A survey conducted by the National Consumer Agency suggests that some pharmacies are charging double the price of other pharmacies for some drugs.
It shows huge differences in the cost of individual prescription medicines in local areas.
The nationwide survey of pharmacies found huge variations in the prices charged to private customers for 39 common prescription medicines.
The percentage differences in prices of individual prescription medicines ranged from 37% to 199%.
The largest price variation for an individual product within a local area was for a drug commonly used to treat stomach ulcers.
Prices ranged from €22 to €49 for the drug in pharmacies in Co Waterford.
In Dublin, across the 39 products surveyed, the minimum price difference for any individual product was 34%.
The National Consumer Agency is now urging customers to compare the costs of prescription medicines in their local area before choosing a pharmacy.