Natural history of non-bullous impetigo: a systematic review of time to resolution or improvement without antibiotic treatment

BACKGROUND: Non-bullous impetigo is typically treated with antibiotics. However, the duration of symptoms without their use has not been established, which hampers informed decision making about antibiotic use. AIM: To determine the natural history of non-bullous impetigo. DESIGN AND SETTING: Systematic review. METHOD: The authors searched PubMed up to January 2020, as well as reference lists of articles identified in the search. Eligible studies involved participants with impetigo in either the placebo group of randomised trials, or in single-group prognostic studies that did not use antibiotics and measured time to resolution or improvement. A modified version of a risk of bias assessment for prognostic studies was used. Outcomes were percentage of participants who had either symptom resolution, symptom improvement, or failed to improve at any timepoint. Adverse event data were also extracted. RESULTS: Seven randomised trials (557 placebo group participants) were identified. At about 7 days, the percentage of participants classified as resolved ranged from 13% to 74% across the studies, whereas the percentage classified as ‘failure to improve’ ranged from 16% to 41%. The rate of adverse effects was low. Incomplete reporting of some details limited assessment of risk of bias. CONCLUSION: Although some uncertainty around the natural history of non-bullous impetigo remains, symptoms resolve in some patients by about 7 days without using antibiotics, with about one-quarter of patients not improving. Immediate antibiotic use may not be mandatory, and discussions with patients should include the expected course of untreated impetigo and careful consideration of the benefits and harms of antibiotic use.