Drug plan coverage rules


Call your Medicare drug plan to find out the specific drug coverage rules for your plan.

Medicare drug plans may have these coverage rules:

Opioid pain medication safety checks

When you fill a prescription at the pharmacy, Medicare drug plans and pharmacists routinely check to make sure the prescription is correct, that there are no interactions, and that the medication is appropriate for you. They also conduct safety reviews to monitor the safe use of opioids and other frequently abused medications. These reviews are especially important if you have more than one doctor who prescribes these drugs. In some cases, the Medicare drug plan or pharmacist may need to first talk to your doctor before the prescription can be filled.

Your drug plan or pharmacist may do a safety review when you fill a prescription if you:

  • Take potentially unsafe opioid amounts as determined by the drug plan or pharmacist.
  • Take opioids with benzodiazepines like Xanax®, Valium®, and Klonopin®.
  • Are newly using opioids—you may be limited to an initial 7-day supply or less, to decrease the likelihood of addiction or long-term use. 

If your pharmacy can’t fill your prescription as written, the pharmacist will give you a notice explaining how you or your doctor can call or write to your plan to ask for a coverage decision. If your health requires it, you can ask the plan for a fast coverage decision. You may also ask your plan for an exception to its rules before you go to the pharmacy, so you’ll know if your plan will cover the medication.

For certain drugs, Medicare drug plans might perform additional safety checks, and will send your pharmacy an alert for review before your prescription is filled. Safety alerts may cover situations like:

  • Possible unsafe amounts of opioids. Your pharmacist or Medicare drug plan may need to review your prescription with your doctor to make sure the medications are safe.
  • First prescription fills for opioids. You may be limited to a 7-day supply or less if you haven’t recently taken opioids.
  • Use of opioids and benzodiazepines at the same time.

If your prescription can’t be filled as written, including the full amount on the prescription, the pharmacist will give you a notice explaining how you or your doctor can contact the plan to ask for a coverage determination. You may also ask your plan for an exception to its rules before you go to the pharmacy to buy the medication, so that your prescription is covered.

Drug management programs

Some Medicare drug plans have a drug management program in place to help you use these opioids and benzodiazepines safely. If your opioid use could be unsafe (for example, due to getting opioid prescriptions from multiple doctors or pharmacies), or if you had a recent overdose from opioids, your plan will contact the doctors who prescribed them for you to make sure they’re medically necessary and you’re using them appropriately.

If your Medicare drug plan decides your use of prescription opioids and benzodiazepines may not be safe, the plan will send you a letter in advance. This letter will tell you if the plan will limit coverage of these drugs for you, or if you’ll be required to get the prescriptions for these drugs only from a doctor or pharmacy that you select.

Before your Medicare drug plan places you in its drug management program, it will notify you by letter, and you’ll be able to tell the plan which doctors or pharmacies you prefer to use. You and your doctor can appeal if you disagree with your plan’s decision or think the plan made a mistake.


The opioid safety reviews and drug management programs generally won’t apply to you if you have cancer or sickle cell disease, get hospice, palliative, or end-of-life care, or if you live in a long-term care facility.

Important tips if you're prescribed opioids

  • Opioid medications can be an important part of pain management, but they also can have serious health risks if misused.
  • Talk with your doctor about having naloxone at home. Medicare covers naloxone, a drug that your doctor may prescribe as a safety measure in case you need to rapidly reverse the effects of an opioid overdose.
  • Talk with your doctor about your dosage and the length of time you’ll be taking them. You and your doctor may decide later you don’t need to take all of your prescription.
  • Talk with your doctor about other options that Medicare covers to treat your pain, like non-opioid medications and devices, physical therapy, acupuncture for lower back pain, individual and group therapy, behavioral health integration services, and more.
  • Never take more opioids than prescribed. Also, talk with your doctor about any other pain medicines you’re taking.
  • Safely store and dispose of unused prescription opioids through your community drug take-back program or your pharmacy mail-back program.
Prior Authorization
During the COVID-19 pandemic, Medicare Advantage Plans and Prescription Drug Plans may waive or relax prior authorization requirements. Check with your plan for more information.

You and/or your prescriber must contact your plan before you can fill certain prescriptions. Your prescriber may need to show that the drug is medically necessary for the plan to cover it. Plans may also use prior authorization when they cover a drug for only certain medical conditions it is approved for, but not others. When this occurs, plans will likely have alternative drugs on their list of covered drugs (formulary) for the other medical conditions the drug is approved to treat.

Quantity limits

For safety and cost reasons, plans may limit the amount of prescription drugs they cover over a certain period of time. For example, most people prescribed heartburn medication take 1 tablet per day for 4 weeks. Therefore, a plan may cover only an initial one month supply of the heartburn medication.

If your prescriber believes that, because of your medical condition, a quantity limit isn’t medically appropriate (for example, your doctor believes you need a higher dosage of 2 tablets per day), you or your prescriber can contact the plan to ask for an 



Step therapy

Step therapy is a type of 

prior authorization [glossary]

. In most cases, you must first try a certain, less expensive drug on the plan’s 


 that’s been proven effective for most people with your condition before you can move up a “step” to a more expensive drug. For instance, some plans may require you first try a generic drug (if available), then a less expensive brand-name drug on their drug list before you can get a similar, more expensive, brand-name drug covered.

However, if your prescriber believes that because of your medical condition it’s medically necessary for you to be on a more expensive step therapy drug without trying the less expensive drug first, you or your prescriber can contact the plan to request an 



Your prescriber can also request an exception if he or she believes you’ll have adverse health effects if you take the less expensive drug, or if your prescriber believes the less expensive drug would be less effective. Your prescriber must give a statement supporting the request. If the request is approved, the plan will cover the more expensive drug, even if you didn’t try the less expensive drug first. 

Example of step therapy

Step 1—Dr. Smith wants to prescribe an ACE inhibitor to treat Mr. Mason’s heart failure. There’s more than one type of ACE inhibitor. Some of the drugs Dr. Smith considers prescribing are higher-cost ACE inhibitors covered by Mr. Mason’s Medicare drug plan. The plan rules require Mr. Mason to use a lower-cost ACE inhibitor first. For most people, the lower-cost drug works as well as the higher-cost drug.

Step 2—If Mr. Mason takes the lower-cost drug but has side effects or limited improvement, Dr. Smith can prescribe the higher-cost ACE inhibitor.

Part D vaccine coverage

Except for vaccines covered under 

Medicare Part B (Medical Insurance)

, Medicare drug plans must cover all commercially available vaccines (like the shingles vaccine) when medically necessary to prevent illness.

Drugs you get in hospital outpatient settings

In most cases, the prescription drugs you get in a 

hospital outpatient setting

, like an emergency department or during observation services, aren't covered by 

Medicare Part B (Medical Insurance)

. These are sometimes called "self-administered drugs" that you would normally take on your own. Your Medicare drug plan may cover these drugs under certain circumstances.

You'll likely need to pay out-of-pocket for these drugs and submit a claim to your drug plan for a refund. Or, if you get a bill for self-administered drugs you got in a doctor's office, call your Medicare drug plan for more information.

If you or your prescriber believe that one of these coverage rules should be waived, you can ask your plan for an exception