Many people are confused about which part of Medicare will cover their drugs. To answer this question, follow these general rules of thumb:
Part A will continue to cover the drugs you need during a Medicare-covered stay in a hospital or skilled nursing facility. Note: If you are getting skilled nursing care that is not covered by the Part A benefit, your drugs may be covered by the Medicare drug benefit (Part D) (if you are enrolled in a Medicare private drug plan).
Part B will continue to cover drugs administered by your doctor or at a dialysis facility, but the doctor or facility has to buy the drugs themselves. Part B also covers a limited number of outpatient prescription drugs, mainly certain oral cancer drugs (chemotherapy). Outpatient drugs previously paid for by Part B will continue to be paid for by Part B. Part D (see below) cannot pay for any drugs that are covered by Part B.
Part D covers outpatient drugs through Medicare private drug plans. If you join a Medicare private drug plan (Part D), it should cover most of the prescriptions your doctor writes for you to fill at the drug store. Check to see if your Medicare private drug plan includes the drugs you need on its list of covered drugs (formulary).
While some drugs are covered only by Part B, there are a few drugs that can be covered by either Part B or Part D depending on the circumstances.