Background Unlike most other Western countries where antibiotic prescribing has been declining, in Ireland outpatient antibiotic use is increasing, at a rate of 3% per year since 2000. The aim is to assess parental factors in high antibiotic use (three or more per year) in children aged three years.

Methods The study population consisted of 9793 three year olds and their parents from the National Longitudinal Growing up in Ireland Study of Children. Data collection included surveys with the parents which were carried out when the infant was three years of age. Antibiotic use was measured by parental recall.

Results 18.4% of children aged three had three or more courses of antibiotics in the previous 12 months. After adjusting for maternal age, household type, education and sex of the child, higher antibiotic use was more likely if the parent’s perceived the child to be in poor health (adjusted OR = 21.48, 95% CI = 15.01–31.31), the number of conditions the child had (adjusted OR = 1.99, 95% CI = 1.32–3.01), if the child was attending a crèche (adjusted OR = 1.45, 95% CI = 1.29–1.63 and if the parents had decided to delay visiting the GP to wait and see if the child got better (adjusted OR = 1.4, 95% CI = 1.20–1.63). Parental anxiety was not associated with increased antibiotic use (adjusted OR = 1.01, p = 1.06).

Conclusion Having free GP access, increasing number of health conditions, attending a crèche and perceived poor child health by the parents were significantly associated with using three or more courses of antibiotics in a 12-month period (p = 0.001). Surprisingly, intentionally delaying a GP visit by parents was also associated with increased antibiotic use among three year olds (p = 0.001). Consultations following several days of persistent symptoms resulted in parents expecting an antibiotic, highlighting a need to address concerns about duration and severity of illness.