Introduction

Cellulitis is an infection of the deeper layers of the skin and the underlying tissue.

The main symptom of cellulitis is the affected area of skin suddenly turning red, painful swollen and hot.

It most often affects the legs, but can occur anywhere on the body.

When to see your GP

See your GP immediately if an area of skin suddenly turns red, hot and tender. If you can't see your GP on the same day, visit a walk-in centre or minor injuries unit.

Find a local walk-in centre or minor injuries unit using our service search.

Your GP can usually diagnose cellulitis by assessing your symptoms and examining your skin.

In some cases, further tests may be needed to rule out similar conditions, such as varicose eczema, or to assess the severity of the infection.

Hospital treatment

Certain symptoms can indicate that the infection has spread from your skin to other parts of the body, such as the blood. These include:

  • vomiting
  • fever
  • rapid breathing
  • confusion or disorientation

If you experience these severe symptoms, go to your local accident and emergency (A&E) department or call 999 for an ambulance.

Causes of cellulitis

Cellulitis can have a wide range of causes, but the majority of cases are caused by group A streptococcal infections or staphylococcal infections. In rarer cases, it may be caused by a fungal infection.

Cellulitis develops when bacteria or fungi move down through the skin’s surface through a damaged or broken area of skin, such as a cut, burn or bite.

Having a skin condition such as eczema or a fungal infection of the foot or toenails (athlete’s foot) can cause small breaks and cracks to develop in the surface of the skin. This makes a person more vulnerable to cellulitis.

Read about the causes of cellulitis, including more information on who is at risk.

Treating cellulitis

Cellulitis usually responds well to treatment with antibiotics if it's diagnosed and treated promptly.

As a precaution, hospital admission is usually recommended for more severe cases of cellulitis that fail to respond to antibiotic tablets. Once you have recovered you can usually be treated with antibiotics at home or as an outpatient.

Read more about treatment for cellulitis.

Complications

In some cases of cellulitis the bacteria triggers a secondary infection somewhere else in the body, such as in the blood (septicaemia).

Blood poisoning can be life-threatening and often requires hospital admission for treatment with intravenous antibiotics (antibiotics given directly into a vein).

Other complications can include:

  • abscesses
  • necrotising fasciitis – a rare bacterial infection of the deep layer of skin that causes the affected tissue to die
  • facial cellulitis – which can lead to meningitis if untreated

Read more about complications of cellulitis.

Who is affected?

Cellulitis can affect people of all ages, including children. Rates are thought to be roughly similar in both sexes.

In 2012, around 50,000 people were admitted to hospital in England as a result of cellulitis.

Symptoms

Cellulitis causes the area of affected skin to become red, hot, swollen, and tender or painful.

Cellulitis most commonly affects one of your legs, although symptoms can develop in any area of your body.

If you have cellulitis, you may also find that blisters develop on your skin.

Cellulitis can make you feel generally unwell, causing symptoms that develop before, or in combination with, changes to your skin. These symptoms include:

  • nausea
  • shivering
  • chills
  • a general sense of feeling unwell

When to seek medical advice

See your GP as soon as possible if an area of your skin suddenly turns red, painful and hot.

If it's not possible to see your GP on the day your symptoms develop, visit your local minor injuries unit.

When to seek urgent medical advice

Additional symptoms can suggest the infection has begun to spread from your skin to other parts of your body, such as your blood.

If you have any of these symptoms, go to your nearest accident and emergency (A&E) department as soon as possible, because you may need urgent medical attention.

These symptoms include:

  • rapid spreading of the area of redness
  • high temperature (fever) of 38C (100.4F) or above
  • vomiting
  • changes in mental state, such as confusion
  • rapid heartbeat
  • rapid breathing
  • dizziness, particularly when moving from a lying or sitting position to a standing one

Causes

Cellulitis is usually caused by an infection of the tissues beneath the skin after the surface of the skin is damaged.

The type of infection is usually either:

  • a group A streptococcal infection
  • a staphyloccocal infection

If the surface of your skin is damaged, this creates an entry point for bacteria, allowing them to attack the skin and tissue underneath. The break may be so small it's not noticeable.

A break in the skin may be caused by a:

Some cases of cellulitis can develop if a wound or other break in the skin is exposed to water that is contaminated with bacteria.

A fungal infection is a much rarer cause of cellulitis. Fungal cellulitis usually only affects people with a severely weakened immune system, such as a person in the final stages of an HIV infection that is not responding to treatment.

Who is at risk?

A number of health conditions can increase your risk of developing cellulitis. These include:

  • being obese (excessively overweight)
  • having a weakened immune system
  • having poorly controlled diabetes
  • having circulation problems
  • having chickenpox or shingles
  • having lymphoedema
  • having long-term untreated athlete's foot or fungal toenail infection
  • intravenous drug use
  • having previous episodes of cellulitis

These are briefly discussed below.

