Medicare Part D excludes several categories of drugs by federal law, meaning no Part D plan can cover them regardless of medical necessity. These statutory exclusions are different from a plan simply leaving a drug off its formulary. If your drug falls into an excluded category, you can’t appeal or request an exception. If it’s just not on your plan’s formulary, you can.
Drugs Excluded by Federal Law
Congress wrote specific drug categories out of Part D coverage entirely. These are not optional decisions made by individual insurance plans. No Part D plan, whether standalone or bundled with Medicare Advantage, is permitted to cover them under the standard benefit. The excluded categories are:
- Drugs for cosmetic purposes or hair growth. Medications prescribed purely for appearance, including hair regrowth treatments, are excluded. However, treatments for skin conditions like psoriasis, acne, rosacea, or vitiligo are not considered cosmetic and can be covered.
- Drugs for erectile dysfunction or sexual dysfunction. This exclusion was added in 2005. If the same drug is FDA-approved for a different condition, like pulmonary hypertension, Part D can cover it for that purpose. But it will not cover it for sexual dysfunction under any circumstances.
- Prescription vitamins and minerals. This includes prescription-strength vitamin D (both D2 and D3), B vitamins like folic acid and B12, vitamin K, iron, zinc, and iodine. Two narrow exceptions exist: prenatal vitamins and fluoride preparations are covered. Certain vitamin D analogs (synthetic versions used to treat conditions like kidney disease) are also not excluded, because CMS considers them distinct from standard vitamin D supplements.
- Drugs for weight loss or weight gain. Medications prescribed solely to manage body weight have historically been excluded. This category has recently gotten more complicated with GLP-1 drugs, which are covered below.
- Drugs for cough and cold symptoms. Prescription medications used only for symptomatic relief of coughs and colds fall outside Part D coverage.
- Drugs for fertility. Medications to promote or prevent conception are excluded.
- Over-the-counter medications. Even when a doctor writes a prescription for an OTC product, Part D does not cover it. Federal law prohibits plans from including OTC drugs as part of their drug benefit or supplemental coverage. Some Medicare Advantage plans offer a separate OTC allowance as an extra benefit, but that is not Part D coverage.
The GLP-1 Weight Loss Exception
GLP-1 medications like semaglutide and tirzepatide sit at the intersection of several Part D rules. When prescribed for type 2 diabetes, these drugs are standard Part D drugs and can appear on plan formularies like any other medication. When prescribed to reduce cardiovascular risk in people with established heart disease and obesity, or for obstructive sleep apnea in adults with obesity, they also qualify for Part D coverage because the indication goes beyond weight loss alone.
Pure weight loss use has historically been excluded. But starting in 2026, a new program called the Medicare GLP-1 Bridge creates a pathway for coverage. To qualify, a prescriber must submit a prior authorization confirming the patient meets specific criteria. The thresholds vary by health status: a BMI of 35 or higher with no additional conditions, a BMI of 30 or higher with conditions like uncontrolled hypertension or chronic kidney disease (stage 3a or above), or a BMI of 27 or higher with conditions like pre-diabetes, prior heart attack, prior stroke, or symptomatic peripheral artery disease. The patient must also be at least 18 and combining the medication with lifestyle changes including structured nutrition and physical activity.
Drugs Covered by Part B Instead
Some prescription drugs aren’t covered by Part D because they already fall under Medicare Part B. This isn’t technically an “exclusion” in the same way, but it catches people off guard when their Part D plan rejects a claim for a drug that Medicare does cover, just under a different part of the program.
Part B generally covers drugs that are not self-administered. This includes most medications given by injection or infusion in a doctor’s office, such as chemotherapy drugs, certain rheumatology infusions, and injectable treatments given by urologists and other specialists. Part B also covers drugs administered through durable medical equipment at home, like certain intravenous medications for heart failure and pulmonary arterial hypertension, as well as some immune globulin infusions.
The dividing line is fairly simple: if a healthcare professional administers the drug in a clinical setting, or it requires covered medical equipment to deliver, Part B typically handles it. If you pick up a prescription at a pharmacy and take it yourself, that’s Part D territory.
Not on the Formulary vs. Excluded by Law
There’s a critical distinction between a drug that Medicare is legally prohibited from covering and a drug your specific plan chose not to include on its formulary. If your medication is in one of the excluded categories listed above, no appeal or exception request will change that. The law forbids coverage.
If your drug is simply not on your plan’s formulary but is otherwise a valid Part D drug, you have options. You can file an exception request asking your plan to cover it. Your doctor will need to explain why the formulary alternatives won’t work for you. If the plan denies the request, you can appeal through a formal process. Many enrollees successfully get non-formulary drugs covered this way.
The easiest way to tell the difference: check whether any Part D plan in your area covers the drug. If none do, it’s likely a statutory exclusion. If some plans cover it but yours doesn’t, it’s a formulary decision you can challenge. Medicare’s online plan finder lets you search by drug name to compare formularies across plans in your area, which is especially useful during open enrollment when you can switch to a plan that already covers what you need.
What Enhanced Plans Can Add
Part D plans come in two tiers: basic and enhanced. Basic plans follow the standard benefit structure set by Medicare. Enhanced plans charge a higher premium but can offer additional coverage, like lower copays or coverage during the gap phase. However, even enhanced plans cannot cover drugs in the statutory exclusion categories. An enhanced plan might cover more drugs or offer better cost-sharing on covered medications, but it still operates within the same legal boundaries as every other Part D plan. No amount of premium buys coverage for a federally excluded drug.