Fosfomycin

Pronunciation: fos-foh-MY-sin.

Generic name
fosfomycin
Drug class
Broad-spectrum bactericidal antibiotic (a phosphonic acid derivative, structurally unrelated to other antibiotic classes)
Form
Granules for oral solution, single-dose sachet (Monurol/Monuril/UroFos, depending on market); powder for solution for infusion, intravenous (Contepo, US; Fomicyt, UK/EU)
Route
Oral (as fosfomycin tromethamine) or intravenous infusion (as fosfomycin disodium/fosfomycin sodium), depending on the specific formulation and clinical purpose
Legal status
Prescription-only medicine in all markets reviewed

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Monurol (oral, single-dose sachet) (7), Pharmacor Fosfomycin (generic, oral) (7) · Full directory

What fosfomycin is and how it works

Fosfomycin is a broad-spectrum antibiotic used in two genuinely different ways depending on the formulation: as a single oral dose for uncomplicated urinary tract infection (cystitis) in women, and as an intravenous treatment for more serious, complicated urinary tract infections, including kidney infection (pyelonephritis), when other antibiotics are unsuitable. It works by blocking an early step in bacterial cell-wall formation. (1) (2)

No boxed warning applies to fosfomycin in either formulation, which is a genuinely reassuring, verified finding rather than an oversight. The oral, single-dose form used for cystitis is generally well tolerated, with its main real risks being antibiotic-associated diarrhoea (including, rarely, C. difficile infection) and a reduction in effectiveness if taken together with metoclopramide or similar medicines. The intravenous form, used for more serious infections, carries additional real risks related to its high sodium content, including changes in blood electrolyte levels, and requires monitoring by the treating medical team.

Mechanism of action: how fosfomycin works

Fosfomycin is a phosphonic acid derivative, structurally unrelated to other antibiotic classes, that inhibits an early step in bacterial peptidoglycan (cell wall) synthesis by irreversibly inactivating the enzyme MurA (enolpyruvyl transferase), giving it bactericidal activity against a broad range of gram-negative and some gram-positive organisms. (2) (6)

What fosfomycin is used for

Uncomplicated urinary tract infection (cystitis) in women -- oral, single dose

The oral formulation (Monurol/Monuril/UroFos, depending on market) is used as a single 3 g dose to treat uncomplicated urinary tract infection (acute cystitis) caused by susceptible bacteria, in women (and, in some markets, female adolescents over 12). It is not indicated for kidney infection (pyelonephritis) or infections that have spread beyond the bladder. In the UK, it is also used as a single-dose antibiotic given before and after a transrectal prostate biopsy in men, to reduce infection risk. (1) (3)

Complicated urinary tract infection, including kidney infection -- intravenous

The intravenous formulation is used in hospital for complicated urinary tract infections, including acute pyelonephritis (kidney infection), in adults, when the infection is more serious or has not responded to other treatment. In the European Union, its use is specifically restricted to serious infections when other antibiotic treatments are not suitable, reflecting a real, formulation-specific regulatory decision distinct from the oral formulation's routine use for cystitis. (2) (5)

Before taking fosfomycin

Do not take / not appropriate for

  • Do not take fosfomycin if you have a known allergy or serious hypersensitivity to fosfomycin or any of its ingredients. (all countries) (1) (3)
  • Oral fosfomycin is not recommended if you have severe kidney impairment (creatinine clearance below 10 mL/min) -- confirmed in the UK source reviewed. (United Kingdom) (3)
  • Oral fosfomycin is not established as safe and effective in children 12 years and under, and is not recommended for anyone under 18 in the US source reviewed. (United States) (1)

Tell your clinician about

  • Any known allergies to antibiotics.
  • Any kidney problems.
  • Whether you are pregnant, plan to become pregnant, or are breastfeeding.
  • All other medicines you take, especially metoclopramide or other medicines that increase gut motility.
  • For the intravenous formulation: any heart problems, high blood pressure, or conditions affecting your body's salt (sodium) or potassium balance.
(1) (3) (2)

