14 Prescription Drugs Medicare Part D Won’t Cover in 2026

Medicare Part D helps roughly 54.8 million of older Americans — nearly 80% of all Medicare enrollees — afford prescription drugs.

But rules on what's covered are always changing. Even if have a valid prescription, Part D may not cover it.

Here's a look at some 2026 plan restrictions. Before you refill your next prescription, make sure you know what's covered to avoid money mistakes at the counter.

About Medicare Part D

Medicare Part D is the part of Medicare that covers prescription drugs.

Private insurers — such as Humana, Aetna, and UnitedHealthcare — offer these plans and must follow federal rules about which medications they cover and how formularies (prescription and generic) are managed.

Part D generally helps pay for prescriptions filled at a pharmacy, and each plan has tiers that determine how much you owe.

As an example, here's the tier structure of one major carrier:

• Tier 1: Lowest copayment; for preferred drugs (common generics).
• Tier 2: Medium copayment; covers many generic drugs.
• Tier 3: Higher copayment; common or "preferred" brand-name drugs and some higher-cost generics
• Tier 4: High copayment; non-preferred drugs – brand-name and generic
• Tier 5: Highest copayment; for specialty tier for unique and exceptionally high-cost brand and generic drugs

Medicare Part D enrollment

You can enroll in Medicare Part D when you first become eligible for Medicare — usually at age 65 — or during annual open enrollment.

Most people pay monthly premiums, deductibles, and cost-sharing amounts depending on their plan's structure.

What does Medicare Part D cover?

Part D generally covers FDA-approved medications that are medically necessary to tread conditions and on your plan's formulary.

Plans must cover drugs in protected classes, such as antidepressants, anticonvulsants, antiretrovirals, immunosuppressants, antipsychotics, and anticancer drugs.

Is there a list of all medications that are excluded?

The short answer is no. Medicare Part D does not publish one universal list of excluded drugs.

Instead, Medicare requires plans to exclude entire categories, such as drugs used for weight management, cosmetic purposes, or erectile dysfunction.

Plans may also exclude certain brand-name drugs if lower-cost biosimilars are available.

Prescription drugs not covered by Medicare Part D in 2026

Here's a list of some of the most commonly prescribed drugs not covered by Medicare Part D in 2026. This list is not all-inclusive, and many excluded drugs were also excluded in years prior.

Humira

Humira has been one of Medicare's most expensive medications, but many Part D plans are moving from the brand-name drugs for lower-cost biosimilars.

In recent years, there has been a strong push away from Humira to lower costs. If prescribed Humira, you may need to pay $6,922 a month out of pocket — or switch to a generic alternative.

Viagra, Cialis, and other drugs treating erectile dysfunction

Part D excludes all medications used to treat erectile dysfunction (ED), including Viagra and Cialis.

In limited cases, Medicare Part D will approve a generic version If prescribed for medical conditions not related to ED, such as pulmonary hypertension.

Wegovy, Ozempic, Xenical, and other Rx drugs for weight loss

Weight-loss medications — including Wegovy or Ozempic when used for weight loss, and Xenical — are excluded entirely from Medicare Part D.

However, Ozempic and other related drugs may be covered if they're used to treat Type-2 diabetes.

Without any coverage, patients can expect to pay around $1,350 a month for a one-month subscription of Wegovy, or up to $900 for a 90-day prescription of Xenical.

Finasteride, minoxidil, and other medications for hair loss

Drugs used solely for hair loss — such as finasteride and minoxidil — are not covered under Part D because cosmetic treatments fall outside federally approved categories.

Out of pocket, these drugs may cost around $100 to $250 a month.

Renova and drugs for cosmetic purposes

Drugs prescribed solely for cosmetic purposes, like Renova, are excluded from Part D plans.

These medications may help with wrinkles, skin tone, or other aesthetic concerns, but Medicare only covers drugs considered medically necessary.

Without coverage, Renova may cost around $70 to $160 a month.

Prescription Robitussin AC, Phenergan, and other Rx drugs for acute cough

Part D generally does not cover prescription cough syrups like Robitussin AC or certain formulations of Phenergan.

These drugs are often excluded as short-term, symptomatic treatments that do not meet Medicare's criteria for covered prescription benefits.

Doctor-proscribed OTC drugs like Miralax, Claritin, or Tylenol

Even if your doctor prescribes an over-the-counter product like Miralax, Claritin, or Tylenol, Medicare Part D will not cover it.

However, If a higher-dose, prescription-only version of an OTC is prescribed, then that exclusion may not apply.

Prescription eyeglasses or corrective lenses

Part D does not cover prescription eyeglasses, contact lenses, or routine eye exams. However, medications used to treat eye disease are covered.

Previously covered drugs may lose coverage

Some high-cost brand-name drugs face tighter restrictions in 2026. Others may remain covered, but increasingly subject to step therapy, prior authorizations, or requirements to try generics first.

What if your medication isn't covered?

If your medication isn't covered, you have other options.

Your doctor can request an exception, prescribe a covered alternative, or help you appeal the denial. In cases of medical necessity, such as being unable to tolerate a cheaper drug, Part D may approve non-formulary medications.

Alternatives to Medicare Part D

If your medication remains uncovered, you can look into GoodRx discounts, manufacturer coupons, and pharmacy discount programs.

In some instances, patients my find more affordable options in Canada or further abroad. Switching to a different Part D plan during open enrollment may also reduce costs.

Bottom line

Medicare Part D offers strong coverage for many drugs, but it excludes prescriptions for weight management, sexual dysfunction, or vitamins and minerals.

As more plans shift toward generics to lower prices, coverage will continue to evolve.

Staying informed can help you manage prescription costs and make smart money moves. While the 2026 enrollment window has closed, eligible participants can still sign up. The late penalty is an extra 1% for each month (or 12% a year). Or you can avoid the penalty altogether if you had creditable drug coverage (similar in value) prior to your late Part D enrollment.

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