What is the treatment for scarlet fever?

Treatment of Scarlet Fever

Oral Penicillin V (phenoxymethylpenicillin) 250-500 mg every 6-8 hours for 10 days is the first-line treatment for scarlet fever, as recommended by the Infectious Diseases Society of America and American Heart Association. 1

Antibiotic Selection Algorithm

First-Line Treatment

• Penicillin V remains the gold standard for treating scarlet fever caused by Group A Streptococcus (GAS) 1
• Dosing options include 250-500 mg every 6-8 hours, or alternatively 500 mg twice daily or 250 mg three times daily for 10 days 1
• The patient becomes non-contagious after 24 hours of antibiotic therapy 1

For Penicillin-Allergic Patients

• First-generation cephalosporins are recommended for patients without immediate hypersensitivity to β-lactam antibiotics 1
• Macrolides are recommended for patients with true penicillin allergy, though be aware that some strains of Streptococcus pyogenes may be resistant to macrolides 1
• Never use sulfonamide antibiotics, as they are associated with increased disease severity and mortality in streptococcal infections 1

Co-Amoxiclav (Augmentin) - Limited Role

• Co-amoxiclav should only be considered if there is documented treatment failure with penicillin, though this is uncommon 1
• The American Heart Association recommends against using co-amoxiclav as first-line treatment due to its broader spectrum, higher risk of antibiotic resistance, and higher rates of gastrointestinal side effects (particularly diarrhea, with a number needed to harm of 10) 1
• If used: Children receive 40 mg/kg/day of the amoxicillin component in 2-3 divided doses for 10 days; adults receive 500 mg twice daily for 10 days 1

Critical Timing Considerations

Antibiotics can be started up to 9 days after symptom onset and still prevent rheumatic fever, though early treatment reduces the infectivity period and morbidity 1. This provides a therapeutic window that allows time for proper diagnosis while still preventing serious complications.

Diagnostic Confirmation Before Treatment

• Throat culture or rapid antigen detection test (RADT) should be performed to confirm GAS infection before initiating antibiotic therapy 1
• Throat culture remains the reference standard, with specimens obtained from the posterior pharynx and tonsillar surfaces 1
• However, in patients with typical clinical features (fever ≥38°C, distinctive sandpaper-like rash, sore throat, strawberry tongue), immediate antibiotic prescription is appropriate to reduce complications and spread of infection 2, 3

Symptomatic Management

• Antipyretics may be used for symptomatic relief of fever but do not replace the need for antibiotics 1
• Never use aspirin for fever control in children under 16 years due to risk of Reye's syndrome 1

Monitoring and Follow-Up

• Monitor for clinical improvement within 48-72 hours of starting antibiotics 1
• If symptoms persist beyond 3-5 days of antibiotic therapy, reassess the diagnosis and consider alternative pathogens 1
• Post-treatment throat cultures are not routinely recommended unless symptoms persist or recur 1

Management of Close Contacts

• Routine throat cultures or treatment for asymptomatic household contacts is generally not necessary 1
• In outbreak situations, throat cultures should be performed for all patients and only those with positive throat cultures should be treated 1

Infection Control

• Patients should be isolated for a minimum of 24 hours of effective antibiotic therapy 1
• Healthcare workers must use disposable gloves and aprons when in contact with the patient, with strict hand hygiene using soap and water or alcohol hand rub before and after patient contact 1

Common Pitfalls to Avoid

• Do not delay treatment in typical presentations while waiting for culture results, as early treatment prevents serious complications including acute rheumatic fever, glomerulonephritis, endocarditis, and meningitis 3, 4
• Do not use sulfonamides despite their activity against streptococci, as they worsen outcomes 1
• Do not assume the rash must follow a typical distribution - atypical presentations can occur, including involvement limited to hands and feet 5
• Be aware of oral manifestations ("strawberry tongue" or "raspberry tongue") that may be first noted by dental professionals 3