Last reviewed June 2026

What is a specialty drug, and why is it so expensive?

Short answer: Specialty drugs are high-cost medications for complex or chronic conditions (like cancer, autoimmune disease, or MS) that often need special handling or administration. They carry the highest formulary tier and are a leading driver of plan costs.

Specialty drugs treat complex, chronic, or rare conditions and are frequently biologics that are expensive to develop, manufacture, and store; many require refrigeration, injection, or clinical oversight. Plans place them on the top formulary tier with the highest cost-sharing (often coinsurance rather than a flat copay) and may require prior authorization or step therapy. Because a small number of patients on specialty drugs can account for a large share of total drug spend, they’re a major focus of cost-control programs like PBM management and copay accumulators.

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