Express Scripts Formulary 2026: National Preferred Drug List and Exclusions

Key Facts

How the Express Scripts National Preferred Formulary is organised

The Express Scripts National Preferred Formulary sorts entries by drug name, not by cost tier. In the 2026 edition published by Evernorth Health Services, brand-name drugs are printed in capital letters and generic drugs in lower case, and three markers qualify an entry: [INJ] for an injectable drug, [OTC] for an over-the-counter product, and [SP] for a specialty drug. Those markers describe what the drug is, not what it costs. The published list itself (Express Scripts, 2026 National Preferred Formulary, document PRMT94F9ANP-26) states it is an abbreviated version of the full formulary and is "not all-inclusive".

What it means when a drug is excluded from the Express Scripts formulary

An excluded drug is one the Express Scripts National Preferred Formulary does not cover, and Express Scripts publishes those exclusions in a separate document rather than in the drug list itself. The 2026 formulary directs readers to express-scripts.com/2026drugs for the full exclusion list together with the covered alternative for each entry, and states that costs for covered alternatives may vary. Exclusion is not the same as unavailability: an excluded drug can still be dispensed and paid for out of pocket, and some plans cover it through an exception process.

Why a brand-name drug can leave the formulary during the plan year

A brand-name drug can move to nonformulary status mid-year when a generic version becomes available, and the 2026 Express Scripts National Preferred Formulary says so on its first page. Generic equivalence in the United States is determined by the Food and Drug Administration, which publishes therapeutic equivalence ratings in the FDA Orange Book. That is why the formulary document carries the line "THIS LIST IS SUBJECT TO CHANGE" alongside its effective dates of 1 January 2026 through 31 December 2026, and why a list downloaded in January may not match the list in force in October.

How Medicare Part D formularies differ from a commercial formulary

Medicare Part D formularies are regulated and a commercial formulary such as the Express Scripts National Preferred Formulary is not. The Centers for Medicare & Medicaid Services sets requirements for what a Part D plan's formulary must include and how it may change during a year, published under CMS prescription drug coverage contracting. A commercial employer plan using Express Scripts is governed by the plan sponsor's contract instead, which is why two members of two different employers can both be "on Express Scripts" and hold different drug lists for the same calendar year.

How to challenge a coverage decision on an Express Scripts plan

A coverage denial under an Express Scripts plan is appealable, and the route depends on whether the plan is Medicare or commercial. For Medicare drug plans, the Centers for Medicare & Medicaid Services publishes the appeals and grievances process, including coverage determinations and exceptions, at CMS prescription drug appeals, and Medicare.gov drug coverage (Part D) describes what a Part D plan must offer. For a commercial employer plan, the plan sponsor's own documents set the appeal path, and the Express Scripts formulary itself states that not all listed drugs are covered by every prescription plan. A prescriber's supporting statement is normally the first step in either case.

What "generic equivalent" means on a formulary

A generic equivalent is a drug the Food and Drug Administration has determined to be therapeutically equivalent to a brand-name product, not merely similar. The FDA explains the standard in FDA generic drug facts and publishes equivalence ratings in the Orange Book. That distinction is what makes the Express Scripts rule operative: the 2026 National Preferred Formulary states a brand-name drug may move to nonformulary status once a generic version becomes available, so an FDA equivalence rating can change a member's coverage without the plan itself changing.

What to check when a prescription is not on the Express Scripts list

A drug missing from the published Express Scripts National Preferred Formulary has not necessarily been denied. The formulary document states that not all listed drugs are covered by every plan and that some drugs require preauthorization or step therapy or carry quantity limits, so coverage is decided by the specific plan rather than by the list. Express Scripts directs members to log in at express-scripts.com or to use its mobile app to see coverage and cost share for their own plan, and the exclusions document names a covered alternative where one exists. Plan documents govern, and a prescriber can request an exception where a plan offers one.

Sources and standards behind this page

Drug coverage in the United States is governed by published rules rather than by any one insurer's summary, and the sources below are the primary ones. They are linked so a reader can check a claim without taking this page's word for it.

• FDA Orange Book publishes the therapeutic-equivalence ratings that decide whether a generic may be substituted for a brand-name drug.
• FDA generic drug facts sets out what "generic equivalent" means and what a manufacturer must prove.
• CMS prescription drug coverage defines the rules a Medicare drug plan formulary must follow and how it may change mid-year.
• Medicare.gov drug coverage (Part D) states what a Part D plan is required to offer a member.
• CMS prescription drug appeals documents the coverage-determination and exception process when a drug is denied.
• Medicare Plan Compare is the official tool for checking what a specific plan charges for a specific drug at a specific pharmacy.
• Drugs@FDA is the federal database of approved drug products, which establishes whether a covered product exists and in what form.
• DailyMed carries the current FDA labeling for every marketed drug product, including approved strengths and forms.
• MedlinePlus drug information is the National Library of Medicine's consumer reference for what a medication is and how it is used.
• FTC report on pharmacy benefit managers documents how the middlemen between an insurer and a pharmacy shape what a plan actually covers.
• National Library of Medicine maintains the drug and health databases the sources above draw on.

This page describes how coverage and formularies work. It is not medical advice, and a reader's own plan documents and prescriber decide what applies to them.