Scarlet fever is a bacterial infection that produces a distinctive red, sandpaper-textured rash across the body. It’s caused by the same bacteria behind strep throat, group A Streptococcus, but occurs when the strain releases a toxin that triggers the characteristic skin changes. It most commonly affects children between 5 and 15 years old and is fully treatable with antibiotics.
What Causes It
Scarlet fever develops when a particular strain of group A Streptococcus produces toxins called pyrogenic exotoxins during a throat infection. These toxins act as “superantigens,” meaning they activate a far larger number of immune cells than a normal infection would. The result is a flood of inflammatory signals throughout the body, which causes the fever, the rash, and the flushed appearance that gives the illness its name.
Not every case of strep throat turns into scarlet fever. Only strains that produce these specific toxins cause the rash. You can also develop some immunity to the toxin after an episode, which is why scarlet fever is less common in adults, though it’s not impossible to get it more than once.
How It Spreads
Scarlet fever spreads the same way as strep throat: through respiratory droplets when an infected person coughs or sneezes, or through direct contact with mucus or saliva. Sharing cups, utensils, or towels can also transmit the bacteria. A person is contagious from the time symptoms appear until they’ve been on antibiotics for at least 12 to 24 hours. Without treatment, someone can remain contagious for two to three weeks even after symptoms improve.
Recognizing the Symptoms
Scarlet fever typically starts like a standard strep throat infection: sore throat, fever (often above 101°F), headache, and sometimes nausea or vomiting. Within one to two days, the rash appears.
The rash usually begins on the neck and chest before spreading to the rest of the body. It looks like a sunburn covered in tiny raised bumps, and it feels distinctly rough, like sandpaper. Pressing on the rash briefly turns the skin white. The rash tends to be more intense in skin folds, particularly the armpits, elbows, and groin, where it can form dark red lines called Pastia’s lines.
The face often looks flushed, but the area around the mouth stays pale, creating a noticeable contrast. The tongue goes through its own progression: early in the illness it develops a whitish coating, then sheds that coating to reveal a swollen, red, bumpy surface often called “strawberry tongue.” This tongue change is one of the most recognizable signs of scarlet fever.
Skin Peeling During Recovery
After the rash fades, usually within about a week, the skin begins to peel. This peeling is most noticeable on the fingertips, toes, and groin area, and it can last for several weeks. It looks similar to skin peeling after a sunburn. The peeling itself isn’t painful or dangerous. It’s simply the body shedding the skin layers that were affected by the toxin. No special creams are needed, though gentle moisturizers can ease any discomfort.
How It’s Diagnosed
Diagnosis usually starts with a rapid strep test, which involves swabbing the back of the throat. Modern rapid tests are highly accurate, with sensitivity around 99% and specificity above 97%, meaning false results are uncommon. If the rapid test is negative but the doctor still suspects strep based on the rash and other symptoms, a throat culture (the gold standard) can confirm the diagnosis within one to two days.
The combination of a positive strep test with the sandpaper rash and strawberry tongue is usually enough to diagnose scarlet fever confidently.
Treatment and Timeline
Penicillin or amoxicillin is the first-line treatment, typically prescribed as a 10-day oral course. The full course needs to be completed even though symptoms usually improve within a few days. For people with a penicillin allergy, several alternatives are available, including certain antibiotics that can be taken for as few as 5 days.
Most children start feeling noticeably better within 24 to 48 hours of starting antibiotics. The fever usually breaks first, followed by gradual improvement in the sore throat. The rash fades over the course of a week, and then the peeling phase begins. From start to finish, the active illness lasts roughly 7 to 10 days, with peeling continuing for a few weeks afterward.
Children can generally return to school or daycare after they’ve been on antibiotics for at least 24 hours and their fever has resolved.
Complications to Watch For
With prompt antibiotic treatment, complications are rare. The reason doctors emphasize finishing the full course of antibiotics, even after symptoms clear, is to prevent two serious immune-related conditions that can develop weeks after the initial infection.
The first is rheumatic fever, which can damage the heart valves. In the United States, an estimated 1% to 3% of people with untreated strep infections develop acute rheumatic fever, and nearly 60% of those cases progress to chronic heart valve disease. The second is a kidney condition called poststreptococcal glomerulonephritis, which causes inflammation in the kidneys and can lead to blood in the urine and swelling. Both of these complications are immune-mediated, meaning the body’s own immune response causes the damage after the infection itself has cleared.
More immediate complications, though uncommon, include ear infections, sinus infections, and abscesses around the tonsils.
Recent Trends in Scarlet Fever Cases
Scarlet fever has been making a quiet comeback globally. Multiple countries, including the United Kingdom, China, South Korea, and Singapore, have reported significant resurgences since 2011. In 2022, the World Health Organization flagged a marked increase in both scarlet fever and invasive group A strep infections across European countries. Japan saw a notable outbreak of severe strep infections in the first half of 2024, with 656 reported cases of a serious strep-related complication.
Interestingly, COVID-19 pandemic measures temporarily disrupted this trend. A 14-year surveillance study in Shanghai found that scarlet fever incidence dropped from about 17 cases per 100,000 people before the pandemic to roughly 5 per 100,000 afterward, likely because masking and social distancing also reduced strep transmission. Whether cases will climb back to pre-pandemic levels remains an open question, but the broader global trend over the past decade has been upward.