What Drugs Does Medicare Part B Cover? (2026)

If you're trying to figure out whether Medicare Part B will cover a prescription, the answer comes down to one rule: Part B mostly pays for drugs you wouldn't usually give yourself. Think of the ones injected or infused at a doctor's office. Most prescriptions you take at home run through Part D instead. Sort out which side your drug falls on and you'll know which part pays, and roughly what it'll cost you.

In This Guide

• Key Takeaways
• Which Drugs Does Medicare Part B Cover?
• Part B vs. Part D: Which One Pays for Your Drug?
• What You'll Pay for Part B Drugs
• The Vaccines Part B Covers at No Cost
• How to Tell Which Medicare Part Covers Your Drug: Part B or D
• Frequently Asked Questions
• Learn More

Which Drugs Does Medicare Part B Cover?

Part B is the medical-insurance side of Medicare, and it covers only a limited set of prescription drugs. As medicare.gov puts it, Part B "covers drugs you wouldn't typically give to yourself, like those you get at a doctor's office or in a hospital outpatient setting."1 That's the whole idea in one sentence: if a nurse or a machine has to deliver it, it tends to be a Part B drug.

Here's the kind of thing that falls under Part B:1

• Most injectable and infused drugs, when a licensed medical provider gives them, such as in a doctor's office or hospital outpatient department
• Certain drugs infused through Part B-covered durable medical equipment, like an infusion pump, when the drug is medically necessary
• Monoclonal antibodies for treating early Alzheimer's disease
• Some oral cancer drugs, when the same drug also comes in an injectable form or is a prodrug of one, and oral anti-nausea drugs taken around chemotherapy
• Injectable osteoporosis drugs
• Injectable blood clotting factors for hemophilia, whether you give them to yourself or get them in a doctor's office
• Erythropoietin by injection, if you have End-Stage Renal Disease (ESRD) or need it to treat anemia related to certain other conditions
• Immunosuppressive drugs after an organ transplant Medicare helped pay for, as long as you meet the Part A and Part B conditions in the FAQ below

Notice the pattern. Most of these are drugs someone administers to you, or drugs tied to a specific covered treatment like a transplant or chemotherapy.1 That's not an accident, and it's the key to the next question.

Part B vs. Part D: Which One Pays for Your Drug?

This is where most of the confusion lives, so let's make the rule plain. Medicare drug coverage is split between two parts, and the dividing line is whether you'd normally take the drug yourself.

By regulation, Part B generally won't pay for a drug that's usually self-administered by the patient. The rule sits in the Code of Federal Regulations at 42 CFR 410.29, which excludes "any drug or biological which is usually self-administered by the patient."1 So the pills you pick up at the pharmacy and take at your kitchen table? Those are exactly the drugs Part B steps back from.

That's why you also have Part D. Most prescription drugs you take at home are covered under Part D instead, either through a standalone Medicare drug plan or through a Medicare Advantage plan, since most Medicare Advantage plans include Part D drug coverage.1,3 The short version: office-administered leans Part B, take-it-at-home leans Part D.

What You'll Pay for Part B Drugs

Part B drugs aren't free, and they don't work like a flat pharmacy copay. In most cases, after you meet the annual Part B deductible ($283 in 2026), you pay up to 20% of the Medicare-approved amount for the drug, and that coinsurance amount can sometimes change depending on the drug's price.1,2

Two situations can change that math:

• Lower coinsurance on some drugs: if the price of a Part B drug or biological has climbed faster than inflation, you might owe a lower coinsurance on it, whether you get it at a doctor's office, a pharmacy, or another outpatient setting. Which drugs qualify, and how much you'd save, changes every quarter.1
• Hospital outpatient drugs: when the drug is part of your hospital outpatient services, you'll pay a copayment for those services. If a hospital outpatient department gives you a drug that Medicare doesn't cover in that setting, you pay the drug's full cost unless you have other drug coverage.1

Because coinsurance is a percentage, not a fixed dollar amount, the more expensive the drug, the more your share is. Original Medicare puts no yearly limit on what you pay out of pocket unless you have supplemental coverage, like a Medicare Supplement (Medigap) policy, or you join a Medicare Advantage plan. On a costly infused drug, like an Alzheimer's antibody or a chemotherapy infusion, that can add up fast.1

One protection is worth knowing. Doctors, other health care providers, and pharmacies must accept assignment for Part B-covered drugs, so they should never ask you to pay more than the coinsurance or copayment for the drug itself.1

The Vaccines Part B Covers at No Cost

Not every Part B drug comes with coinsurance. Medicare Part B covers the COVID-19, flu, pneumococcal, and hepatitis B vaccines at $0 with no deductible, as long as your provider accepts assignment.1 If a doctor's office or pharmacy tries to bill you for one of those, that's worth a question, because for these four, Part B is designed to leave you with nothing to pay. Other adult vaccines the Advisory Committee on Immunization Practices (ACIP) recommends, including the shingles and RSV vaccines, generally run through Part D instead, and your drug plan won't charge a copayment or deductible for them.1

How to Tell Which Medicare Part Covers Your Drug: Part B or D

When you're staring at a prescription or a bill and can't tell which part applies, walk through it like this:

1. Ask who administers it. If a clinician injects or infuses it, or a covered pump delivers it, you're likely in Part B territory.
2. Ask where you get it. A drug given in a doctor's office or hospital outpatient department points to Part B. A drug you fill at a retail pharmacy and take at home points to Part D.
3. Check the special categories. Some oral cancer drugs, oral anti-nausea drugs, injectable osteoporosis drugs, hemophilia clotting factors, and post-transplant immunosuppressants have their own Part B rules, so don't assume "it's a pill, so it's Part D."1
4. When in doubt, ask before you fill. Your prescriber's office or your plan can tell you which part pays, and a quick call can save you from a surprise bill or a pharmacy denial.

Getting this right matters because the wrong assumption costs real money. Someone who expects a flat Part D copay and instead owes coinsurance of up to 20% on an infused drug can be caught off guard, and someone told "Part B doesn't cover drugs" might skip coverage they were actually entitled to.1

Learn More

Find personalized help sorting out whether Part B or Part D covers your prescription at brevy.com.

The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.