Preventive drug lists and formularies: Understanding the difference
August 04, 2026Some high-deductible health plans include a preventive drug benefit. This benefit may allow members to pay a copay for certain preventive drugs before they meet their deductibles. But the drug must appear on the preventive drug list that matches the plan’s formulary.
For example, two employees are enrolled in high-deductible health plans that include a preventive drug benefit. One picks up a blood pressure medicine and pays a copay, even though they have not met their deductible. The other takes a different blood pressure drug and must meet the deductible first.
That can be hard to explain. The difference often comes down to the plan’s formulary and preventive drug list. The two lists work together, but they do different jobs.
Which drugs count as preventive?
Preventive drugs help stop a health problem from starting or getting worse. Some help control risks before they lead to more serious care. Common examples include certain drugs for blood pressure, cholesterol and diabetes.
A drug does not get preventive coverage just because it treats a potential health problem. The drug must appear on the preventive drug list for the member’s plan.
One plan, two different lists
A formulary lists all prescription drugs that a plan covers. It also shows the tier for each drug. The formulary may set other coverage rules:
- Prior authorization means the drug needs approval before the plan covers it
- Step therapy means a member must try another drug first
- Quantity limits set how much of a drug the plan covers at one time
The preventive drug list is smaller. It includes drugs from the formulary that qualify for the plan’s preventive drug benefit. Depending on the plan, the list may include drugs from more than one tier.
For 3-Tier Open and the Preferred Value Formulary, Excellus BlueCross BlueShield’s clinical strategy team manages the drug lists. The Pharmacy & Therapeutics Committee approves them. Express Scripts® manages the National Preferred Formulary lists for eligible self-funded groups. The teams update their lists each year.
Why the matching list matters
Preventive drug lists differ by formulary. A drug on the 3-Tier Open preventive list may not appear on the National Preferred Formulary list. Or the two lists may cover it in different ways.
Not every high-deductible health plan includes preventive drug coverage. When a plan does include this benefit, a member may pay only a copay for a qualifying preventive drug before meeting the deductible. The copay counts toward the member’s out-of-pocket maximum. It does not count toward the deductible.
A drug that is not on the preventive list follows the plan’s standard pharmacy benefit. The member may need to meet the deductible first.
Using a list that does not match the plan can lead to a surprise at the pharmacy counter.
A closer look at 3-Tier Open, PVF and NPF
Commercial plans may use different formularies. Each one offers a different mix of drug choice and cost savings.
3-Tier Open offers the broadest range of coverage of prescription drugs. When a lower-cost option exists, a higher-cost drug may stay on the formulary but move to a higher tier. Members still have access, but they may pay more for a non-preferred drug.
The Preferred Value Formulary, or PVF, focuses more on value. Excellus BCBS reviews drugs for safety, how well they work and cost. PVF may not cover a higher-cost drug when a lower-cost option offers similar results. A member may need to change drugs or ask for an exception.
The National Preferred Formulary, or NPF, is managed by Express Scripts and includes most generic drugs and some brand and biosimilar drugs. NPF may leave out a drug when a more cost-effective option exists. This can offer savings, but it can also lead to more drug changes for members.
What members may pay
Suppose a member has a high-deductible health plan with preventive drug coverage and takes a cholesterol drug on the preventive drug list for their plan. The member may pay the drug’s copay before meeting the deductible. That payment counts toward the out-of-pocket maximum.
Now suppose the formulary covers a different cholesterol drug, but the preventive list does not include it. The member may need to meet the deductible before the plan begins to share the cost.
Preventive status does not remove other coverage rules. Prior authorization, step therapy and quantity limits may still apply.
Check the list before questions become surprises
Do not wait for an employee to question a pharmacy bill. Check the preventive drug list during plan selection and renewal. Use it when you compare plan options or explain benefits to employees. It can also help when a member starts a new drug or asks why their cost changed.
Always match the list to the member’s formulary and plan year.
Where members can find their list
Members can log in to their Excellus BCBS account. Then they can go to:
Prescriptions > Manage Medications > Preventive Drug List
The lists change each year. Members should use the current list for their plan.
Knowing the difference between these lists helps explain benefits more clearly and compare plans with more confidence. Before you answer a member’s question or compare plan options, confirm the plan’s formulary and the preventive drug list that matches it. That one check can prevent surprises at enrollment, renewal and the pharmacy counter.
Help employees understand their coverage
Share the preventive drug flyer with employees for more information about preventive drug coverage.
Express Scripts is an independent company providing pharmacy services.