Part B does not cover most prescription drugs — that is what Part D is for

Part B covers some injectable medications and drugs you receive during a hospital or doctor visit, but it does not cover prescriptions you pick up at a pharmacy. If you need regular medications from a drugstore, you need Part D (prescription drug coverage) or another plan that includes pharmacy benefits.

Part B does cover specific drugs given to you in a clinical setting — for example, chemotherapy at an oncology center, certain biologics injected during a rheumatology appointment, or vaccines given at your doctor's office. It also covers some drugs you self-inject at home if they are medically necessary and cannot be taken orally. But the moment you walk into a pharmacy with a prescription slip, Part B stops covering it.

This distinction matters because many people assume Medicare covers all medications once they turn 65. It does not. You have to take a separate step to add Part D coverage, or you will pay the full price out of pocket.

Key Takeaways

  • Part B covers injectable drugs given in a doctor's office or hospital, vaccines, and some self-injected biologics, but not pharmacy prescriptions.
  • Part D is the Medicare program that covers medications you pick up at a pharmacy or have delivered to your home.
  • If you do not sign up for Part D when you first become may be able to access, you may pay a permanent penalty on your premiums later.
  • You can add Part D to Original Medicare, or choose a Medicare Advantage plan that includes prescription coverage.

What Part B actually covers: drugs given in a medical setting

Part B covers drugs that are part of a medical service you receive from a doctor, hospital, or outpatient clinic. This includes chemotherapy, immunotherapy, certain biologics for rheumatoid arthritis or other conditions, and intravenous medications. It also covers vaccines — flu shots, pneumonia vaccines, shingles vaccines — when administered by a healthcare provider.

If your doctor injects or infuses a medication as part of your treatment, Part B typically pays for the drug itself (after you meet your deductible and coinsurance). You pay 20 percent coinsurance for most Part B services, and Part B covers 80 percent.

Some self-injected drugs are also covered under Part B if they meet specific criteria: they must be medically necessary, they cannot be taken by mouth, and they must be given under medical supervision or ordered by a doctor. Examples include certain biologics for autoimmune conditions or growth hormone. But this is narrower than it sounds — most self-injected medications are not covered by Part B.

Why pharmacy prescriptions need Part D, not Part B

Part B was designed to cover doctor visits, hospital care, and treatments given in a medical setting. Prescription drugs picked up at a pharmacy fall outside that scope. Congress created Part D as a separate benefit specifically for pharmacy medications because the costs and the way people use them are different from in-office treatments.

Part D is optional, but if you do not sign up when you first become may be able to access for Medicare, you will pay a late enrollment penalty on your Part D premiums for as long as you have Medicare. The penalty is roughly 1 percent of the national average Part D premium for each month you went without coverage. If you delay for two years, the penalty compounds and stays with you permanently.

The only exception is if you have other creditable coverage — meaning a health plan from a current or former employer, a union, TRICARE, or the Veterans Health Administration that covers prescriptions at least as well as Part D does. If you have that, you can delay Part D without penalty.

How to add Part D or get prescription coverage

You have two main routes: add Part D to Original Medicare, or choose a Medicare Advantage plan that includes prescription coverage.

If you have Original Medicare (Part A and Part B), you can enroll in a standalone Part D plan during the annual enrollment period (October 15 to December 7 each year) or during your initial enrollment period when you first turn 65. You choose from plans offered by insurance companies in your area, and the coverage and cost vary by plan and by pharmacy. You can compare plans on Medicare.gov.

If you choose a Medicare Advantage plan instead of Original Medicare, most of them include prescription drug coverage built in. You do not buy Part D separately — the plan covers both medical services and prescriptions. Medicare Advantage plans vary widely in which drugs they cover and what you pay, so read the formulary (the list of covered drugs) before you enroll.

What you pay for prescriptions under Part D

Part D plans have a standard structure: you pay a monthly premium, an annual deductible (which varies by plan), and then copayments or coinsurance for each prescription. The amount you pay depends on which tier the drug is on — generic drugs are usually cheaper than brand-name drugs, and specialty drugs are often the most expensive.

There is also a coverage gap called the "donut hole." Once you and your plan have spent a certain amount on prescriptions in a year, you enter the gap and pay a higher percentage of the cost until you reach a catastrophic coverage threshold. After that, you pay a small copayment and Medicare covers the rest. The exact amounts change each year.

If your income is low, you may may have access to for Extra Help, a program that reduces your Part D premiums, deductibles, and copayments. You can learn more about Extra Help on Medicare.gov or by calling 1-800-MEDICARE.

Drugs Part B covers in a hospital or outpatient setting

Part B covers the cost of drugs that are part of a covered service. If you are admitted to the hospital, Part B does not pay for your hospital stay (that is Part A), but it does cover certain drugs given to you while you are there. If you receive chemotherapy or dialysis at an outpatient center, Part B covers the drugs used in that treatment.

Part B also covers some drugs you receive during an emergency room visit or urgent care visit, as long as they are part of the treatment for the condition you came in for. The key is that the drug is given to you by a healthcare provider as part of a medical service, not dispensed to you to take home.

What happens if you do not have Part D coverage

If you do not have Part D or another prescription drug plan, you pay the full price of medications at the pharmacy. There is no Medicare coverage to help. Many people in this situation use discount programs, generic alternatives, or patient information programs from drug manufacturers, but these are not Medicare benefits — they are separate programs.

If you realize later that you need Part D, you can enroll during the annual enrollment period or if you have a may have access to life event (such as losing other coverage). But if you wait more than 63 days after losing creditable coverage, you will owe the late enrollment penalty for the rest of your time on Medicare.

Frequently Asked Questions

Does Medicare Part B cover insulin?

If you pick up insulin at a pharmacy, Part B does not cover it — you need Part D. But if you receive insulin as part of treatment in a hospital or doctor's office, Part B covers it. Most people with diabetes use Part D to cover their insulin prescriptions.

Are blood pressure or cholesterol medications covered by Part B?

No. These are taken at home and picked up at a pharmacy, so they require Part D coverage. Part B only covers drugs given to you in a medical setting by a healthcare provider.

What if I have a Medicare Advantage plan — do I still need Part D?

Most Medicare Advantage plans include prescription drug coverage, so you do not need a separate Part D plan. But check the plan's formulary before you enroll to make sure your medications are covered. Some Medicare Advantage plans do not include drug coverage, and if yours does not, you can add a standalone Part D plan.

Can I switch Part D plans if my medications are not covered?

Yes. You can change Part D plans during the annual enrollment period each fall, or if you have a may have access to life event such as moving to a new state or losing other coverage. You can also request an exception from your current plan if a drug is not covered but your doctor says it is medically necessary.

What is the difference between Part B coinsurance and Part D copayments?

Part B typically charges 20 percent coinsurance — you pay 20 percent of the approved cost after you meet your deductible. Part D charges copayments (a flat dollar amount per prescription) or coinsurance (a percentage), depending on the plan and the drug tier. The structure is different because Part B covers services and Part D covers drugs.