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Medicare prescription drug coverage

There are two types of plans you can choose from that offer Medicare Part D coverage. They are prescription drug plans (PDPs) and Medicare Advantage prescription drug plans (MAPDs). Expand each question below to learn more about Medicare Part D coverage.

Medicare prescription drug coverage (Part D) is offered through private insurance companies, like Aetna®. You can get Part D coverage through either:


  • A stand-alone prescription drug plan (commonly referred to as a PDP)
  • A Medicare Advantage prescription drug plan (commonly referred to as a MAPD)

A prescription drug plan (PDP) is a stand-alone Medicare Part D plan. PDPs only offer Part D and work together with your Original Medicare. This is a good option for someone who wants to stay in Original Medicare but add prescription drug coverage.

You are eligible to enroll in a PDP if you are already enrolled in Medicare Part A and/or Medicare Part B. Medicare Part D Prescription Drug Plans are only available through private insurers such as Aetna®.


For more information, please visit our Unpacking Medicare prescription drug coverage page.

A Medicare Advantage prescription drug plan (or MAPD) is a plan that includes medical and prescription drug coverage.  It is offered from a private insurers such as Aetna®.


A MAPD plan includes:


  • Medicare Part A (hospital)
  • Medicare Part B (medical)
  • Medicare Part D (prescription)

Like other health plans, MAPDs come in various forms, such as HMOs (health maintenance organizations) and PPOs (preferred provider organizations).

There are four phases of Medicare Part D coverage you may enter in a plan year. What you pay for covered prescriptions may change as you move through the phases. Coverage phases do not affect monthly premium amounts.


  1. The annual deductible phase — You begin in the annual deductible phase (if your plan has a deductible). You pay the full cost of your covered prescriptions until you reach your deductible. Keep in mind, some prescriptions may not apply to the deductible.

  2. The initial coverage phase — This is the phase after you have met your deductible (if it applies) and before your total drug costs have reached the initial coverage limit. Total drug costs include what you and your plan have paid for covered prescription drugs.

  3. The coverage gap phase — The coverage gap is also called the “donut hole.” It begins after the total amount spent by you and your drug plan on covered prescription drugs reaches the initial coverage limit. In this phase, you’ll pay no more than 25% of the cost for covered brand-name or generic prescription drugs. This phase ends when you have spent enough to qualify for catastrophic coverage. Some people will never enter the coverage gap because their drug costs won’t be high enough.

  4. The catastrophic coverage phase — This is the drug coverage phase that happens after you get out of the coverage gap (donut hole). With catastrophic coverage, you pay a reduced amount for covered drugs for the rest of the year.
  • Each plan has a formulary showing which drugs it will cover, the tier a drug is on, any limits or requirements and mail-order availability.
  • Both generic and brand drugs are covered under Part D. Visit our formulary FAQ page to learn more.
  • A generic drug is a prescription drug that is approved by the Food and Drug Administration (FDA) as having the same active ingredient(s) as the brand-name drug. Generally, a “generic” drug works the same as a brand-name drug and usually costs less.
  • A brand-name drug is a prescription drug that is made and sold by the company that originally researched and developed the drug. A brand-name drug has the same active ingredients and formula as its generic version.


Here are some examples of what Part D prescription drug plans do not cover:


  • Drugs given in hospitals or doctors’ offices that are already covered under Part A or Part B
  • Any drugs not listed on a plan’s drug formulary (except in special circumstances)
  • Non-prescription drugs or prescription vitamins (other than prenatal vitamins). Other examples include weight loss or weight gain, hair growth and/or erectile dysfunction drugs.

ⓘ SilverScript® Plus (PDP) includes coverage for some excluded drugs not typically covered by a Medicare prescription drug plan. This includes some prescription vitamins and generic erectile dysfunction drugs.


For a more complete list of drugs not covered by Medicare, please visit our Prescription drug formulary FAQ page.

Aetna® Medicare Part D plans cover the shingles vaccine and some commercially available vaccines. Part D in general covers recommended adult immunizations when needed to prevent illness. Talk to your provider about which ones are right for you.

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