Background: Opioid use has more than doubled over recent decades, and Denmark occupies fifth place in the global ranking. These increases have been partly attributed to the ageing population. Objective: Our objective was to assess the impact of age over time on utilisation of the most commonly used opioids in Denmark. Methods: We retrieved nationwide sales data on opioid sales in Denmark from 1999 to 2017. We investigated utilisation trends in age groups for the four opioids with the highest use. We used three volume-based metrics (defined daily doses/1000/day, oral morphine equivalents/1000/day, and packages dispensed/year) and one person-based metric (users/1000/year). Results: The four opioids selected according to users/1000/year were tramadol (46.1), codeine and combination products (12.4 for codeine, 3.7 for codeine and acetylsalicylic acid, and 4.2 for codeine and paracetamol), morphine (17.0), and oxycodone (12.1). Overall utilisation according to volume and person metrics increased for all except codeine and combination products. Tramadol doses or strength increased, albeit less with increasing age. Oxycodone doses or strength decreased for all age groups but were nearly unchanged for the age group ≥ 80 years. Conclusion: Tramadol is the most utilised opioid in Denmark and was prescribed at increasing doses or strengths over the study period, particularly in the younger (< 80 years) age groups. Overall, oxycodone was prescribed at decreasing doses or strengths over time but remained unchanged for the age group ≥ 80 years. There is a need to address the pharmacological treatment of pain in terms of age, with tramadol and oxycodone being possible targets for regulatory efforts.