Impetigo: Symptoms, Diagnosis, Treatment, and More

Impetigo is an extremely contagious skin infection caused by bacteria, usually either the staph or strep bacteria. It affects the top layer of the skin, causing sores (nonbullous) or blisters (bullous). (1)

The condition is more common in children and occurs when bacteria enters the skin through an opening or wound. Impetigo can also develop after skin-to-skin contact with an infected person, or from touching items contaminated with the bacteria. (2)

You can learn how to recognize the signs and symptoms of impetigo and take steps to help stop its spread.

If you don’t treat impetigo with antibiotics, it is possible to pass the infection to others.

For this reason, see a doctor if you suspect impetigo or if you develop any unusual skin problems. Common signs of this infection include: (3)

Skin Sores

Impetigo skin sores can occur on any part of the body, including the face, the lips, the arms, and the legs. Some people have a mild case and only develop one lesion. But other times, impetigo is more severe and many sores or blisters develop. (3)

These lesions may cluster together in one area of the body, or be scattered across different parts of the body.

Impetigo sores can spread to other parts of the body when an infected person touches or scratches her lesions and then touches other areas of her skin. That’s why it’s important to wash lesions with soap and water and keep them covered. (3)

Blisters

While some people develop skin sores, which are a common symptom of impetigo, others develop yellow, fluid-filled blisters.

Blisters are often accompanied by redness on the surrounding skin. You may have a single blister or multiple blisters. A blister may break open and ooze with pus. Once treatment with antibiotics begins, healing can progress within days. (1)

Crusting

Whether you have sores or blisters, the skin will eventually break open. Crusting or a thick scab forms over the broken skin. The appearance of the crusts can be yellow, brown, or honey-colored. (2)

Swelling

Sometimes swelling can occur near the skin infection due to swollen lymph nodes, particularly in children.

Itching

Impetigo lesions can also itch. It’s important that you don’t scratch sores or blisters. This can worsen the infection and spread the bacteria to other parts of your body.

Pain

Even though impetigo can be unsightly and cause itching, it isn’t always painful. And when soreness does occur, it’s generally mild. (2)

Untreated impetigo, however, can penetrate deeper into the skin and cause painful sores or blisters called ecthyma, explains Rick Pescatore, DO, the director of research at Crozer-Keystone Health System Emergency Medicine in Philadelphia. This can sometimes lead to a life-threatening situation. (3)

Scarring

Impetigo often heals without permanent skin scarring, says Dr. Pescatore. But scarring can occur when deeper lesions develop.

It’s not uncommon to have a minor skin rash or tiny bumps on the skin. Many rashes do not require medical attention. But impetigo is contagious, so if you believe you have it, strongly consider seeing a medical professional. (2)

“Generally speaking, your primary care doctor is the best first step for your rash, but rashes that are particularly uncomfortable or rapid in onset are typically appropriate to be seen in urgent care,” says Pescatore. “Patients who develop rashes that are particularly painful, accompanied by skin sloughing, fever, or body aches, or who have darker rashes that don’t fade when pressure is applied to the skin should consider going to the closest emergency department for evaluation.”

Why Your Doctor May Order a Skin Culture to Make an Impetigo Diagnosis

Because impetigo is a common skin condition, most doctors can diagnose the infection by looking at the skin; diagnostic tests aren’t typically needed for confirmation. But in some cases, your doctor may order a skin culture swab of the skin. (5)

Skin cultures are used to help doctors identify specific germs that cause problems on the skin. This type of test can help determine whether your skin problem is caused by bacteria, fungus, or a virus. (7)

With a proper diagnosis, your doctor will know the best way to treat the condition.

Your doctor may recommend a skin culture for open sores as well as for rashes that appear infected.

This is a simple procedure. Your doctor will collect a skin sample by swabbing a sore or a blister. The sample is sent to a laboratory where it is examined.

Sometimes a doctor will order a blood test. This may occur when impetigo has spread to multiple places on a person’s skin. (3)

To help the infection heal, your doctor will likely prescribe an antibiotic treatment. This can include topical antibiotics for mild infections, or an oral antibiotic for a more widespread infection.

Antibiotics used to treat impetigo include the topical mupirocin (Bactroban) and the oral medicines amoxicillin and clavulanate (Augmentin) and cephalexin (Keflex). (8)

You’re no longer contagious after one to two days of starting antibiotics. And in most cases, you don’t need to follow up with your doctor. (3)

Sores and blisters start to heal in a few days. Complete healing takes about one week, sometimes without permanent scarring. (1)

The prognosis with or without treatment is positive, but contact your doctor again if you feel that your antibiotic isn’t working. Signs of an ineffective antibiotic include: (9)

Blisters and Sores Grow in Size If you start antibiotic treatment and notice your blisters increasing in size after a couple of days, speak with your doctor. There’s a chance that your antibiotic isn’t working to stop the infection.

Development of New Sores or Blisters You should not develop any new sores or blisters once you start antibiotic treatment. Call your doctor if new skin lesions form.

Healing Takes Longer Than One Week Speak with your doctor if your sores or blisters have not healed after one week. Impetigo isn’t a dangerous condition, with most people healing two to four weeks without treatment. Treatment, however, speeds the healing process. If your sores don’t heal, you may need a different antibiotic.

Your Condition Worsens Also, speak with your doctor if you or your child’s condition worsens after starting antibiotics. This can include developing pain around sores or blisters, or if you have increased redness or swelling around sores.

Given the highly contagious nature of impetigo, it’s important to keep children home from school or day care until they’re no longer contagious; that means for at least a few days after starting antibiotics. (3)

Remember, without medication, it can take up to four weeks for sores and blisters to heal on their own. (3) If you or your child has a single lesion and you choose to skip the doctor and self-treat at home, keep the sore loosely covered with petrolatum (Vaseline or Aquaphor) and gauze until it completely heals.

Clean and apply an over-the-counter topical antibiotic to the sore daily, and then wash your hands afterward. (3)

Take the same precautions if you receive a prescription antibiotic. Avoid skin-to-skin contact, keep the lesions covered, disinfect your home daily, and wash your hands frequently. (2)

While self-treatment is an option for mild impetigo, it is best to see a doctor to prevent complications and infecting others.

Because impetigo is an infection, there’s the risk of bacteria infecting the tissue beneath the skin and traveling to the lymph nodes and the bloodstream. This is known as cellulitis, and symptoms include hard, swollen skin, pain, cold sweats, nausea, drowsiness, and a fever. (10)

When strep causes impetigo, there’s also the risk of post-streptococcal glomerulonephritis. This is when inflammation occurs in the kidneys, leading to kidney damage if not treated. (11)

“Fortunately, this is a relatively rare phenomenon in developed countries, in part due to improved hygiene and antibiotic processes, and largely driven by a drift of bacterial strains that no longer resemble the body’s own antigens,” says Pescatore.

Scarring is another complication of impetigo. This can occur when ulcerations penetrate deep into the skin, or if you scratch or pick at lesions. (3)

See a doctor if you have symptoms of cellulitis or kidney damage. Symptoms of kidney problems include pink or brown-colored urine, foamy urine, fluid retention, and high blood pressure. (11)

Just because impetigo is a common bacterial skin infection doesn’t mean you should ignore symptoms or let the condition resolve itself.

Understanding the signs and symptoms of this condition, and making a doctor’s appointment early, promotes faster healing. And as a result, you’re less likely to spread the infection to others or deal with potentially life-threatening complications.