Fosfomycin powder for oral solution (Monurol and others)

How Medicare covers it

Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

What it treats

Uncomplicated urinary tract infection (acute cystitis — a simple bladder infection) in women, caused by susceptible strains of E. coli and Enterococcus faecalis.

What it is for, in depth

Fosfomycin is prescribed for women with a simple, uncomplicated bladder infection — burning and frequency from acute cystitis — where the infecting bacteria are susceptible E. coli or Enterococcus faecalis. Its single-dose format is its place in the treatment path: one drink replaces a multi-day antibiotic course for this narrow use, and it is not a substitute for multi-day therapy when the infection involves the kidneys. It comes as one single-dose sachet of granules equivalent to 3 grams of fosfomycin.

How it works

Fosfomycin is a broad-spectrum antibiotic that kills bacteria (bactericidal). After swallowing, it is rapidly absorbed and reaches the kidneys and bladder wall, where it works against the bacteria causing the infection.

How it is taken

One single dose for women 18 and older: empty the whole sachet (3 grams of fosfomycin) into water, stir, and drink it — never take it dry. It may be taken with or without food (food lowers absorption somewhat).

Common side effects

In trials, the effects reported in more than 1% of fosfomycin-treated patients were diarrhea (9%), vaginitis (5.5%), nausea (4.1%), headache (3.9%), dizziness (1.3%), weakness (1.1%), and indigestion (1.1%). Overall, headache and diarrhea were each reported by about 1 in 10 patients.

Serious warnings

It is for uncomplicated bladder infection only — it is NOT indicated for kidney infection (pyelonephritis) or a perinephric abscess. If bacteria persist or come back in the urine after treatment, a different antibiotic should be chosen. The only contraindication is known hypersensitivity to the drug.

Who should be careful

Anyone allergic to fosfomycin must not take it. People whose urinary bacteria persist or return after the single dose need a different therapeutic agent, per the label.

Major interactions

Metoclopramide lowers fosfomycin blood levels and urine excretion, and other drugs that speed up gut motility may do the same. Cimetidine does not affect fosfomycin levels.

Cost and saving notes

Fosfomycin is covered under Medicare Part D as a single-dose product. If your plan's tier makes it hard to afford, you can ask your plan for a tier exception. If you qualify for Extra Help, the Part D low-income help, your drug costs will be much lower.

Why it is in its tier

Fosfomycin powder for oral solution (Monurol and others) sits on Tier 4 in 79.75% of the plans that list it (4382 of 5495 listing plans). Tier 4 is the non-preferred tier — higher copays or coinsurance. The data-visible drivers: It is a generic product, and the CMS dashboard puts its average Part D spending at about $283 per beneficiary for 2024 — a relatively low-cost drug, which matches where plans place it. It is listed by 100.0% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• FOSFOMYCIN TROMETHAMINE GRANULE, FOR SOLUTION [ANI PHARMACEUTICALS, INC.] — DailyMed
• MedlinePlus — Fosfomycin

What official patient guides say

Fosfomycin comes as granules to be mixed with water and then taken by mouth. Take it once as a single dose, with or without food, exactly as directed — do not take more or less of it or take it more often than prescribed by your doctor. Fosfomycin must be mixed with water before you take it: pour the entire contents of a single-dose packet into a glass and add 3 to 4 ounces (90 to 120 milliliters) of cold water, stir to dissolve, and do not use hot water. Take the dose by mouth as soon as it is prepared, and do not take the granules without mixing them with water first. Your symptoms should improve 2 to 3 days after taking fosfomycin; if they have not improved after 2 to 3 days, call your doctor. If you forget a dose, take it as soon as you remember it; if it is almost time for the next dose, skip the missed dose and continue your regular schedule — do not take a double dose. Keep it in the container it came in, tightly closed and out of reach of children. Store it at room temperature, away from excess heat and moisture, and not in the bathroom.

Source: MedlinePlus — Fosfomycin

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

Without insurance, the cash benchmark is 26.36958 per unit (FOSFOMYCIN 3 GM SACHET) — about nan for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 5,495 list Fosfomycin powder for oral solution (Monurol and others) — 100% of plans. Most of those plans put it on Tier 4: 4,382 plans, 79.8% of the plans that list it. Other plans place it on Tier 3 (554 plans), Tier 2 (425 plans) or Tier 1 (134 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 4; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 4; Aetna Medicare Value Plus (PPO) puts it on Tier 4. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.