BACKGROUND: The inappropriate use of oral antibiotics contributes to antimicrobial resistance. Oral antibiotics are regularly used to treat moderate to severe acne vulgaris. Acne guidelines recommend oral antibiotics for a minimum duration of three months of daily exposure and to repeat treatment if acne recurs. It is unclear how long-term oral antibiotics for acne are prescribed in the United Kingdom, and how they contribute to antibiotic treatment failure and antimicrobial resistance. OBJECTIVES: The objectives of my thesis were to 1) systematically review evidence published in the literature on the association between oral antibiotics for acne and antibiotic treatment failure or infection caused by a resistant organism 2) to describe how people with acne are managed with oral antibiotics in UK primary care using the Clinical Practice Research Datalink (CPRD) over five years; and 3) to investigate the association between long-term oral antibiotics for acne and antibiotic treatment failure for common infections using the CPRD. RESULTS: Objective 1) Weak evidence was found in the literature for an association between antibiotic use for acne and subsequent increased rates of upper respiratory tract infections and pharyngitis. Objective 2) In the CPRD, a total of 217,410 people between the ages of 8 and 50 had a new acne diagnosis of which 96,703 (44.5%) people received 248,560 prescriptions for long-term oral antibiotics during a median follow up of 5.3 years (IQR 2.8- 8.5). People received a median of four (IQR 2-6) continuous course of antibiotic therapy (≥28days). The median duration of the first course of oral antibiotic prescribed after acne diagnosis was 56 days (IQR 50-93 days) and 18,127 (18.7%) were for 366 days (HR=1.84 (1.48,2.28)). CONCLUSIONS: Further work is needed to understand the consequences of using antibiotics for shorter periods than recommended in acne treatment guidelines. Findings suggest an association between oral antibiotics for acne and antibiotic treatment failure within five years. There is some evidence that trimethoprim is more strongly associated with antibiotic treatment failure and shorter durations of antibiotics for acne are associated with less antibiotic treatment failure.