Scarlet fever !

Scarlet fever is a strep throat infection with a rough red rash and a strawberry tongue. Antibiotics cure it and prevent rheumatic fever.

Updated 2026-11-01

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Why it happens

What it is

An illness caused by toxin-producing strains of group A Streptococcus (Streptococcus pyogenes), usually from a throat infection, in which fever and pharyngitis are joined by a diffuse fine red rash that feels like sandpaper.

Who gets it

Mainly affects school-age children (roughly 5 to 15 years) and is uncommon under 3. It spreads in schools and crowded homes and shows periodic rises worldwide. In Latin America, including Colombia, untreated streptococcal infection still matters because of acute rheumatic fever and rheumatic heart disease.

Causes

Group A Streptococcus strains that produce pyrogenic (erythrogenic) exotoxins
Usually follows streptococcal pharyngitis or tonsillitis; less often a skin or wound infection
Spread by respiratory droplets and direct contact; incubation about 2 to 5 days

Risk factors

Age 5 to 15 years
Close contact with a person who has strep throat
Crowded settings: schools, day care, shelters, large households
Outbreaks in the community

Pathophysiology

Streptococci multiply in the tonsils and pharynx and release pyrogenic exotoxins that act as superantigens. The toxins cause widespread capillary dilation in the skin, giving the rash, and a systemic inflammatory response with fever. In some people, antibodies against streptococcal antigens later cross-react with heart, joint or kidney tissue, causing rheumatic fever or glomerulonephritis.

Classification

Pharyngeal scarlet fever (most common)
Surgical or wound scarlet fever (from a skin or wound infection)
Toxic or septic forms, now rare

Symptoms and signs

Sudden fever with sore throat; red tonsils, often with exudate, and tender neck lymph nodes
Fine red rash with a sandpaper feel, starting on the neck and chest and spreading over the trunk and limbs within 1 to 2 days
Flushed face with pallor around the mouth (circumoral pallor)
Rash more intense in skin folds (Pastia lines)
Strawberry tongue: white-coated at first, then bright red with prominent papillae
Headache, abdominal pain, vomiting and malaise
Peeling of the skin of fingertips, toes and groin as the rash fades

Diagnosis

Clinical: Fever, pharyngitis and the typical sandpaper rash with strawberry tongue, circumoral pallor and Pastia lines; ask about contacts with strep throat.
Tests: Rapid antigen detection test or molecular test on a throat swab; throat culture confirms when a rapid test is negative in a child. Antistreptolysin O (ASO) titres help only when looking for later complications such as rheumatic fever. Urinalysis if glomerulonephritis is suspected.
Imaging: Not needed for uncomplicated cases. Neck ultrasound or CT if an abscess is suspected; echocardiography if rheumatic carditis is suspected.

Differential diagnosis

Viral exanthems such as measles and rubella
Kawasaki disease (also strawberry tongue and peeling, but with conjunctivitis and prolonged fever)
Staphylococcal or streptococcal toxic shock syndrome
Staphylococcal scalded skin syndrome
Drug eruption
Infectious mononucleosis with rash

Goal of treatment

Eradicate group A Streptococcus to shorten the illness, prevent spread and, above all, prevent acute rheumatic fever and suppurative complications.

Treatment

Medical: Antibiotics: penicillin or amoxicillin are first choice for a full course; cephalosporins or macrolides are alternatives in penicillin allergy (macrolide and clindamycin resistance can occur).
Conservative: Supportive care: fluids, soft foods and antipyretic analgesics for fever and throat pain.
Follow-up: Reassessment if there is no improvement in 24 to 48 hours; watch for abscess, rheumatic fever and glomerulonephritis in the following weeks.
Lifestyle: Infection control: the child usually stays home from school or day care until afebrile and at least 12 to 24 hours after starting antibiotics; hand hygiene and not sharing utensils.

Complications

Suppurative: peritonsillar or retropharyngeal abscess, cervical lymphadenitis, acute otitis media, sinusitis
Acute rheumatic fever, with possible rheumatic heart disease
Post-streptococcal glomerulonephritis
Pneumonia, bacteraemia or invasive group A strep infection (rare)
Streptococcal toxic shock syndrome (rare)

Prognosis

With antibiotics, fever falls within a day or two and recovery is usually complete; the rash may take up to 2 to 3 weeks to fade with peeling. Serious complications are rare when treatment is prompt.

Prevention

Hand hygiene and covering coughs; not sharing cups or utensils
Prompt diagnosis and full antibiotic treatment of strep throat
Keeping sick children home until they are no longer contagious

Test yourself

Think of the answer, then tap the question to see it.

What organism causes scarlet fever?

Toxin-producing group A Streptococcus (Streptococcus pyogenes), usually after a throat infection.

How is the rash of scarlet fever classically described?

A fine red rash with a sandpaper texture, starting on the neck and chest, with Pastia lines, circumoral pallor and later peeling.

What is the main reason to treat scarlet fever with antibiotics?

To prevent acute rheumatic fever and suppurative complications, as well as to shorten illness and spread.

Which antibiotic class is first choice for scarlet fever?

Penicillins (penicillin or amoxicillin); group A strep has not shown penicillin resistance.

Which kidney complication can follow streptococcal infection?

Post-streptococcal glomerulonephritis, with haematuria, oedema and hypertension one to a few weeks later.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Scarlet fever (MedlinePlus (U.S. National Library of Medicine), 2024); Clinical Guidance for Scarlet Fever (Centers for Disease Control and Prevention (CDC), 2024).

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Representative model, for educational purposes only.

Palatine tonsils highlighted on the Durgical 3D model