Abstract
BACKGROUND: Systemic antibiotics for moderate-to-severe acne are commonly prescribed, but the optimal duration remains unclear. Prolonged use may increase recurrence rates and antibiotic resistance. This study evaluated the long-term effects of antibiotic duration on acne recurrence and microbial resistance. METHODS: This study included a single-center retrospective cohort of 240 patients (12-40 years) with moderate-to-severe acne treated with doxycycline or minocycline (2020-2023). Patients were stratified into groups by duration: short-term (6-12 weeks, n = 80), standard-term (13-16 weeks, n = 80), and prolonged (17-24 weeks, n = 80) groups. The primary outcome was the 12-month recurrence rate. Secondary outcomes included 12-week treatment success, scarring, adverse reactions, and resistance development (culture subset, n = 46). RESULTS: The 12-month recurrence rates increased in a duration-dependent manner: 23.8% (short-term duration), 35.0% (standard-term duration), and 46.3% (prolonged duration) (p < 0.001). The median recurrence-free survival was 9.2, 8.1, and 6.9 months, respectively (log-rank p < 0.001). Prolonged exposure independently predicted recurrence (adjusted hazard ratio (HR): 2.31, 95%CI 1.31-4.07, p = 0.004). The 12-week success rates were similar (73.8-76.3%, P=0.78). Scarring (21.3-22.5%, p = 0.97) and adverse events (27.5-31.3%, p = 0.83) did not differ. Tetracycline resistance was more frequent with prolonged exposure (42.9% vs. 13.3-17.6%, p = 0.032). CONCLUSION: Extended antibiotic therapy for acne was associated with an increased 12-month recurrence risk without improving short-term outcomes, consistent with guideline recommendations to limit duration and emphasize antimicrobial stewardship.