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PlainMedicare

Is Xifaxan (rifaximin) covered by Medicare Part D?

5,052 of 5,052 Medicare Part D plan offerings (100%) list Xifaxan on their 2026 formulary, most often on tier 5; 96.6% of the formularies that cover it require prior authorization. Part D spending on it was $1.2 billion in 2024 for 104,805 people: what plans and patients paid at the pharmacy, before manufacturer rebates (CMS Part D Spending by Drug).

Plans that cover it
100%
5,052 of 5,052 offerings; the median drug: 76%
Usual tier
Tier 5
from tier 1 to tier 5
Prior authorization
96.6%
of formularies that cover it; the median drug: 1%
Quantity limits
65.2%
of formularies that cover it; the median drug: 30%

Source: CMS Part D formulary file, 2026 second quarter: the formularies in use in 2026. A plan's 2027 formulary can differ; check your own plan's coverage in Medicare Plan Finder.

What does it cost under Part D in 2027?

A negotiated price
Medicare negotiated a lower price for XIFAXAN, in effect from January 1, 2027: $1,000 for a 30-day supply, against a list price of $2,696 (2024). Where your share is a percentage of the drug's price, it is a percentage of the lower price; a flat copay stays as your plan sets it.
Your yearly cap in 2027
Out-of-pocket spending on covered Part D drugs stops at $2,400 in 2027 ($2,100 in 2026); after that, you pay nothing for covered drugs for the rest of the year.
The deductible
A plan's drug deductible is at most $700 in 2027 ($615 in 2026); many plans charge less or none.

Source: CMS, Announcement of calendar year 2027 Part D parameters; Medicare.gov, “How much does Medicare drug coverage cost?”; CMS, “Selected drugs and negotiated prices” (read Oct. 7, 2026).

How much does Medicare spend on it?

Part D spending by year

2020$845 million
2021$890 million
2022$970 million
2023$1.1 billion
2024 (latest)$1.2 billion

104,805 people filled it under Part D in 2024, in 416,690 claims. The amounts are what plans and patients paid at the pharmacy, before manufacturer rebates.

Source: CMS Medicare Part D Spending by Drug, 2020 to 2024 (published June 2026). Row used: Xifaxan (Rifaximin).

Which forms and strengths are counted?

  • rifaximin 200 mg oral tablet
  • rifaximin 550 mg oral tablet

What else should you check?

Data, not medical advice. Coverage is the share of plan formularies listing the drug; your plan's formulary, tier and pharmacy decide what you pay.