Fosfomycin
Fosfomycin is an antibiotic used to treat urinary tract infections: the oral form for uncomplicated bladder infections in women, and the intravenous (IV) form for complicated urinary tract infections in adults.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 8 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Fosfomycin is an antibiotic that kills bacteria by blocking MurA, an enzyme they need to build their cell walls; the oral sachet (Monurol, on the U.S. market since about 1996 and available generically) is one of the standard first choices for a simple bladder infection in women, and the IV (into a vein) form, Contepo, treats complicated urinary tract infections, including kidney infection, in adults. The single oral dose is usually well tolerated, with diarrhea, nausea or headache the effects people notice most. The one to watch for is severe or lasting diarrhea, even weeks or months later, which can signal C. difficile, a serious bowel infection that can follow antibiotics.
Clinical pearls
- Mix the whole sachet into half a cup of cool water, drink it right away, and never take granules dry.
- One sachet is the whole course, so if bladder symptoms linger or come back, contact your prescriber about a different antibiotic.
- On Contepo, report a racing or irregular heartbeat or fainting; antipsychotics and macrolide antibiotics can add to this heart rhythm risk.
- Each Contepo vial carries a lot of sodium, so mention heart failure, cirrhosis or a low-salt diet, and report any swelling.
Patient information guide A plain-language walkthrough of Fosfomycin, written from its FDA label.
What Fosfomycin is used for
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Fosfomycin is an antibiotic for urinary tract infections. Approved uses differ by product.
- Fosfomycin Tromethamine (oral): uncomplicated urinary tract infections (acute cystitis) in women, caused by susceptible E. coli and Enterococcus faecalis.
- Contepo (IV): complicated urinary tract infections, including acute pyelonephritis, in adults 18 and older, caused by susceptible E. coli and Klebsiella pneumoniae.
- Oral fosfomycin tromethamine is not for pyelonephritis or perinephric abscess.
How Fosfomycin works
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Fosfomycin blocks MurA, an enzyme bacteria need to make peptidoglycan, a key part of their cell wall. Without it, the bacteria cannot build a wall and die. It gets into bacterial cells through two transport systems.
Bacteria can become resistant through mutations that reduce how much drug gets in or that change the binding site. Some can also make enzymes that inactivate it.
Fosfomycin dosage
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The oral form is a single-dose sachet of granules dissolved in water. The IV form, Contepo, is given by a healthcare professional.
- Oral: Mix the whole sachet in about 1/2 cup of cool water, stir and drink right away. Do not take it dry. Food does not matter.
- Contepo: 1-hour IV infusion, repeated through the day, for up to 14 days. The dose is changed for reduced kidney function and given after dialysis on dialysis days.
Follow your prescriber and the product label.
Dosing details from the FDA-approved label
From the Fosfomycin prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Patients 18 years of age or older with estimated creatinine clearance (CLcr) greater than 50 mL/min (Contepo, intravenous)
- 6 grams every 8 hours by intravenous (IV) infusion over 1 hour for up to 14 days
- Duration of therapy is up to 14 days and should be guided by the severity of infection and the patient's clinical status
- Patients 18 years and older with estimated CLcr 41-50 mL/min (Contepo, intravenous)
- Loading dose 6 grams, then maintenance dosage 4 grams every 8 hours, each by IV infusion over 1 hour
- CLcr estimated by Cockcroft-Gault Equation; monitor CLcr and adjust dosage
- Patients 18 years and older with estimated CLcr 31-40 mL/min (Contepo, intravenous)
- Loading dose 6 grams, then maintenance dosage 3 grams every 8 hours, each by IV infusion over 1 hour
- CLcr estimated by Cockcroft-Gault Equation; monitor CLcr and adjust dosage
- Patients 18 years and older with estimated CLcr 21-30 mL/min (Contepo, intravenous)
- Loading dose 6 grams, then maintenance dosage 5 grams every 24 hours, each by IV infusion over 1 hour
- CLcr estimated by Cockcroft-Gault Equation; monitor CLcr and adjust dosage
