Background Anti-microbial resistance (AMR) is a global threat to public health and antibiotics are often unnecessarily prescribed for acute respiratory tract infections (ARTIs) in general practice. We aimed to investigate why general practitioners (GPs) continue to prescribe antibiotics for ARTIs despite increasing knowledge of their poor efficacy and worsening antimicrobial resistance. Methods We used an explorative qualitative study design. Thirteen GPs were recruited through purposive sampling to represent urban and rural settings and years of experience. They were based in general practices within the Mid-West of Ireland. GPs took part in semi-structured interviews that were digitally audio recorded and transcribed. Results Three main themes and three subthemes were identified. Themes include (1) non-comprehensive guidelines; how guideline adherence can be difficult, (2) GPs under pressure; pressures to prescribe from patients and perceived patient expectations and (3) Unnecessary prescribing; how to address it and the potential of public interventions to reduce it. Conclusions GPs acknowledge their failure to implement guidelines because they feel they are less usable in clinical situations. GPs felt pressurised to prescribe, especially for fee-paying patients and in out of hours settings (OOH), suggesting the need for interventions that target the public’s perceptions of antibiotics. GPs behaviours surrounding prescribing antibiotics need to change in order to reduce AMR and change patients’ expectations. Electronic supplementary material The online version of this article (10.1186/s12875-019-0917-8) contains supplementary material, which is available to authorized users.