin. They may send you for blood tests.

If there is discharge (pus) from your skin, they may take a swab to send for testing.

These tests can help your doctor find out which bacteria is causing your infection. Then they can see which antibiotic will be the most effective.

How is cellulitis treated?

Cellulitis is usually treated:

• with antibiotics
• with rest
• by elevating (raising) the affected part of your body, if possible
• by draining the source of infection

It's important to always wash your hands before and after touching the infected area.

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

Self-care at home

When you're at home, placing a cool, damp cloth on the affected area can help reduce any discomfort. Keep the affected limb raised and ask your doctor about whether you might benefit from compression stockings. Do not touch or rub the infected area.

Medicines for cellulitis

The main treatment for cellulitis is antibiotics. Your doctor will choose an antibiotic based on which bacteria is causing your infection. They will also think about where the cellulitis is and how bad it is.

Make sure you take the antibiotic exactly as your doctor tells you. If your cellulitis doesn't improve, you may need a different antibiotic.

In more severe cases you may need intravenous (IV) antibiotics in hospital.

As cellulitis can be painful, you may also need to take pain relief medicine such as paracetamol.

What are the complications of cellulitis?

If cellulitis is not treated, your swelling and pain can get worse.

Sometimes, bacteria from cellulitis can spread into your bloodstream. This is called septicaemia and can also lead to a serious whole-body infection called sepsis.

Symptoms of sepsis can include:

• fever or chills
• fast heart rate
• fast breathing
• confusion or difficulty staying awake
• looking unwell
• feeling dizzy

Another rare complication is necrotising fasciitis. This is a severe infection deep inside your body tissues or muscles.

These complications need to be urgently treated in hospital.

Can cellulitis be prevented

You can lower your chance of developing cellulitis by:

• maintaining good hygiene
• avoiding cuts, grazes and other injuries to your skin
• managing skin conditions like tinea and eczema
• maintaining a healthy weight, as obesity increases your risk of cellulitis

Some people are more likely to get cellulitis, for example, if you have diabetes or poor circulation.

If you are at high risk, take extra care to protect yourself. Wear 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 your skin is through your fingernails. It's important to wash your hands often and to trim and clean your nails regularly.

If your skin is cut or broken:

• Rinse your wound with clean water.
• Use tweezers to pick out any dirt or debris.
• Cover your wound with a non-stick dressing.
• See a doctor or nurse if your wound is deep.

Make sure you wash your hands before cleaning or dressing any wounds to avoid introducing bacteria into the wound.

If you have ongoing swelling of your arm or leg, you may develop cellulitis that keeps coming back. Ask your doctor about finding the cause of your swelling to help prevent this from happening.

If you have cellulitis 2 or more times in a year, taking antibiotics for long periods can help.

Resources and support

For more information on cellulitis, read this fact sheet from NSW Health. It's also available in languages other than English.

For information on cellulitis in children visit the Royal Children's Hospital Melbourne webpage.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.