Obesity

Being obese can cause swelling in your legs, which may increase your risk of developing cellulitis.

Obesity is defined as being very overweight with a body mass index (BMI) of 30 or more. 

Weakened immune system 

Your immune system may be weakened if you have a condition such as HIV and AIDS. Having a weakened immune system makes it harder for your body to fight off infection.

A number of treatments are also known to weaken the immune system. For example:

  • chemotherapy – a cancer treatment that uses medication to kill cancerous cells
  • immunosuppressants (medications that are widely used to treat people who have had organ transplants to prevent their body rejecting the donated organ)
  • long-term use of corticosteroids tablets and corticosteroid creams

Poorly controlled diabetes

If you have diabetes that is not adequately treated or controlled, it can weaken your immune system.

Poorly controlled diabetes can also affect your circulation, which can sometimes cause skin ulcers to develop. Skin ulcers are a common entry point for bacteria.

Circulation problems

Poor circulation can increase your risk of developing skin infections in the places where your body does not have an adequate blood supply.

For example, many people with diabetes have a reduced blood supply to their feet, which makes them more vulnerable to developing cellulitis.

Chickenpox and shingles

Chickenpox and shingles often cause blisters to develop on your skin. Chickenpox (which usually only affects children) and shingles (which usually affects people aged 50 and older) are viral infections caused by the herpes varicella-zoster virus.

If the blisters that occur in chickenpox or shingles are broken or scratched, it can damage your skin and provide an entry point for bacteria.

Lymphoedema

Lymphoedema is a condition that causes fluid to build up under your skin. It may occur following surgery for some cancers. If your skin becomes very swollen it may crack, creating an entry point for bacteria.

Intravenous drug use

People who inject illegal drugs have an increased risk of developing cellulitis, because poor needle hygiene, such as not sterilising the needle before and after injections, can increase the risk of infection. 

Previous episodes of cellulitis 

If you have had a previous episode of cellulitis, your risk of having episodes in the future increases.

An estimated 20-30% of people with a previous history of cellulitis will be admitted to hospital again with another cellulitis infection. The average time between a previous and recurring cellulitis infection is 3 years.

Treatment

Treatment for cellulitis depends on what caused the infection, the severity of your symptoms and the general state of your health.

You can usually be treated at home with antibiotics if you have mild symptoms.

Hospital treatment may be necessary if you have symptoms such as fever, nausea and vomiting which suggest the infection has spread from your skin to your bloodstream or other parts of the body.

Treatment at home

Antibiotics

If you are well enough to be treated at home, you will be given a course of antibiotic tablets.

The length of the course will depend on your circumstances, including how quickly you respond to treatment and whether you have any underlying conditions such as lymphoedema.

The most commonly prescribed antibiotic for cellulitis is flucloxacillin, which is part of the penicillin group of antibiotics.

The most common side effects of flucloxacillin are mild digestive problems, such as an upset stomach or episodes of diarrhoea.

If you cannot take flucloxacillin because you're allergic to penicillin, alternative antibiotics such as erythromycin or clarithromycin can be used.

If it's suspected that your cellulitis was caused by a wound being exposed to contaminated water, you will be given a combination of 2 different antibiotics. This is usually doxycycline or ciprofloxacin in combination with flucloxacillin or erythromycin.

When you first start taking the antibiotics, you may notice that your skin becomes redder. This is usually only a temporary reaction, and the redness should start to fade within 48 hours.

Contact your GP immediately if your symptoms get worse 48 hours after taking the antibiotics, or you develop additional symptoms, such as a high temperature or vomiting.

Self-care

There are steps you can take at home to ease your symptoms and speed your recovery from cellulitis.

Drink plenty of fluids to avoid dehydration.

If your leg is affected by cellulitis, keep it raised whilst you are resting, using pillows or a chair. This should make you feel more comfortable and help to reduce the swelling. If possible, the foot should be raised higher than the hip. If your arm is affected, try and keep your lower arm raised above your elbow.

If it's uncomfortable to raise the limb, try to lie down as much as possible. However, it's important to still regularly move the joints, such as your wrists or ankles.

Try to avoid cuts and grazes from activities that increase the risk. For example, by wearing clothing that covers your arms or legs when gardening.

You can also take steps to help prevent cellulitis from reoccurring. For example:

  • maintaining good hand hygiene
  • keeping your skin moisturised
  • treating cuts and grazes or any broken skin caused by a condition such as eczema
  • treating fungal infections of the hands or feet, such as athlete's foot
  • long-term antibiotics may be prescribed if you experience recurrent cellulitis (more than 2 episodes a year in the same area)
  • treatments for lymphoedema if you are diagnosed with the condition

Read more information about preventing cellulitis.

Pain relief

If your cellulitis is causing pain or a high temperature (fever), an over the counter painkiller such as paracetamol or ibuprofen may help.

