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.
There are two types of impetigo:
- non-bullous impetigo, which typically affects the skin around the nose and mouth, causing sores to develop that quickly burst to leave a yellow-brown crust
- bullous impetigo, which typically affects the trunk (the central part of the body between the waist and neck), causing fluid-filled blisters (bullae) to develop that burst after a few days to leave a yellow crust
Both types of impetigo may leave behind some red marks when the crusts have cleared up, but these will usually improve over the following days or weeks.
Read more about the symptoms of impetigo.
Seeking medical advice
Speak to your GP if you think you or your child may have symptoms of impetigo.
Impetigo is not 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.
What causes impetigo?
Impetigo is caused by bacteria infecting the outer layers of skin.
The bacteria can infect the skin in two main ways:
- through a break in otherwise healthy skin, such as a cut, insect bite or other injury
- through skin damaged by another underlying skin condition, such as scabies or eczema
Once someone is infected with the bacteria, the infection can be spread easily through close contact, such as through direct physical contact, or by sharing towels or flannels.
Read more about the causes of impetigo.
Who is affected
Impetigo can affect people of any age, but it tends to affect children more often than adults.
Every year in the UK, around one in every 35 children up to four years of age and around one in every 60 children between four and 15 years of age will develop impetigo.
Non-bullous impetigo is the most common type of impetigo, accounting for more than 70% of cases. Bullous impetigo is most common in babies, although it can affect older children and adults too.
How impetigo is treated
Impetigo usually gets better without treatment in around two to three weeks, but 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.
During treatment, it's important to take precautions to minimise the risk of impetigo spreading to other people or other areas of the body, such as by:
- not touching the sores whenever possible
- washing your hands regularly
- not sharing flannels, sheets or towels
- staying away from work, school, nursery or playgroup until the sores have dried up or treatment has been continuing for at least 48 hours
Most people are no longer contagious after 48 hours of treatment or once their sores have dried and healed.
Read more about treating impetigo and preventing the spread of impetigo.
Impetigo is rarely serious, but in some cases the infection can spread to other areas of the body and cause problems such as cellulitis and scarlet fever.
In very rare cases, impetigo may lead to some scarring, particularly if you scratch at the blisters, crusts or sores.
Read more about the possible complications of impetigo
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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.
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.
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.
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.
In addition to the situations mentioned above, there are a number of other factors that can increase your chances of developing impetigo. These include:
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- 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
Impetigo is not usually serious and usually clears up without treatment after two to three weeks.
But treatment can help clear up the infection more quickly (usually in around seven to 10 days) and can reduce the risk of the infection being passed on to others.
If impetigo is confirmed, it can usually be effectively treated with antibiotics, which may be prescribed in the form of a cream (topical antibiotics) or as tablets (oral antibiotics).
If the infection is being caused by an underlying skin condition, such as eczema, this may also need to be treated.
Read more about the causes of impetigo.
For mild cases of impetigo that cover a small area, antibiotic cream is often recommended. This will usually need 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 is 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 and itchiness in the area where the cream is applied.
If symptoms have not improved after seven days of starting treatment, speak to your GP about other possible treatment options.
Antibiotic tablets may be prescribed if the infection is more severe and widespread, or if the symptoms do not improve after using antibiotic cream. These will 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 is very important that the course is finished even if the symptoms clear up before you have taken all the tablets.
Common side effects of oral antibiotics include feeling sick, vomiting and diarrhoea.
Speak to your GP if your symptoms have not 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, does not 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 bacteria 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. Read more about preventing impetigo.
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Staying away from others
To reduce the risk of spreading impetigo to others, you or your child you stay away from work, school or nursery until either:
- after 48 hours of treatment starting
- after the sores have stopped blistering or crusting
Once the crusts have cleared, they may leave a red mark on the skin. However, impetigo is not infectious by this stage and the redness will usually clear up in a few days or weeks.
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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 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 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 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 (a type of sepsis) is a bacterial infection of the blood. It can cause:
- cold, clammy skin
- a high temperature (fever)
- rapid breathing
- low blood pressure (hypotension)
- feeling faint and dizzy
- losing consciousness
Septicaemia is a life-threatening condition and requires immediate treatment with antibiotics in hospital.
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 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.
The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
As impetigo is a highly contagious condition, it is very important to take hygiene precautions to stop the infection spreading to other people.
The advice below will help to prevent the spread of infection.
- Keep children off nursery, playgroup or school until their sores have dried up, blistered or crusted over or until 48 hours after starting treatment.
- Don't share flannels, sheets or towels with infected people, 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.
- Don't touch the sores.
- Wash your hands frequently, particularly after touching infected skin.
- Avoid contact with newborn babies until the risk of contagion has passed (when the rash has crusted over, or after at least 48 hours of treatment with antibiotics).
- 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.
- Treat suspected or confirmed cases quickly.
- Cover cuts and grazes with a plaster or dressing.
To prevent the impetigo returning, keep cuts and scratches clean, and ensure that any condition that causes broken skin, such as eczema, is treated promptly.
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Last Updated: 12/02/2015 09:21:21