Background With age, the number of chronic conditions increases along with the use of medications. For several years, polypharmacy has been found to be on the increase in western societies. Polypharmacy is associated with an increased risk of adverse drug events (ADE). Medications called potentially inappropriate medications (PIM) have also been found to increase the risk of ADEs in an older population. In this study, which we conducted during a national information campaign to reduce PIM, we analysed the prevalence of PIM in an older adult population and in different strata of the variables age, gender, number of chronic conditions and polypharmacy and how that prevalence changed over time. Methods This is a registry-based repeated cross-sectional study including two cohorts. Individuals aged 75 or older listed at a primary care centre in Blekinge on the 31st March 2011 (cohort 1, 15,361 individuals) or on the 31st December 2013 (cohort 2, 15,945 individuals) were included in the respective cohorts. Using a chi2 test, the two cohorts were compared on the variables age, gender, number of chronic conditions and polypharmacy. Use of five or more medications at the same time was the definition for polypharmacy. Results Use of PIM decreased from 10.60 to 7.04% (p-value < 0.001) between 2011 and 2013, while prevalence of five to seven chronic conditions increased from 20.55 to 23.66% (p-value < 0.001). Use of PIM decreased in all strata of the variables age, gender number of chronic conditions and polypharmacy. Except for age 80-84 and males, where it increased, prevalence of polypharmacy was stable in all strata of the variables. Conclusions Use of potentially inappropriate medications had decreased in all variables between 2011 and 2013; this shows the possibility to reduce PIM with a focused effort. Polypharmacy does not increase significantly compared to the rest of the population.