Treatment at hospital

If you need to be admitted to hospital for treatment, you will be given antibiotics directly into your vein through an injection or a drip (known as intravenous antibiotics).

Once you have recovered from the initial symptoms you can usually be treated with antibiotics at home or as an outpatient, rather than staying in hospital.

The type of antibiotics used depends on the suspected cause of your infection, although a type of antibiotic known as a broad-spectrum antibiotic is often used. This type of antibiotic can kill a range of different strains of bacteria.

Complications

Complications of cellulitis can include blood poisoning, abscesses, necrotising fasciitis and meningitis.

Blood poisoning (septicaemia)

If the bacteria infecting your skin and tissue enter your bloodstream, it can lead to blood poisoning (septicaemia). Symptoms of blood poisoning include:

  • high temperature (fever) of 38C (100.4F) or above
  • rapid heartbeat
  • rapid breathing
  • feeling dizzy or faint
  • changes in mental behaviour, such as confusion or disorientation
  • diarrhoea
  • reduced urine flow
  • cold, clammy skin
  • pale skin
  • loss of consciousness

If you have any of these symptoms, call 999 for an ambulance.

Read more information about blood poisoning.

Abscess

Some cases of cellulitis can result in an abscess forming near the site of the infection.

An abscess is a swollen, pus-filled lump under the surface of the skin. It is caused by a build up of bacteria and dead white blood cells.

In some cases, the antibiotics used to treat cellulitis may also help to remove the abscess. But if not, the pus will have to be drained from the abscess through a small cut in your skin.

Necrotising fasciitis

Necrotising fasciitis is a rare but serious bacterial infection of the deep layer of skin. This causes the affected tissue to die (gangrene).

Symptoms develop rapidly and include very severe pain, fever, diarrhoea, vomiting and unconsciousness.

Treatment includes surgery to remove the affected tissue and antibiotics.

There are around 500 cases of necrotising fasciitis in the UK every year.

Facial cellulitis and meningitis

Facial cellulitis is an uncommon form of cellulitis that develops on the skin of the face. It accounts for an estimated 8.5% of all cases of cellulitis.

Facial cellulitis is most common in children under 3 years old and older adults above 50. If facial cellulitis is left untreated in children, the bacteria can potentially spread to the outer membranes of their brain (the meninges) and trigger a serious brain infection called meningitis.

Symptoms of meningitis can differ in adults, but symptoms in babies and children under 3 years old include:

  • becoming floppy and unresponsive, or stiff with jerky movements
  • becoming irritable and not wanting to be held
  • unusual crying
  • vomiting and refusing feeds
  • pale and blotchy skin
  • loss of appetite
  • staring expression
  • very sleepy and reluctant to wake up

Bacterial meningitis is serious and should be treated as a medical emergency. If left untreated, a bacterial infection can cause severe brain damage and infect the blood.

If you suspect your child has symptoms of meningitis, call 999 immediately for an ambulance.

The best way to protect your child against meningitis is to make sure they have been vaccinated with the:

The vaccine and the booster provide immunity against 2 leading causes of meningitis in children:

  • haemophilus influenzae type b bacteria
  • group C meningococcal bacteria

Ask your GP if you're unsure whether your child’s vaccinations are up to date.

Read about meningitis.

Prevention

Not all cases of cellulitis can be prevented. But you can take steps to reduce the risk of developing the condition.

These involve steps to prevent skin wounds, and treating wounds properly when they occur.

Treating skin wounds 

Make sure that any cuts, grazes or bites are kept clean. Wash the damaged skin under running tap water and, if necessary, apply an antiseptic cream.

Keep the wound covered with a plaster or dressing. Make sure you change the plaster or dressing if it becomes wet or dirty. Plasters and dressings will reduce the risk of the wound being damaged further, and they will help to create a barrier against bacteria entering the skin. 

Read more about how to clean a wound.

Hand hygiene

Wash your hands regularly, particularly when treating or touching a wound or skin condition.

If you have an itchy skin condition, such as atopic eczema or chickenpox, keep your fingernails clean and short at all times.

If you scratch your skin and your fingernails are short and clean, the risk of skin damage and infection will be reduced.

Keep your skin moisturised

If your skin is dry or prone to cracking, keep your skin well moisturised. Cracked skin can create an entry point for bacteria.

Preventing recurrent cellulitis

People who experience frequently recurring cellulitis, such as those with lymphoedema (a condition that causes swelling of the arms and legs), may be recommended to begin taking antibiotics on a long-term basis to protect against further infection.

If you are diagnosed with lymphoedema, you may be given a 2-week course of antibiotics to take in case you start having the initial symptoms of cellulitis.

If you have more than 2 episodes of cellulitis in a year, your GP may refer you to a dermatologist (skin specialist) to discuss the option of taking antibiotics on a long-term basis to protect against further infections.