You’ve probably heard the phrase “Medicare Part D” thrown around at doctor’s appointments or in those AARP mailers.
But when it comes down to it, understanding what your plan actually covers can feel like trying to read a legal document in a foreign language.
And here’s the thing that catches most people off guard: there’s no single master list of covered drugs.
Let’s break down what Medicare Part D covers, what it never covers, how the whole system works, and what changes you need to know for 2025 and beyond.
The One Golden Rule: Your Mileage Will Vary
Here’s the first thing you need to know: there is no single, universal list of drugs covered by Medicare Part D.
Private insurance companies offer Part D plans, and each one creates its own list of covered drugs, called a formulary.
This is why one plan might cover your medication with a $10 copay, while another might not cover it at all or charge you $100. One plan might cover brand-name Humira, while another covers only its biosimilars.
The 2025 numbers you need to know:
- Average monthly premium for a stand-alone Part D plan: about $36
- Maximum annual deductible: $590
- New out-of-pocket spending cap for covered drugs: $2,000 per year (once you hit this, you pay nothing for the rest of the year)
Drugs Part D Plans Are Required to Cover
Even though plans have flexibility, Medicare law requires all Part D plans to cover “substantially all” drugs in six protected categories. These are considered essential for maintaining health:
- Antidepressants
- Antipsychotics
- Anticonvulsants (for seizure disorders)
- Antineoplastics (for cancer)
- Immunosuppressants (for transplant patients)
- HIV/AIDS treatments
This doesn’t mean every single drug in these categories is covered, but the plan must offer a robust selection. You won’t see a plan that simply decides not to cover cancer drugs at all.
Drugs That Medicare Part D NEVER Covers
Certain drugs are explicitly excluded from Part D coverage under federal law. No plan covers them under Part D. Period.
The Complete Exclusion List
| Category | Examples |
| Weight Loss, Gain, or Anorexia | Xenical, phentermine, Meridia |
| Fertility Drugs | Clomid, Gonal-f, Ovidrel, Follistim |
| Cosmetic/Hair Growth | Propecia, Renova, Vaniqa |
| Erectile Dysfunction / Sexual Dysfunction | Viagra, Cialis, Levitra, Muse, Caverject |
| Cough & Cold Relief | Phenergan w/Codeine, Robitussin AC, Tessalon Perle |
| Prescription Vitamins & Minerals | Except for prenatal vitamins and fluoride preparations. This means Nephrocaps, Foltx, and even Cyanocobalamin (vitamin B12) are excluded. |
| Over-the-Counter (OTC) Drugs | Any non-prescription product (except insulin and supplies for insulin injection) |
| Drugs Covered Under Part A or B | If Medicare Parts A or B already covers a drug (such as certain cancer drugs like Xeloda, Temodar, or Advate), Part D won’t cover it. |
| Bulk Chemicals & Ingredients | Sterile water for injection, normal saline IV flush, heparin lock flush |
| Devices & Medical Supplies | Diaphragms, Biafine, ethyl alcohol |
The Important Exception to the Weight Loss Rule
Here’s where it gets tricky. The “no weight loss drugs” rule has an important asterisk. Drugs used for weight loss that also treat other medical conditions may be covered.
Take Wegovy (semaglutide). Commonly known for weight loss, it was selected by Medicare for price negotiations in 2025.
In fact, in Medicare’s second round of drug price negotiations, they selected Ozempic, Rybelsus, and Wegovy together. This indicates these drugs are covered under Part D for their FDA-approved indications.
However, there’s a catch. Beginning January 1, 2025, many plans (like UnitedHealthcare) require prior authorization for GLP-1 agonists, requiring submission of medical records to confirm a diagnosis of type 2 diabetes before they will cover the drug.
How the Tier System Works?
Your cost for a drug depends entirely on which tier it’s on. Think of tiers like levels on a video game—the higher you go, the more it costs.
| Tier | Name | What It Means for Your Wallet |
| Tier 1 | Preferred Generic | Lowest cost. Generic drugs the plan wants you to use. |
| Tier 2 | Generic | Still generic, but slightly more expensive than Tier 1. |
| Tier 3 | Preferred Brand | Brand-name drugs the plan prefers. Higher copays than generics. |
| Tier 4 | Non-Preferred Drug | Higher cost generics and brands. The plan would prefer you try a lower-tier option first. |
| Tier 5 | Specialty | Very high-cost drugs for complex conditions. You typically pay a percentage of the total cost (coinsurance), not a flat copay. |
The 2025 Tier Changes to Watch
- Deductibles: For 2025, many Medicare Advantage members will see new or increased deductibles on Tier 3, 4, and 5 prescriptions.
