Introduction

Impetigo is a common and highly contagious skin infection that causes sores and blisters. It's not usually serious and often improves within a week of treatment or within a few weeks without treatment.

Impetigo is the most common skin infection in young children in the UK, but it can affect people of all ages.

This topic covers:

Symptoms

When to seek medical advice

Causes

Treatment

Preventing the spread of impetigo

Preventing recurrent impetigo

Complications

Symptoms of impetigo

There are two types of impetigo:

  • non-bullous impetigo – the most common type
  • bullous impetigo

The symptoms of both types are described below.

Non-bullous impetigo

The symptoms of non-bullous impetigo begin with the appearance of red sores – usually around the nose and mouth but other areas of the face and the limbs can also be affected.

The sores quickly burst leaving behind thick, golden crusts typically around 2cm across. The appearance of these crusts is sometimes likened to cornflakes stuck to the skin.

After the crusts dry, they leave a red mark that usually fades without scarring. The time it takes for the redness to disappear can vary between a few days and a few weeks.

The sores aren't painful, but they may be itchy. It's important not to touch or scratch the sores because this can spread the infection to other parts of the body, and to other people.

Other symptoms, such as a high temperature (fever) and swollen glands, are rare but can occur in more severe cases.

Bullous impetigo

The symptoms of bullous impetigo begin with the appearance of fluid-filled blisters (bullae) which usually occur on the central part of the body between the waist and neck, or on the arms and legs. The blisters are usually about 1-2cm across.

The blisters may quickly spread, before bursting after several days to leave a yellow crust that usually heals without leaving any scarring.

The blisters may be painful and the area of skin surrounding them may be itchy. As with non-bullous impetigo, it's important not to touch or scratch the affected areas of the skin.

Symptoms of fever and swollen glands are more common in cases of bullous impetigo.

When to seek medical advice

Speak to your GP if you think you or your child may have symptoms of impetigo.

Impetigo isn't usually serious, but it can sometimes have similar symptoms to more serious conditions such as cellulitis (an infection of the deeper layers of skin) so it's important to get a correct diagnosis.

Your GP can also prescribe treatment to help clear up the infection more quickly than if it was left untreated.

Causes of impetigo

Impetigo occurs when the skin becomes infected with bacteria, usually either Staphylococcus aureus or Streptococcus pyogenes.

The bacteria can infect the skin in two main ways:

  • through a break in otherwise healthy skin – such as a cutinsect bite or other injury – this is known as primary impetigo
  • through skin damaged by another underlying skin condition, such as head lice, scabies or eczema – this is known as secondary impetigo

The bacteria can be spread easily through close contact with someone who has the infection, such as through direct physical contact, or by sharing towels or flannels.

As the condition doesn't cause any symptoms until four to 10 days after initial exposure to the bacteria, it's often easily spread to others unintentionally.

Children and people with diabetes or a weakened immune system – either due to a condition such as HIV or a treatment such as chemotherapy – are most at risk of developing impetigo.

Treating impetigo

Impetigo usually gets better without treatment in around two to three weeks.

However, treatment is often recommended because it can reduce the length of the illness to around seven to 10 days and can lower the risk of the infection being spread to others.

The main treatments prescribed are antibiotic creams or antibiotic tablets. These usually have to be used for around a week.

Read about treating impetigo.

Preventing the spread of impetigo

During treatment, it's important to take precautions to minimise the risk of impetigo spreading to other people or to other areas of the body.

Most people are no longer contagious after 48 hours of treatment or once their sores have dried and healed. It's important to stay away from work, school, nursery or playgroup until this point.

The advice below can also help to prevent the spread of the infection:

  • don't share flannels, sheets or towels with anyone who has impetigo – wash them at a high temperature after use
  • wash the sores with soap and water and cover them loosely with a gauze bandage or clothing
  • avoid touching or scratching the sores, or letting others touch them – it may help to ensure your nails are kept clean and short
  • avoid contact with newborn babies, preparing food, playing contact sports, or going to the gym – until the risk of infection has passed
  • wash your hands frequently – particularly after touching infected skin
  • washable toys should also be washed – wipe non-washable soft toys thoroughly with a cloth that has been wrung out in detergent and warm water and allowed to dry completely

If you think that the infection has spread to someone else, make sure they're seen by a GP as soon as possible.