- Patients 18 years and older with estimated CLcr 11-20 mL/min (Contepo, intravenous)
- Loading dose 6 grams, then maintenance dosage 3 grams every 24 hours, each by IV infusion over 1 hour
- Approximately 60 to 80% of the dose is cleared by hemodialysis; administer after hemodialysis on hemodialysis days
- Women 18 years of age and older with uncomplicated urinary tract infection (acute cystitis) (fosfomycin tromethamine, oral)
- One sachet of fosfomycin tromethamine granules for oral solution, mixed with 3 to 4 ounces of water (1/2 cup) and taken immediately after dissolving
- May be taken with or without food; do not take in dry form; do not use hot water
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION The recommended dosage for women 18 years of age and older for uncomplicated urinary tract infection (acute cystitis) is one sachet of fosfomycin tromethamine granules for oral solution. Fosfomycin tromethamine granules for oral solution may be taken with or without food. Fosfomycin tromethamine granules for oral solution should not be taken in its dry form. Always mix fosfomycin tromethamine granules for oral solution with water before ingesting. (See PREPARATION section.) PREPARATION Fosfomycin tromethamine granules for oral solution should be taken orally. Pour the entire contents of a single-dose sachet of fosfomycin tromethamine granules for oral solution into 3 to 4 ounces of water (1/2 cup) and stir to dissolve. Do not use hot water. Fosfomycin tromethamine granules for oral solution should be taken immediately after dissolving in water.
Read the full Dosage and Administration section on DailyMed →
Fosfomycin side effects
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Common side effects include:
Common side effects
- Nausea
- Vomiting
- Diarrhea
- Headache
- Low potassium, calcium or phosphorus levels on blood tests (Contepo)
- High sodium on blood tests (Contepo)
- Raised liver enzymes on blood tests (Contepo)
- Low white blood cell count (neutropenia) (Contepo)
When to get medical help
- Get help right away for a rash, hives, swelling or trouble breathing, which can signal a serious allergic reaction.
- Call your doctor if you have severe or persistent diarrhea, even weeks or months after treatment. It can be a sign of C. difficile infection.
- Tell your care team about a fast or irregular heartbeat, fainting or dizziness while on Contepo, which can signal a QT heart rhythm problem.
- Report swelling or fluid retention while on Contepo.
- If symptoms do not go away or come back after treatment, contact your doctor, because a different antibiotic may be needed.
- After an overdose of oral fosfomycin, hearing loss, balance problems or changes in taste have been seen.
Fosfomycin warnings and precautions
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- Contepo and QT prolongation: it can lengthen the QT interval, which may lead to dangerous rhythms such as torsade de pointes. Avoid it if you have known QT prolongation or ventricular arrhythmias.
- Contepo and electrolytes: the high sodium load can change blood sodium, potassium, calcium and phosphorus. Low-sodium diet and monitoring are recommended, and watch for swelling.
- Contepo and blood tests: liver enzymes and blood counts should be monitored. Neutropenia, including agranulocytosis (a severe drop in white blood cells), has been reported with IV fosfomycin.
- Allergic reactions: rash, hives and anaphylaxis have been reported with Contepo.
- C. difficile diarrhea: possible with all fosfomycin products, even more than 2 months after treatment.
- Use only for bacterial infections, to limit resistance.
Fosfomycin interactions
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The main interaction concern is with Contepo and heart rhythm.
- QT-prolonging drugs (class IA or III antiarrhythmics, tricyclic antidepressants, macrolides, antipsychotics): together they raise the risk of ventricular arrhythmia.
- Drugs affecting electrolytes or containing sodium: they can add to Contepo's electrolyte effects.
Interactions listed in the FDA-approved label
From the Fosfomycin prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Drugs known to prolong the QT interval, such as class IA or class III antiarrhythmic medications, tricyclic antidepressants, macrolides, and antipsychotics: Co-administration with Contepo may increase the risk for ventricular arrhythmia. Avoid co-administration of Contepo with drugs known to prolong the QT interval.
