Increasing prescription drug costs are a major concern in health care. The literature lacks an up-to-date assessment of US expenditures on topical steroids, one of the most prescribed medications in dermatology.

To characterize trends in Medicare spending and costs per unit of topical steroids and to model potential savings from substitution of the cheapest steroid within each potency class.

This is a retrospective analysis of Medicare Part D Public Use Files, which provides prescription drug expenditure data between 2012 and 2021.

Between 2012 and 2021, Medicare Part D spent $5.7 billion on topical steroids, with generics accounting for 98.3%. While there has been a steady decline since 2015, total annual spending has overall increased by 35.6%, from $322.2 million in 2012 to $437 million in 2021. Inflation-adjusted costs per unit increased for most generic topical steroids, while the rate of change declined with increasing market competition. Medicare had potential savings of $2.4 billion if prescriptions were substituted for the cheapest steroid within each potency class.

The data set represented only 70% to 77% of beneficiaries with Part D plans, excluded manufacturer rebates, and aggregated all drug strengths. We also excluded drugs with proprietary vehicles.

Medicare expenditures on topical steroids have increased in the past decade, primarily driven by rising generic drug costs.