OBJECTIVES: To estimate the 5-year projected impact on the annual pharmacy budget for allergic rhinitis (AR) patients in Mexico  METHODS: Mexican prevalence and treatment data for AR patients were obtained from published and nonpublished sources. The model considered 2 scenarios—without (pre) and with (post) FFNS. Market share data for corticosteroid treatment options for AR pre- FFNS and in the first year post-FFNS were obtained from nonpublished, real-world drug utilization data collected by GSK. Market shares for the second until fifth years post- FFNS were forecasted by the study authors. Drug costs were based on the Mexican Social Security Institute (IMSS). Wholesale Acquisition Cost was accessed on March 2010. The results for each indication were analyzed individually and summed to reflect the total impact of FFNS. Results were also considered on a per member per month (PMPM) basis to examine the relative impact on the plan. Sensitivity analyses were performed by varying several model input parameters  RESULTS: The estimated prevalence of AR in 2010 was 10%. In the year after its introduction, 60% of the AR population filled a prescription for FFNS. The estimated total cost for AR treatment prior to introduction of FFNS was $ 552 million and (532 to $ 384 million post FFNS. The incremental decrease in pharmacy benefit cost was ($ 20 to $ 84 millions) in 2010 dollars. These reductions translated to a medical care cost saving of $ 266 millions over 5 years.  CONCLUSIONS: Model results suggest that increasing the use of fluticasone furoate decreases total budget costs due to decreased acquisition drug costs.