Medicare Part B is the medical insurance component of Original Medicare, covering services and supplies necessary for diagnosing or treating a medical condition. Part B covers a limited set of outpatient prescription drugs and biologicals, generally defined by the method and setting of administration. This differs significantly from Medicare Part D, which is the primary source of coverage for most retail, self-administered prescription drugs.
The core principle for Part B drug coverage is that the medication must be administered by a healthcare professional as part of a covered medical service. This design means Part B often covers treatments that cannot be safely or effectively self-administered at home. Understanding the distinctions between Part B and Part D coverage is important.
Medications Administered by a Healthcare Professional
This category represents the largest portion of Part B drug coverage and includes medications that are typically injected or infused in an outpatient setting. These are generally drugs that require the oversight of a physician or other licensed professional due to their complexity or administration method. The coverage often falls under the legal definition of services furnished “incident to” a physician’s service.
A wide range of high-cost specialty drugs and biologicals fall into this group, often used to treat complex conditions like cancer, rheumatoid arthritis, macular degeneration, and immune deficiencies. For instance, many chemotherapy drugs administered intravenously are covered by Part B when given in a doctor’s office or hospital outpatient department. Biologics for conditions such as rheumatoid arthritis, like those given by IV infusion, are also covered under Part B.
Part B also covers other injectable treatments, such as certain drugs for osteoporosis that must be administered by a healthcare provider. Erythropoiesis-stimulating agents (ESAs), used to treat anemia associated with chronic conditions like End-Stage Renal Disease (ESRD) or chemotherapy, are covered when given by injection. Furthermore, blood clotting factors for people with hemophilia are covered, including those that may be self-administered in the home but are still billed through the physician or supplier.
Certain injectable drugs that are not usually self-administered and are provided as part of a physician’s service are included in this coverage. This ensures that patients receiving complex therapies, such as some monoclonal antibodies or certain immune globulin treatments, receive the necessary professional supervision. The payment for the drug itself is separate from the payment a facility or physician receives for the act of administering the injection or infusion.
Oral Drugs Covered Under Special Circumstances
While Part B generally excludes oral medications, there are specific, federally mandated exceptions to this rule. These exceptions cover certain oral drugs that are closely linked to therapies covered under Part B, ensuring comprehensive care for patients with specific conditions. These exceptions do not apply to general oral medications taken for chronic conditions, which remain the responsibility of a Part D prescription drug plan.
Oral Anti-Cancer and Anti-Nausea Drugs
One significant exception involves oral anti-cancer drugs, which are covered if the drug has an injectable equivalent that would be covered under Part B for the same use. This ensures that patients are not financially penalized for taking the oral form of a chemotherapy agent when it is medically appropriate. Similarly, oral anti-nausea drugs are covered, but only when they are used immediately before, during, or within 48 hours following a Part B-covered chemotherapy treatment.
Immunosuppressive Drugs
Immunosuppressive drugs are also covered for individuals who have received an organ transplant that Medicare paid for. This coverage helps prevent organ rejection following the procedure.
End-Stage Renal Disease (ESRD) Drugs
Medicare Part B covers all oral drugs used for End-Stage Renal Disease (ESRD), such as calcimimetic medications and phosphate binders, regardless of whether a drug is available in an injectable form.
Drugs Used with Durable Medical Equipment
Medicare Part B covers drugs that are necessary for the effective operation of certain durable medical equipment (DME) that is also covered by Part B. This coverage is based on the premise that the drug is integral to the function of the medical device prescribed for use at home. The DME itself must be medically necessary, able to withstand repeated use, and appropriate for home use.
A common example is liquid medication used in nebulizers for respiratory conditions, such as chronic obstructive pulmonary disease (COPD) or asthma. The medication, which is inhaled as a mist, is covered by Part B because it is administered via the covered nebulizer equipment. In this scenario, the drug is functionally inseparable from the equipment.
Another example involves drugs administered through external infusion pumps. If a medically necessary drug requires administration via a Part B-covered infusion pump, the drug itself is also covered. For individuals with diabetes, insulin used with an external insulin pump covered under Part B’s DME benefit is also included in this category.
Preventative Vaccines and Biologicals
Part B covers a specific, limited list of preventative vaccines, which are generally provided at no cost to the beneficiary. These vaccines are considered preventative services and are exceptions to the usual rule that most vaccines are covered under Part D.
Part B covers the following vaccines:
- The seasonal influenza (flu) shot, covered annually.
- Pneumococcal vaccines, which protect against pneumonia and other related infections. Coverage includes either a single dose or a two-dose series, depending on the individual’s age and health status.
- The Hepatitis B vaccine, but only for individuals considered to be at high or intermediate risk for the virus.
- The COVID-19 vaccine.
Most other vaccines, such as the shingles vaccine, are covered under Part D.