Read the label’s full interactions text
Drug Interactions Metoclopramide: When coadministered with fosfomycin tromethamine granules for oral solution, metoclopramide, a drug which increases gastrointestinal motility, lowers the serum concentration and urinary excretion of fosfomycin. Other drugs that increase gastrointestinal motility may produce similar effects. Cimetidine: Cimetidine does not affect the pharmacokinetics of fosfomycin when coadministered with fosfomycin tromethamine granules for oral solution.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Fosfomycin
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- Do not use if you have had a serious allergic reaction to fosfomycin or its ingredients (Contepo contraindication).
- Oral products are for women with uncomplicated bladder infections.
- Contepo has not been established in anyone under 18.
- Contepo: tell your doctor about heart rhythm problems, kidney disease, heart failure, cirrhosis, high blood pressure or a need to limit sodium.
- Contepo: pregnancy data are insufficient. Do not breastfeed during treatment and for 24 hours after the last dose.
- Contepo: adults 65 and older had lower success rates and more side effects in the trial.
Fosfomycin overdose
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In people who took too much oral fosfomycin tromethamine, vestibular loss (balance problems), impaired hearing, a metallic taste and reduced sense of taste were seen. Treatment is symptomatic and supportive. Seek medical help right away if you think too much was taken.
What Fosfomycin does in the body
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Fosfomycin's effect against bacteria relates to how much unbound drug is in the blood compared with the level needed to stop the infecting germ. In a study of healthy adults, Contepo caused a dose-dependent rise in the QTcF (a heart rhythm measure). It did not meaningfully change heart rate or conduction.
How your body processes Fosfomycin
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After a 1-hour IV infusion, fosfomycin is not bound to blood proteins and is not metabolized. Its half-life is about 2.8 hours. Most of it (70% at 12 hours) leaves unchanged in the urine, which is why it reaches the urinary tract well. People with reduced kidney function need dose adjustment, and dialysis removes much of the drug.
How to store Fosfomycin
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Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F).
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Fosfomycin
44 supplements and herbal products have documented interactions with Fosfomycin in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 1
- Moderate · 33
- Minor · 10
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Nutrient depletion considerations
Fosfomycin has been associated with lower levels of 7 nutrients in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
- Higher significance · 6
- Moderate · 1
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
Fosfomycin: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Fosfomycin — the kind of thing our pharmacy team would talk through with you at the counter.
What is fosfomycin used for?
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How do I take the oral granules?
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What side effects should I expect?
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When should I call my doctor?
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Are there medicine interactions I should know about?
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Can I use it if I'm pregnant or breastfeeding?
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Is Fosfomycin available over the counter?
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When was Fosfomycin first available?
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Who makes Fosfomycin?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Fosfomycin on HelloPharmacist
Fosfomycin forms and strengths (how it comes)
Fosfomycin is available in 3 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Fosfomycin inactive ingredients by manufacturer.
Oral solution
How this form is used
- Fosfomycin Tromethamine granules for oral solution treat uncomplicated urinary tract infections (acute cystitis) in women.
- Fosfomycin Tromethamine granules are mixed in 3 to 4 ounces of water, not hot water, and taken right away.
- Fosfomycin Tromethamine can be taken with or without food.
Injection
How this form is used
- Contepo treats complicated urinary tract infections, including acute pyelonephritis, in adults 18 and older.
- Contepo is for infections caused by susceptible E. coli and Klebsiella pneumoniae.
- Contepo is given as an IV infusion over 1 hour, about every 8 hours for people with normal kidney function, for up to 14 days.
- Contepo dosing is adjusted for reduced kidney function.
- Contepo is supplied as a powder that is mixed and diluted before infusion.
Oral powder
How this form is used
- Fosfomycin Tromethamine treats uncomplicated urinary tract infections (acute cystitis) in women.
- Fosfomycin Tromethamine is taken as one single-dose sachet mixed in water.
- Fosfomycin Tromethamine can be taken with or without food.
- Fosfomycin Tromethamine should never be taken dry.
Fosfomycin on the U.S. market: products, makers and brands
How Fosfomycin appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
9 companies list 9 Fosfomycin product records with the FDA, mostly as oral solution, injection, oral powder; the earliest marketing or approval year on record is 1996. Brand names on the directory include Monurol Sachet, Contepo; the rest are generics.
FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (10) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
How widely Fosfomycin is used (Medicaid data)
A general measure of how commonly Fosfomycin is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Fosfomycin is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Fosfomycin prescribed? Of the 1,601 medications we measure, Fosfomycin ranks #777 by Medicaid prescriptions — more than 51% of them.
Utilization by Fosfomycin product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
fosfomycin 3000 MG Granules for Oral Solution
Summed across the 4 of 18 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 808917
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Fosfomycin, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 4 of 18 listed Fosfomycin NDCs with Medicaid activity.
Compare Fosfomycin products
A representative set of FDA-listed product records for Fosfomycin — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 6 g | Intravenous | Meitheal Pharmaceuticals Inc. | NDA | View NDC → |
| 💊Oral powder | ||||
| 3 g | Oral | Precision Dose, Inc. | ANDA | View NDC → |
| 💊Oral solution | ||||
| 3 g | Oral | A-S Medication Solutions | ANDA | View NDC → |
| 3 g | Oral | Amneal Pharmaceuticals NY LLC | ANDA | View NDC → |
| 3 g | Oral | Ascend Laboratories, LLC | ANDA | View NDC → |
| 3 g | Oral | Aucta Pharmaceuticals, Inc. | ANDA | View NDC → |
| 3 g | Oral | Aurobindo Pharma Limited | ANDA | View NDC → |
| 3 g | Oral | Cipla USA Inc. | ANDA | View NDC → |
| 3 g | Oral | Kesin Pharma Corporation | ANDA | View NDC → |
Showing 9 of 9 products — FDA National Drug Code Directory. See every product, package size and price: browse all 9 Fosfomycin NDCs →
Fosfomycin side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Fosfomycin — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Fosfomycin in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Fosfomycin FDA approval history
How Fosfomycin went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Fosfomycin recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list 2 Fosfomycin recalls since July 2021. One of them is still ongoing and is listed first. A recall names specific lots from one company, so check the lot number on your own bottle rather than assuming every product is affected; your pharmacist can check whether your supply came from an affected lot.
- Fosfomycin Tromethamine Granules for Oral Solution, (equivalent to 3 grams of fosfomycin), single-dose sachet, Rx Only, Manufactured by: Alkem Laboratories Ltd., INDIA. Distributed by: Ascend Laborat… Lots: lOTS #: 22121458, 22121459, 22121460, 22121461, 22121462, 22121463, 22121464, Exp 4/2024; 22121176, 22121407, 22121465, Exp 3/2024; 22121761, 22121762, 22121763, 22121764, 22121766, 22121968, 22121969, Exp 5/2024. FDA record D-0339-2024 →
- Fosfomycin Tromethamine Granules for Oral Solution, 3 g single- dose sachet, Rx only, Manufactured by: Alkem Laboratories Ltd., INDIA, Distributed by: Ascend Laboratories, LLC, Parsippany, NJ 07054,… Lots: Lot #22121970, 22122158, 22121971, 22122189, 22122190, 22122277, 22122278, Exp June 2024; 22122521, 22122522, 22122523, Exp July 2024; 22123328, 22123329, 22123330, Exp September 2024. FDA record D-1145-2023 →
Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 4550 2 dose forms · 2 strengths
Look up RxCUI 4550 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Fosfomycin supply and shortage status
Whether Fosfomycin is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
💵 What Fosfomycin costs pharmacies (NADAC benchmark)
The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.
| Form | Strength | Pharmacy acquisition benchmark | |
|---|---|---|---|
| Granule · Oral | 3 g | $26.22 each | NDC details & price history |
Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.
Fosfomycin brand names
Fosfomycin is sold under 2 brand names in the FDA directory — Monurol Sachet, Contepo. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Fosfomycin: manufacturers and labelers
9 companies list Fosfomycin products with the FDA. By number of product records, the largest are A-S Medication Solutions, Amneal Pharmaceuticals NY LLC, Ascend Laboratories, LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Fosfomycin drug class (RxNorm)
Fosfomycin belongs to the Other antibacterials class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Fosfomycin page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Aucta Pharmaceuticals, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →