Specialty pharmaceuticals are a rapidly growing share of total drug expenditures by public and private health plans. These drugs, typically used to treat chronic, serious, or life-threatening conditions, such as cancer, rheumatoid arthritis, growth hormone deficiency, and multiple sclerosis, are often priced much higher than traditional drugs. Total costs can be in the thousands of dollars a month and can exceed $100,000 a year for some products. There are usually few if any low-cost generic equivalents.

These high costs represent an increasing burden on payers, including governments and employers. Because health plans often require substantial cost sharing for specialty drugs, there is also a large impact on patients who need such medicines. Some are concerned that cost sharing could discourage the use of these drugs, perhaps leading to adverse health outcomes.