“Indian fire” is a colloquial name for impetigo, a highly contagious bacterial skin infection that affects the outermost layer of skin. The term has been used for generations in parts of the United States, particularly in rural and Southern communities, though the medical name is simply impetigo. It most often shows up in children between ages 2 and 5, though anyone can get it.
What Impetigo Looks and Feels Like
The infection typically starts as small red spots that quickly develop into blisters. These blisters break open and leave behind a distinctive honey-yellow or golden crust on the skin. The sores can be itchy, sometimes painful, and tend to cluster around the nose, mouth, hands, and forearms, though they can appear anywhere on the body.
There are two main forms. The more common type, non-bullous impetigo, produces those classic crusty, oozing sores that gave the infection its folk name. The less common bullous form creates larger, fluid-filled blisters that look almost like burns. These blisters tend to appear on the trunk and don’t rupture as quickly, but eventually break and leave a thin crust behind. Both forms spread easily from one area of the body to another through scratching or touching.
What Causes It
Impetigo is caused by bacteria that enter through a break in the skin. Even a tiny scratch, insect bite, or patch of eczema can provide an opening. The two bacteria responsible are Staphylococcus aureus (staph) and Streptococcus pyogenes (strep). Staph is the more common culprit today, but strep causes a significant number of cases, and sometimes both bacteria are involved at once.
The infection thrives in warm, humid conditions. This is one reason it spreads more readily during summer months and in tropical climates. Crowded living situations, close physical contact in daycares and schools, and shared towels or clothing all increase the risk. Children are especially vulnerable because they get more cuts and scrapes, and their immune systems are still developing.
How It Spreads
Impetigo is one of the more contagious skin infections. It passes from person to person through direct contact with the sores or with items that have touched them, like towels, bedding, or clothing. A child can also spread it to other parts of their own body by scratching a sore and then touching somewhere else.
The infection remains contagious until treatment begins. Once antibiotics are started, the ability to transmit the bacteria drops significantly. According to CDC guidance and the American Academy of Pediatrics, children can return to school or daycare at least 12 hours after starting antibiotic treatment, as long as they appear well and their sores are covered. In outbreak situations or healthcare settings, a 24-hour window is recommended instead.
Treatment
Most cases of impetigo clear up with a topical antibiotic ointment applied directly to the sores. Clinical guidelines recommend topical treatment for 5 to 7 days when the infection is limited to a small area. A commonly prescribed option is mupirocin ointment, applied three times daily for five days. Research across 22 randomized trials involving nearly 900 patients found that topical antibiotics work just as well as oral antibiotics for uncomplicated cases, and mupirocin actually performed slightly better than some oral options.
Oral antibiotics become necessary when the infection is widespread, when sores are deep, or when topical treatment hasn’t worked. Before applying any medication, gently washing the crusted areas with warm water and mild soap helps the antibiotic penetrate the skin more effectively. You don’t need to scrub aggressively. Just soften and remove loose crust.
Most cases heal within one to three weeks with proper treatment. The sores rarely leave scars, since impetigo only affects the very surface of the skin. Without treatment, the infection can linger for weeks and continue spreading.
Preventing Spread at Home
If someone in your household has impetigo, a few practical steps make a real difference. Give them their own towel and washcloth, and wash these in hot water after each use. Wash bedding frequently. Have them avoid touching or scratching the sores, and keep the affected areas covered with a loose bandage when possible. Regular handwashing with soap is the single most effective way to prevent transmission to other family members.
Keeping fingernails trimmed short helps reduce the bacteria that collect underneath them, which matters because scratching is the primary way the infection spreads to new areas. If your child has a cut, scrape, or insect bite, cleaning it promptly and keeping it covered reduces the chance bacteria can enter in the first place.
Potential Complications
Impetigo is usually mild and resolves without lasting problems. In rare cases, however, untreated strep-related impetigo can trigger a kidney condition called post-streptococcal glomerulonephritis, where the body’s immune response to the bacteria causes inflammation in the kidneys. Symptoms include dark or cola-colored urine, swelling in the face or legs, and reduced urine output. This typically appears one to two weeks after the skin infection.
Another possible complication is ecthyma, a deeper form of the infection that extends below the surface layer of the skin. Ecthyma sores are more painful, form thick crusts, and can leave scars. This is more likely when impetigo goes untreated for an extended period or when the immune system is compromised. Both complications are uncommon with timely treatment.