Medicare Part B usually covers drugs you wouldn't give yourself, like injections and infusions you get at a doctor's office or in a hospital outpatient setting. In most cases, after the Part B deductible ($283 in 2026), you pay up to 20% of the Medicare-approved amount for the drug. Your coinsurance may be lower for certain drugs whose prices have risen faster than inflation, and providers must accept assignment for Part B-covered drugs, so they shouldn't ask you to pay more than your coinsurance for the drug itself.
Which drugs does Part B cover?
Medicare.gov says Part B usually covers drugs you wouldn't typically give to yourself. Examples include:
- Injectable and infused drugs given by a licensed medical provider, which covers most of them.
- Drugs used with Part B-covered durable medical equipment, like an infusion pump, when medically necessary.
- Immunosuppressive drugs after a Medicare-covered transplant.
- Some drugs for End-Stage Renal Disease (ESRD), like erythropoiesis-stimulating agents for anemia.
Drugs you pick up at the pharmacy and take yourself are usually covered by Part D, your drug plan.
What do I pay for Part B drugs?
Medicare.gov says that in most cases, after you meet the Part B deductible, you pay up to 20% of the Medicare-approved amount for Part B drugs. The Centers for Medicare & Medicaid Services (CMS) set the 2026 deductible at $283.
Medigap may cover some or all of your coinsurance. Medicare Advantage plans cover Part B drugs too, but they may use different cost sharing and require prior authorization.
Why does my coinsurance change from time to time?
Medicare.gov says you might pay lower coinsurance for certain Part B drugs if their prices have gone up faster than the rate of inflation. It also notes that your coinsurance amount can sometimes change depending on the drug's price.
So if you get the same infusion regularly, the amount you owe may change from one period to the next. That's not always an error. Check your Medicare Summary Notice for the approved amount each time.
What else might be on the bill?
An infusion visit can include several charges:
- The drug itself. Your share is up to 20%.
- The administration. The service of giving you the injection or infusion is a separate Part B service, usually with its own 20% coinsurance.
- An office visit, if the doctor also examined you.
- Hospital outpatient charges, if you got it at a hospital clinic. Medicare.gov says if Part B drugs you get in a hospital outpatient setting are part of your outpatient services, you pay a copayment for the services.
Medicare.gov also says if you get a drug that isn't covered in a hospital outpatient setting, you pay all costs for it unless you have other drug coverage. This sometimes happens with drugs you'd normally take yourself, given during an outpatient or observation stay.
How do I check a Part B drug bill?
- Find each line on your MSN. Look for the drug and the administration as separate items.
- Compare the amount you owe with the "maximum you may be billed."
- Check the number of units. Drug bills list units, and an extra unit can mean a big difference. Ask the office to confirm the dose.
- Check that Medigap paid its share.
- Ask about assignment. Medicare.gov says providers must accept assignment for Part B-covered drugs, so you shouldn't be asked to pay more than your coinsurance for the drug.