Preventing recurrent impetigo

To reduce the risk of impetigo returning, make sure any cuts, scratches or bites are kept clean. Ensure any condition that causes broken skin, such as eczema, is treated promptly.

If you develop impetigo frequently, your doctor may suggest taking a swab from around your nose to see if you carry staphylococcal bacteria. These bacteria can live in the noses of some people without causing problems, although they can lead to impetigo if they infect broken skin nearby.

If you're found to carry these bacteria, you may be prescribed an antiseptic nasal cream to apply several times a day for five to 10 days in an attempt to clear the bacteria and reduce the chances of impetigo recurring.

Complications of impetigo

Complications of impetigo are rare, but they can sometimes occur and can be serious. Tell your GP if you have impetigo and your symptoms change or get worse.

Some complications associated with impetigo include:

  • cellulitis – an infection of the deeper layers of the skin and underlying tissue
  • scarlet fever – a rare bacterial infection that causes a fine, pink rash across the body
  • guttate psoriasis – a non-infectious skin condition that can develop in children and teenagers after a bacterial infection
  • septicaemia (a type of sepsis) – a bacterial infection of the blood
  • Staphylococcal scalded skin syndrome (SSSS) – a serious skin condition that looks like the skin has been scalded with boiling water
  • post-streptococcal glomerulonephritis – an infection of the small blood vessels in the kidneys

In very rare cases, impetigo may lead to some scarring, particularly if you scratch at the blisters, crusts or sores.

Symptoms

Impetigo does not cause any symptoms until four to 10 days after you first become infected. This means that people can easily pass the infection on to others without realising it.

There are two main types of impetigo, known as non-bullous and bullous impetigo, which have different symptoms. Most people with impetigo have the non-bullous type.

The symptoms of non-bullous and bullous impetigo are described below.

Non-bullous impetigo

The symptoms of non-bullous impetigo begin with the appearance of red sores – usually around the nose and mouth but other areas of the face and the limbs can also be affected.

The sores quickly burst leaving behind thick, golden crusts typically around 2cm across. The appearance of these crusts is sometimes likened to cornflakes stuck to the skin.

After the crusts dry, they leave a red mark that usually heals without scarring. The time it takes for the redness to disappear can vary between a few days and a few weeks.

The sores are not painful, but they may be itchy. It is important not to touch, or scratch, the sores because this can spread the infection to other parts of your body, and to other people.

Other symptoms, such as a high temperature (fever) and swollen glands, are rare but can occur in more severe cases.

Bullous impetigo

The symptoms of bullous impetigo begin with the appearance of fluid-filled blisters (bullae) which usually occur on the trunk (the central part of the body between the waist and neck) or on the arms and legs. The blisters are usually about 1-2cm across.

The blisters may quickly spread, before bursting after several days to leave a yellow crust that usually heals without leaving any scarring.

The blisters may be painful and the area of skin surrounding them may be itchy. As with non-bullous impetigo, it is important that you do not touch or scratch the affected areas of the skin.

Symptoms of fever and swollen glands are more common in cases of bullous impetigo.

When to seek medical advice

Most cases of impetigo will heal within two or three weeks without treatment, but you should still see your GP if you think you or your child may have the condition.

This is because the symptoms can be similar to more serious skin conditions and treatment can resolve the condition more quickly, as well as reduce the chances of the infection being spread to others.

Your GP will normally be able to diagnose impetigo by carrying out a simple examination of your skin.

Causes

Impetigo occurs when the skin becomes infected with bacteria, usually either Staphylococcus aureus or Streptococcus pyogenes.

These bacteria can infect the skin in two ways:

  • through a break in otherwise healthy skin, such as a cut, insect bite or other injury – this is known as primary impetigo
  • through skin damaged by another underlying skin condition, such as head lice, scabies or eczema – this is known as secondary impetigo

The bacteria can be spread easily through close contact with someone who has the infection, such as through direct physical contact, or by sharing towels or flannels.

