Introduction: Age limits for diagnostics and treatments have been largely removed and replaced by an active diagnostic and treatment practice among the oldest old and has led to concerns about potential overtreatment during the last years of life. Methods: Use of prescription medication in the last years of life was assessed from 1995 to 2012 for the entire 1905 and 1915 Danish birth cohorts using nationwide register data. Medication use was quantified as the number different pharmacy-redeemed drugs during 120 days up to a given date. Results: For both cohorts, prescription medication use increased with proximity to death and calendar year, while age at death had little impact; use in the 1915 cohort was markedly higher than in the 1905 cohort. Average number of prescription medications varied from below 3 to above 9 depending on age, calendar year and proximity to death. From 1995 to 2005, average number of prescription medications for a 90-year-old person in the last month of life increased from 6.0 to 8.7. Out of 90-year-old persons dying in 2005, 82% were exposed to polypharmacy, up from 63% in 1995. Conclusions: Prescription medication use accelerates throughout the last of years life among two Danish oldest old cohorts born 10 years apart, with substantially larger use in the most recent cohort. This pattern suggests an increase in drug prescribing regimens in the period 1995–2012, reinforcing the need for evidence-based guidelines on medications in the particularly vulnerable population of the oldest old patients in their last years of life.