- Supply Limits: UnitedHealthcare is limiting Tier 4 prescriptions to a 30-day supply instead of a 90-day supply starting in 2025.
- The Good News: Nearly all UnitedHealthcare Medicare Advantage members will continue to have $0 copays for Tier 1 prescriptions and no Part D deductibles for Tier 1 and 2 prescriptions.
Formulary Restrictions: When “Covered” Doesn’t Mean “Easy to Get”
Even if a drug is on the formulary, you can’t always just walk in and pick it up. You might see labels like this:
- Prior Authorization (PA): Your doctor needs to get approval from the plan before you fill the prescription. This has become especially common for expensive drugs like GLP-1 agonists.
- Quantity Limits (QL): The plan will cover only a set amount per fill (e.g., a 30-day supply instead of 90 days).
- Step Therapy (ST): You may need to try a cheaper drug first. If it doesn’t work, then the plan will cover the more expensive one.
Formularies Change! The 2025 & 2026 Updates
Drug formularies are not set in stone. Plans are updated periodically, and major changes usually occur at the beginning of the year.
2025 Formulary Removals (UnitedHealthcare)
The following table shows examples of drugs that were removed from UnitedHealthcare’s Medicare Advantage formularies in 2025 and their covered alternatives:
| Drug Removed | Covered Alternative |
| Epclusa (Hepatitis C) | Mavyret (requires prior authorization) |
| Levemir (Diabetes) | Lantus, Toujeo, Tresiba |
| Praluent (Cardiovascular) | Repatha (requires prior authorization) |
| Flovent (Respiratory) | Arnuity Ellipta, QVAR Redihaler, Pulmicort Flexhaler |
| Advair Diskus (Respiratory) | Symbicort, Wixela Inhub |
| Avonex / Rebif (Multiple Sclerosis) | Betaseron, generic Copaxone |
2026 Formulary Removals (UnitedHealthcare)
| Drug Removed | Covered Alternative |
| Tresiba (Diabetes) | Lantus, Toujeo |
| Humira (Autoimmune) | Humira biosimilars: adalimumab-AATY, adalimumab-ADBM |
| Orencia (Autoimmune) | Adalimumab-AATY, Enbrel, Otezla, Rinvoq, Skyrizi, Tremfya, Xeljanz |
| Motegrity (Constipation) | Lubiprostone, Linzess, Trulance |
| Vumerity (Multiple Sclerosis) | Bafiertam |
| Bevespi Aerosphere (Respiratory) | Anoro Ellipta, Stiolto Respimat |
What to Do If Your Drug ISN’T on the Formulary?
Finding out your prescription isn’t covered is frustrating. But you have options:
- Ask Your Doctor for a Covered Alternative: There’s a good chance there’s another drug in the same class that is covered. This is the easiest path.
- Request a Coverage Determination/Exception: You or your doctor can formally request that the plan cover your drug. You’ll need to provide a statement from your doctor explaining why the covered alternatives would be ineffective or harmful for you.
- Check Your Plan’s Formulary Carefully: Blue MedicareRx organizes its formulary alphabetically by drug category AND includes an alphabetical list by drug name near the back with page numbers. Use this to double-check you didn’t miss it.
Your Action Plan
Navigating Part D is a yearly task. Here’s how to make it easier:
- Get Your Formulary: Log in to your plan’s website and search for the “Formulary” or “Drug List.” You can search by drug name.
- Check Your Tiers: Look at which tier your medications are on to estimate your costs.
- Look for Restrictions: Check for any PA, QL, or ST symbols. If you see them, talk to your doctor now to prepare any necessary paperwork.
- Annual Review: Open Enrollment is October 15th through December 7th. Your formulary changes year to year. Don’t assume your plan is still the best fit for you.
Drowning in Prior Authorizations and Coverage Determinations?
| Every formulary restriction in this guide lands on a provider’s desk as paperwork. Prior authorizations, step therapy overrides, quantity limit exceptions, and coverage determination appeals pull staff away from patients and slow down payment. Medivantek Medical Billing Experts handle that work for practices across all 50 states.Our team verifies benefits before the visit, prepares and submits prior authorizations, and works Part B and Part D drug denials by root cause. Hence, patients get their medications, and the practice gets paid. Coverage determinations and exceptions are built and tracked, not left to age out.If prior authorization volume is buried in your team, or drug denials are piling up, let us take it off your plate. Request a free benefits and authorization review, and we will show you where the bottlenecks and the lost revenue are. |