As the condition does not cause any symptoms until four to 10 days after initial exposure to the bacteria, it is often easily spread to others unintentionally.

Impetigo stops being infectious after 48 hours of treatment starting or after the sores have stopped blistering or crusting.

Increased risk

In addition to the situations mentioned above, there are a number of other factors that can increase your chances of developing impetigo. These include:

  • being a child – impetigo is thought to be more common in children because their immune system has not yet fully developed and because they tend to spend time in places where the infection can easily be spread, such as schools and nurseries
  • having diabetes
  • being a carrier of Staphylococcus aureus bacteria – these bacteria can live in the noses of some people without causing problems, but they can sometimes cause impetigo if they get into damaged skin nearby
  • warm and humid weather – impetigo tends to be more common during the summer months in the UK, possibly because the warm and moist weather is a better environment for the bacteria to grow and/or because the skin is more likely to be exposed to insect bites and cuts at this time of year
  • having a weakened immune system, either due to a condition such as HIV or a treatment such as chemotherapy

Treatment

Impetigo isn't usually serious and often clears up without treatment after two to three weeks.

Treatment is often recommended as it can help clear up the infection in around seven to 10 days and reduce the risk of the infection being passed on to others.

If impetigo is confirmed, it can usually be effectively treated with antibiotics.

If the infection is being caused by an underlying skin condition, such as eczema, this may also need to be treated.

Antibiotic cream

For mild cases of impetigo that cover a small area, antibiotic cream is often recommended. This usually needs to be applied three or four times a day for seven days.

Before applying the cream, wash any affected areas of skin with warm, soapy water and try to clean off any crusts that have developed.

To reduce the risk of spreading the infection, it's also important that you wash your hands immediately after applying the cream or, if available, wear latex gloves while applying the cream.

Side effects of antibiotic cream can include:

  • irritation
  • redness
  • itchiness in the area where the cream is applied

If symptoms haven't improved after seven days of starting treatment, speak to your GP about other possible treatment options.

Antibiotic tablets

Antibiotic tablets may be prescribed if the infection is more severe and widespread, or if the symptoms don't improve after using antibiotic cream. These usually need to be taken two to four times a day for seven days.

If a course of oral antibiotics is prescribed for you or your child, it's very important that the course is finished even if the symptoms clear up before you've taken all the tablets. 

Common side effects of oral antibiotics include:

Speak to your GP if your symptoms haven't improved after seven days of treatment with antibiotic tablets.

Further testing and treatment

Further tests are usually only required in cases where the infection is severe or widespread, doesn't respond to treatment, or keeps recurring.

In these circumstances, your GP may refer you to a dermatologist (skin specialist) for further tests or they may take a swab of the affected skin themselves for testing.

This can help to rule out or confirm other skin conditions that may be responsible for your symptoms and can detect whether you carry one of the types of bacteria responsible for the infection inside your nose.

If your doctor thinks you may keep getting impetigo because you naturally have these bacteria inside your nose, they may prescribe you an antiseptic nasal cream to try to clear the bacteria.

Complications

Complications of impetigo are rare, but they can sometimes occur and can be serious. Tell your GP if you have impetigo and your symptoms change or get worse.

Some complications associated with impetigo are described below.

Cellulitis

Cellulitis occurs when the infection spreads to a deeper layer of skin. It can cause symptoms of red, inflamed skin with fever and pain. It can usually be treated with antibiotics, and painkillers can be used to relieve pain.

Guttate psoriasis

Guttate psoriasis is a non-infectious skin condition that can develop in children and teenagers after a bacterial infection. It is usually more common after a throat infection, but some cases have been linked to impetigo.

Guttate psoriasis causes small, red, droplet-shaped, scaly patches on the chest, arms, legs and scalp.

Creams can be used to control the symptoms and in some cases the condition will disappear completely after a few weeks.

Scarlet fever

Scarlet fever is a rare bacterial infection that causes a fine, pink rash across the body. Associated symptoms of infection, such as nausea, pain and vomiting, are also common. The condition is usually treated with antibiotics.

