What is impetigo?
Impetigo is a highly contagious skin infection which causes sores and blisters. It's very common and affects mainly children.
There are two types of impetigo:
- bullous impetigo, which causes large, painless, fluid-filled blisters
- non-bullous impetigo, which is more contagious than bullous impetigo and causes sores that quickly rupture (burst) to leave a yellow-brown crust
Read more about the symptoms of impetigo.
Impetigo that affects otherwise healthy skin is referred to as primary impetigo. If the infection is the result of another underlying skin condition, such as atopic eczema, it's referred to as secondary impetigo.
Read more information about the causes of impetigo.
Should I see my doctor?
Speak to your doctor if you or your child has symptoms of impetigo. Impetigo is not usually serious, but it can sometimes be confused with other skin conditions such as cellulitis, contact dermatitis and insect bites.
Your doctor may want to rule these out.
Read more about diagnosing impetigo.
Impetigo usually gets better on its own, without the need for treatment, within two to three weeks. However, antibiotic creams are usually recommended because the infection spreads easily.
Most people are no longer contagious after 48 hours of treatment, or once their sores have dried and healed.
To minimise the risk of impetigo spreading, it's also advisable to:
- avoid touching the sores
- wash your hands regularly
- not share flannels, sheets or towels
- keep children off nursery, playgroup or school until their sores have dried up
Who is affected
Impetigo usually affects children. This is due to environments, such as schools and nurseries, where the infection can easily be spread.
Impetigo can also affect adults, especially when people are living in a confined environment, such as an army barracks.
Non-bullous impetigo is the most common type of impetigo, accounting for more than 70% of cases.
Impetigo does not cause any symptoms until four to 10 days after the initial exposure to the bacteria. This means that people can easily pass the infection on to others without realising that they are infected.
The symptoms of bullous and non-bullous impetigo are described below.
The symptoms of bullous impetigo begin with the appearance of fluid-filled blisters, which usually occur on the trunk (the central part of the body from above the waist, but excluding the head and neck) or on the arms and legs.
The blisters may quickly spread, before bursting after several days to leave a yellow crust which heals without leaving any scarring.
The blisters aren't usually painful, but 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.
The symptoms of non-bullous impetigo begin with the appearance of red sores that usually occur around the nose and mouth. However, sometimes other areas of the face and the limbs can also be affected.
The sores quickly burst leaving thick, yellow-brown golden crusts. 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 of impetigo, such as a fever and swollen glands, are rare but can occur in more severe cases.
Impetigo is often caused by a type of bacteria called staphylococcus aureus. It can also be caused by the streptococcus pyogenes bacteria, usually in warmer climates.
Primary and secondary infection
An impetigo infection can occur when the bacteria invades otherwise healthy skin through a cut, insect bite or other injury. This is known as primary impetigo.
An infection can also occur when the bacteria invades the skin as a result of the skin barrier being disrupted by another underlying skin condition, such as head lice, scabies or eczema. This is known as secondary impetigo.
An impetigo infection can spread to other people through close 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 is thought to be more common in children because their immune system has not yet fully developed, making them more vulnerable to infections such as impetigo.
Impetigo is usually easy to diagnose based on your symptoms and by ruling out other skin conditions that have similar symptoms to yours. In some cases, further testing may be needed.
Some skin conditions with similar symptoms to impetigo are listed below.
- Cellulitis: a bacterial infection of the deep layers of skin and tissue that lie underneath the skin.
- Erysipelas: a bacterial skin infection that usually affects the face or limbs.
- Herpes simplex virus: a highly contagious virus, also known as the "cold sore virus", which can cause cold sores on the mouth and the genitals.
- Scabies: a contagious skin condition that causes intense itching.
- Ecthyma: a bacterial infection that affects the deep layers of the skin.
- Candidiasis: a fungal infection that causes redness of the skin and is common in areas such as the groin, under the arms, between the fingers and between skin folds.
- Dermatophytosis: a skin infection with symptoms that can include red, scaly areas.
- Chickenpox: a highly infectious condition that causes an itchy rash that blisters and crusts over.
- Shingles: an infection of a nerve and the area of skin around it. Symptoms of shingles include tingling, pain and a blotchy red rash along one side of the body.
Other conditions that impetigo might be confused with impetigo include atopic eczema, contact dermatitis and insect bites. The symptoms of impetigo are also sometimes similar to those of burns and scalds.
Further tests for impetigo are usually only required in cases where the infection:
- is severe or widespread
- does not respond to treatment
- keeps recurring (coming back)
In the above circumstances, a small area of affected skin will be gently wiped with a swab (like a large cotton bud) for testing.
The tests will help to rule out or confirm other skin conditions that may be responsible for your symptoms.
Read more information about how impetigo is treated.
Impetigo is not usually serious and will often clear up without treatment after two to three weeks.
However, if you or your child has symptoms, visit your doctor to rule out the possibility of other, more serious infections.
If impetigo is confirmed, it can usually be effectively treated with antibiotics which may be prescribed in the form of a cream (topical) or as tablets. With treatment, the infection should clear up after about seven to 10 days and the time that the person is infected will also be reduced.
Before applying antibiotic cream, wash any affected areas of skin with warm, soapy water.
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.
Antibiotic tablets (oral antibiotics) may be prescribed if the infection is severe and spreads rapidly, or the symptoms do not improve after using antibiotic cream.
A seven-day course of oral antibiotics is usually recommended. 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.
Side effects of oral antibiotics can include:
- stomach aches
- nausea (feeling sick)
- vomiting (being sick)
- diarrhoea (loose, watery stools)
- yeast infections, such as thrush (in women)
If the blisters continue to produce fluid it is a sign that they are still infectious. Impetigo stops being infectious after 48 hours of treatment starting. Therefore, if your child has impetigo they should be able to return to school or nursery:
- 48 hours after antibiotic treatment has started
- after the sores have stopped blistering or crusting
If symptoms have not improved within seven days of starting treatment, go back to your doctor for a follow-up appointment to discuss other treatment options.
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.
Complications of impetigo
Complications of impetigo are rare, but they can occur and occasionally be serious. Tell your doctor if your symptoms change or get worse.
Some complications are described below.
Cellulitis occurs when the infection spreads to a deeper layer of skin. It can cause symptoms of red, inflamed skin and fever and pain. It can be treated with antibiotics and paracetamol 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 (less than 1cm) red, droplet-shaped, scaly patches on the chest, arms, legs and scalp. Creams can be used to control the symptoms.
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 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 had at least five days of treatment with antibiotics.
Septicaemia (a type of sepsis) is a bacterial infection of the blood. It can cause symptoms of:
- cold, clammy skin
- a high temperature (fever) of 38C (100.4F) or above
- 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.
Post-streptococcal glomerulonephritis is an infection of the small blood vessels in the kidneys. It's a very rare complication.
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
- swelling of the face, eyes, feet and ankles
- a rise in blood pressure
- visible blood in the urine
- a reduction in the amount of urine you would normally produce
People with post-streptococcal glomerulonephritis will usually require immediate hospital treatment so that their blood pressure can be carefully monitored and controlled.
Post-streptococcal glomerulonephritis can be fatal in adults, although deaths in children are rare. Less than 1% of children die as a result of the condition.
In very 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 that is left should also disappear by itself. The time it takes for the redness to disappear can vary between a few days and a few weeks.