What is the treatment for a patient with a rash and confirmed streptococcal (strep) infection?

Treatment for Rash with Confirmed Streptococcal Infection

Determine if the Rash is Post-Streptococcal or Active Infection

If the patient has already completed a full course of appropriate antibiotics for streptococcal infection and the rash appeared after treatment, provide supportive care only—additional antibiotics are not needed. 1

Post-Streptococcal Rash (After Adequate Treatment)

• Supportive care is the primary treatment, including antihistamines for itching, antipyretics/analgesics for discomfort, and skin moisturizers for dryness 1
• Post-streptococcal rashes are immunologically mediated reactions that typically develop after the acute infection has been adequately treated and are self-limiting 1
• The rash is not a sign of treatment failure or ongoing infection if the patient completed an appropriate antibiotic course 1

Do not prescribe additional antibiotics unless:

• The initial treatment course was incomplete 1
• Signs of persistent or recurrent streptococcal infection are present 1
• Secondary bacterial infection of the rash is suspected 1

Active Streptococcal Infection with Rash (Scarlet Fever)

If the patient has confirmed streptococcal infection (by culture or rapid antigen detection test) and has not yet been treated or completed treatment:

First-Line Antibiotic Treatment

Prescribe penicillin V 250 mg four times daily or 500 mg twice daily for 10 days, or amoxicillin 500 mg twice daily for 10 days. 2 For children, amoxicillin is often preferred due to better palatability 3

• Penicillin remains the drug of choice due to proven efficacy in preventing rheumatic fever, narrow spectrum, safety profile, and low cost 3, 2
• A full 10-day course is mandatory to ensure eradication of Group A Streptococcus from the pharynx and prevent acute rheumatic fever 3, 1, 4
• Benzathine penicillin G 1.2 million units intramuscularly as a single dose is an alternative for adults, particularly when compliance is a concern 2

Alternative Antibiotics for Penicillin-Allergic Patients

For patients with penicillin allergy, use cephalexin, clindamycin, azithromycin, or clarithromycin. 1

• Azithromycin is FDA-approved for streptococcal pharyngitis as an alternative when first-line therapy cannot be used 5
• Important caveat: Azithromycin should not be relied upon to prevent rheumatic fever, as data establishing its efficacy in subsequent prevention are not available 5
• Susceptibility testing should be performed when using azithromycin, as some strains are resistant 5
• Erythromycin is acceptable but may cause cholestatic hepatitis, particularly in pregnant women who should not receive the estolate formulation 3

Critical Treatment Principles

• Therapy can be safely initiated up to 9 days after symptom onset and still prevent acute rheumatic fever, allowing flexibility in awaiting confirmatory test results 3, 2
• Antibiotics shorten symptom duration by only 1-2 days; the primary benefit is prevention of complications including acute rheumatic fever, peritonsillar abscess, and spread during outbreaks 2
• Cultures should be taken following completion of treatment to determine whether streptococci have been eradicated 4

When to Reevaluate

Reassess patients with:

• Worsening rash despite supportive care 1
• Development of systemic symptoms or signs of secondary bacterial infection 1
• Symptoms persisting or worsening 5 days after antibiotic initiation, which may indicate complications such as peritonsillar abscess or parapharyngeal abscess 2
• New symptoms suggesting post-streptococcal complications 1

Common Pitfall to Avoid

Do not prescribe additional antibiotics for post-treatment rashes that appear after completing a full 10-day course—this represents an immunologic reaction, not treatment failure or persistent infection 1. The exception is if there are clear signs of incomplete initial treatment, recurrent infection, or secondary bacterial superinfection 1.