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Background The WHO has recognised medication-related harm as a key area for improvement, launching to reduce preventable adverse drug reactions (ADRs) and adverse drug events (ADEs). The International Group for Reducing Inappropriate Medication Use & Polypharmacy recommends identifying subgroups that will most benefit and those that may not. While specific drug classes are linked to ADRs and ADEs, further research is needed to explore socioeconomic differences. The objective was to investigate if socioeconomic status (SES) is associated with the prescribing of high-risk drug classes in older community-based populations.Methods We used linked data from a national pharmacy claims database, the Health Service Executive-Primary Care Reimbursement Service (HSE-PCRS) General Medical Services (GMS) scheme, and wave 5 (2018) of The Irish LongituDinal study on Ageing (TILDA). Educational level, household income, and private health insurance were analysed in relation to antithrombotic agents, beta-blocking agents, calcium channel blockers, diuretics, renin-angiotensin-aldosterone system, psychoanaleptics, NSAIDs and polypharmacy. For drug classes, we used binary logistic regressions, and for polypharmacy ordinal logistic regressions. All analyses were made with robust standard errors and as unadjusted and adjusted. Missing data in household income was handled using multiple imputation.Results The study population contained 2,482 individuals (46% males and median age of 76 (IQR:72–80)). Median number of conditions was 2 (IQR:1–3) and 577 (23%) had ≥10 drug classes. Individuals with lower education levels, household income below the national median, and no health insurance were more likely to be prescribed all included high-risk drug classes and experience polypharmacy compared to those with higher education, household income above median and with private health insurance. Psychoanaleptics were the highest-risk drug class prescribed to those with lower socioeconomic status: (adj. OR 3.87 [95%CI:2.63;5.69]) for primary education vs third/higher education, (adj. OR 2.25 [95%CI:1.74;3.46]) for low vs. high income, and (adj. OR 3.53 [95%CI:2.67;4.67]) for health insurance versus none.Conclusion A strong association was found between SES and high-risk drug classes and polypharmacy. Individuals with low education, income, and without private health insurance, were at greater risk for using drugs associated with ADRs and ADEs and polypharmacy. The findings highlight the need for interventions to reduce health disparities related to medication use, including better access to healthcare, medication reviews, and improved health literacy for those of low SES.