How long is impetigo contagious after starting antibiotics?

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Last updated: February 7, 2025View editorial policy

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From the Guidelines

Impetigo is typically considered contagious for 24 hours after starting antibiotics.

Key Considerations

  • The provided evidence primarily discusses Group A Streptococcal (GAS) infection, which is a common cause of impetigo 1.
  • While the evidence suggests that isolation for 24-48 hours after commencement of antibiotic therapy is frequently cited, the working party recommends 24 hours of effective therapy as appropriate for the majority of cases seen in hospitals 1.
  • It's essential to note that some cases, such as those with significant discharge of potentially infectious body fluids or high-risk shedding, may require longer isolation periods 1.
  • The evidence does not provide a clear distinction between different types of impetigo or antibiotic treatments, but 24 hours is a commonly cited guideline for contagiousness after starting antibiotics.

From the Research

Impetigo Contagious Period After Starting Antibiotics

  • The contagious period of impetigo after starting antibiotics is not explicitly stated in the provided studies 2, 3, 4, 5, 6.
  • However, it is known that impetigo is a highly contagious bacterial skin infection that can be spread through direct contact with the lesions or through contaminated items 3, 4, 5.
  • The use of antibiotics can help reduce the contagious period by treating the underlying bacterial infection, but the exact duration of contagiousness after starting antibiotics is not specified in the studies.
  • It is recommended to follow proper hygiene practices, such as washing hands frequently and avoiding close contact with others, to prevent the spread of impetigo 5, 6.
  • The treatment of impetigo with antibiotics can vary depending on the severity of the infection, the type of bacteria causing the infection, and the presence of antibiotic resistance 2, 3, 4, 5, 6.

Factors Affecting Contagious Period

  • The contagious period of impetigo may be influenced by factors such as the type of bacteria causing the infection, the severity of the infection, and the effectiveness of the antibiotic treatment 2, 3, 4, 5, 6.
  • The use of topical antibiotics, such as mupirocin and fusidic acid, may be effective in treating impetigo and reducing the contagious period, especially in cases of localized infection 2, 3, 5.
  • Oral antibiotics, such as amoxicillin/clavulanate and cephalexin, may be necessary for more severe or widespread infections, and can help reduce the contagious period by treating the underlying bacterial infection 2, 3, 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Impetigo: diagnosis and treatment.

American family physician, 2014

Research

Diagnosis and treatment of impetigo.

American family physician, 2007

Research

Impetigo: A need for new therapies in a world of increasing antimicrobial resistance.

Journal of clinical pharmacy and therapeutics, 2018

Research

Treatment of impetigo: a review.

Pediatric infectious disease, 1985

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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