We find that GMS drug costs depend on age-but not gender-on income, health status, community drug scheme coverage rates, and they are significantly lower for all age cohorts in Donegal and the North West region. The GMS drug costs of high income cohorts tend to increase as their health status improves, whereas they tend to decrease as the health status of low income cohorts improves. A uniform 1% gain in health status has little impact on total GMS prescribing costs. Similarly, if the health status of all Irish regions improved to match that of the East region in 2010 it would only have reduced public prescription costs by around 32 € million of the 1.8 € billion GMS drugs bill. We find that giving free prescription drugs to all persons aged 'under 5' in 2010 would have only a minor impact on 2010 GMS drug costs, whereas giving universal GMS coverage to all persons would have doubled public prescription costs from 1.8 € billion to circa 3.6 € billion.