Background. Drug shortages are an increasing and worldwide problem. Oral antibiotics are one of the most used medicines worldwide and have recently been affected by drug shortages. Despite this, little is known about the impact of antibiotic shortages on clinical and prescribing practices. Aim. To explore the impact of oral antibiotic shortages on national antibiotic utilisation. Methods. A longitudinal study of oral antibiotic shortages and antibiotic utilisation was conducted using Australian reimbursement and regulatory data from January 2022 to December 2023. All nationally reimbursed oral antibiotics were included in the study. The number and duration of reported antibiotic shortages per product were determined for each active ingredient. The clinical impact was assessed using national utilisation in Defined Daily Doses per 100,000 inhabitants. Changes in trends were analysed using Joinpoint regression. Results. Shortages were reported for eighteen of the twenty-one (86%) oral antibiotics reimbursed in Australia. No clear relation between the number and duration of shortages was observed for most antibiotics. Changes in utilisation coinciding with shortages were observed for eight active ingredients. For cefaclor (-20% decrease in utilisation) and roxithromycin (-26% decrease), the impact of shortages is most clearly reflected by decreases in utilisation. For the other six, either minor or mixed changes in utilisation were observed. Conclusions. Antibiotic shortages were common in Australia during 2022 and 2023. The impact of shortages appears complex with various factors most likely influencing impact. Australia’s healthcare professionals seem successful in mitigating the effects of shortages on drug utilisation.