Scarlet fever is not usually serious but it is contagious. Therefore, it's important to isolate an infected child and avoid close physical contact. Keep your child away from school and other people until they have been taking antibiotics for at least 24 hours.

Septicaemia

Septicaemia (a type of sepsis) is a bacterial infection of the blood. It can cause:

  • diarrhoea
  • cold, clammy skin
  • a high temperature (fever)
  • rapid breathing
  • vomiting
  • low blood pressure (hypotension)
  • confusion
  • feeling faint and dizzy
  • losing consciousness

Septicaemia is a life-threatening condition and requires immediate treatment with antibiotics in hospital.

Scarring

In rare cases, impetigo may lead to some scarring. However, this is more often the result of someone scratching at blisters, crusts or sores. The blisters and crusts themselves should not leave a scar if left to heal.

The red mark left after the crusts and blisters clear up should also disappear by itself. The time it takes for the redness to disappear can vary between a few days and a few weeks.

Staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome (SSSS) is a serious skin condition in which one of the causes of impetigo – Staphylococcus bacteria – releases a toxin (poison) that damages the skin.

This leads to extensive blistering that looks like the skin has been scalded with boiling water.

Other symptoms of SSSS include:

  • painful skin
  • a high temperature (fever)
  • large areas of skin peeling off or falling away
  • redness of the skin which usually spreads across the entire body

SSSS usually requires immediate treatment in hospital with antibiotics given directly into a vein (intravenously).

Post-streptococcal glomerulonephritis

Post-streptococcal glomerulonephritis is an infection of the small blood vessels in the kidneys. It's a very rare complication of impetigo.

The symptoms of post-streptococcal glomerulonephritis include:

  • a change in the colour of your urine to a reddish-brown or cola colour
  • swelling of the abdomen (tummy), face, eyes, feet and ankles
  • a rise in blood pressure
  • visible blood in your urine
  • a reduction in the amount of urine you would normally produce

People with post-streptococcal glomerulonephritis will usually require immediate hospital treatment so their blood pressure can be carefully monitored and controlled.

Post-streptococcal glomerulonephritis can be fatal in adults, although deaths in children are rare.

Prevention

As impetigo is a highly contagious condition, it is important to take precautions to reduce the risk of the infection spreading.

Stopping the infection spreading

The advice below can help to prevent the spread of the infection to other people or to other areas of the body:

  • Stay away from work, school, nursery or playgroup until the sores have dried up, blistered or crusted over, or until 48 hours after starting treatment.
  • Don't share flannels, sheets or towels with anyone who has impetigo, and wash them at a high temperature after use.
  • Wash the sores with soap and water, and cover them loosely with a gauze bandage or clothing if possible.
  • Avoid touching the sores, or letting others touch them, whenever possible.
  • Don't scratch the affected areas. It may help to ensure your or your child's nails are kept clean and short to reduce the risk of further damage caused by scratching.
  • Avoid contact with newborn babies, preparing food, playing contact sports, or going to the gym until the risk of infection has passed (when the rash has crusted over, or after at least 48 hours of treatment with antibiotics).
  • Wash your hands frequently, particularly after touching infected skin.
  • Washable toys should also be washed. Wipe non-washable soft toys thoroughly with a cloth that has been wrung out in detergent and warm water and allowed to dry completely.

If you think that the infection has spread to someone else, make sure they are seen by a GP as soon as possible.

Preventing re-infection

To reduce the risk of impetigo returning, make sure any cuts, scratches or bites are kept clean, and ensure any condition that causes broken skin, such as eczema, is treated promptly.

If you develop impetigo frequently, your doctor may suggest taking a swab from around your nose to see if you carry staphylococcal bacteria inside your nose. These bacteria can live in the noses of some people without causing problems, although they can lead to impetigo if they infected broken skin nearby.

If you are found to carry these bacteria, you may be prescribed an antiseptic nasal cream to apply several times a day for five to 10 days in an attempt to clear the bacteria and reduce the chances of impetigo recurring.

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