OBJECTIVES:  To develop a flexible and generic economic model quantifying potential savings associated with Rx-to-OTC switches from the perspective of European policy makers and health care budget holders. METHODS: A systematic review of the literature of Rx-to-OTC switches was performed to understand the populations involved, key drivers of economic benefits and the factors impacting these.  To ensure applicability across Europe, health care settings were analysed for the UK, France, Germany, Italy, Spain and Poland.  Experts were consulted to validate the model structure and assumptions. RESULTS: A budget impact framework was used and the model was developed primarily for acute conditions.  The model considers six patient groups which may initiate the switched-to-OTC drug: those on the Rx drug, other Rx drugs, OTC-treated, untreated, and undiagnosed (OTC-treated and untreated).  From the budget holder perspective, the model includes savings due to avoided: Rx drug acquisition, doctor’s visits to obtain a prescription and emergency room visits or hospitalisations due to easier access to an effective or safer therapy.  The policy-maker perspective also includes employers’ benefits, such as less time-off work to obtain a prescription and less absenteeism & presenteeism due to easier access to therapies that improve employee productivity.  The algorithm to estimate cost consequences of potential adverse events due to lack of doctor’s supervision was developed.  The model has a 5-year time horizon with a function to conduct an analysis for one year which may represent the savings at the forecast peak uptake.  An option to estimate the consequences of the disreimbursement policies was incorporated.  The model is particularly sensitive to uptake rates across different groups of patients.  The model is flexible and easily adaptable to different acute conditions and countries in Europe. CONCLUSIONS: The economic impact associated with Rx-to-OTC switches can be credibly estimated in Europe.  Preliminary analyses suggest that such switches are cost-saving.