To investigate the epidemiology of influenza-like illness (ILI) by general practice and patient characteristics, and explore whether sociodemographic variables or comorbidities affect antiviral or antibiotic prescribing. Open cohort study. A representative sample of 550 Australian general practices contributing data to the MedicineInsight programme. 4 228 149 patients of all age groups who had at least one consultation between 2015 and 2017. Median age was 37 years (Interquartile range: 21-57), 54.4% women, 16.4% aged ≥65 years, 2.2% Aboriginal or Torres Strait Islander, 17.6% had a chronic disease and 18.1% a mental health condition. ILI consultation rates (per 1000 consultations) were calculated using all ILI diagnoses for all clinical encounters with a general practitioner between 2015 and 2017. Antiviral and antibiotic prescribing for ILI cases were investigated and logistic regression models adjusted for practice and patient characteristics used to analyse associations. ILI consultation rates in 2017 were higher than in previous years. Antiviral prescribing increased from 20.6% in 2015, to 23.7 in 2016 and 29.7% in 2017, while antibiotic prescribing decreased from 30.3% to 28.0% and 26.7%, respectively (p<0.05 in both cases). Practices located in high socioeconomic areas had higher ILI consultation rates (4.3 vs 2.5 per 1000 consultations, p<0.05), antibiotic (30.7% vs 23.4%, p<0.05) and antiviral (34.2% vs 13.5%, p<0.05) prescribing than those in lower socioeconomic areas. The coexistence of chronic or mental health conditions was associated with lower ILI consultation rates, higher antibiotic use, but not with antiviral prescribing. However, those with chronic respiratory conditions had a higher frequency of antibiotic and antiviral prescribing in 2017 than individuals with other comorbidities. Although the apparent decline in antibiotic prescribing for ILI is welcome, the increase in antiviral use may not be targeting those at high risk of complications from infection. © Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.