How to take fosfomycin

  • Oral formulation: dissolve the entire contents of one sachet in a small glass of water (not hot water) and drink immediately -- do not take it dry.
  • Take the oral dose on an empty stomach where possible, ideally 2-3 hours before or after a meal, ideally at bedtime after emptying your bladder, since this may improve how well it works, though it can be taken with or without food if needed.
  • Oral fosfomycin is a single-dose treatment -- do not take repeated daily doses; if your symptoms do not improve, contact your prescriber rather than taking another dose yourself.
  • The intravenous formulation is given only by a healthcare professional in a hospital or clinical setting, with the dose and frequency individualised to your kidney function.
(1) (3) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6) (7) (8)

Missed dose

Oral fosfomycin is a single-dose treatment, so a 'missed dose' does not usually apply in the same way as with regular medicines -- if you did not take it as directed, or your symptoms have not improved, contact your prescriber rather than taking another dose yourself.

Overdose

Seek medical advice or emergency help if you think you have taken more than the prescribed single dose, or if you experience severe symptoms. Overdose management is symptomatic and supportive, with monitoring of blood salt (electrolyte) levels and encouragement of fluid intake to help the kidneys clear the medicine. (6)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Diarrhoea.

What to notice: Diarrhoea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (3)

Nausea.

What to notice: Nausea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (3)

Headache.

What to notice: Headache.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (3)

Vaginal inflammation (vaginitis).

What to notice: Vaginal inflammation (vaginitis).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (3)

For the intravenous formulation: changes in blood test results affecting the liver, low potassium levels, and a reduced white blood cell count (neutropenia) have occurred more often than with a comparator antibiotic in the trial reviewed.

What to notice: For the intravenous formulation: changes in blood test results affecting the liver, low potassium levels, and a reduced white blood cell count (neutropenia) have occurred more often than with a comparator antibiotic in the trial reviewed.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (2)

Serious warnings

Clostridioides difficile-associated diarrhoea (CDAD) — high caution

Symptoms: Watery or bloody diarrhoea, abdominal pain or cramping, and fever, which can appear up to two months after finishing treatment.

Action: Contact your prescriber promptly if this occurs, even after you have finished your dose -- do not treat diarrhoea with anti-diarrhoeal medicines yourself without checking with your prescriber first, since this class of antibiotic-associated diarrhoea needs proper assessment. (1) (3)

Serious allergic reaction (anaphylaxis) — emergency

Symptoms: Swelling of the face, lips, or throat, difficulty breathing, widespread rash, or feeling faint.

Action: Seek emergency medical help immediately. This has been reported rarely after fosfomycin, even though it is not chemically related to penicillin-type antibiotics. (1)

Electrolyte disturbances from the intravenous formulation's sodium content — high caution

Symptoms: Muscle weakness, irregular heartbeat, confusion, or swelling -- signs of low potassium, low calcium, low phosphate, or high sodium levels.

Action: This risk applies only to the intravenous formulation, given in hospital, where your treating team will monitor your blood salt levels during treatment. Tell your care team about any heart problems, high blood pressure, or salt-balance conditions beforehand. (2)

Liver enzyme changes and reduced white blood cell count (intravenous formulation) — high caution

Symptoms: Not always noticeable to the patient -- usually detected through blood tests ordered by the treating team; may include unusual tiredness, yellowing of the skin or eyes, or increased infections.

Action: Your treating team will monitor liver function and blood counts during intravenous treatment. (2)

Interactions

  • Metoclopramide (and other medicines that increase gut motility): can lower the amount of oral fosfomycin absorbed into the blood and passed into the urine, reducing its effectiveness -- this combination should be avoided. (1) (3)
  • Food: may delay absorption of oral fosfomycin and reduce peak drug levels; taking it on an empty stomach is preferred, though it can be taken with food if needed. (3)
  • Cimetidine: no significant interaction found with oral fosfomycin in the US source reviewed. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Oral fosfomycin should be used in pregnancy only if clearly necessary; limited first-trimester safety data reviewed (152 pregnancies) showed no signal of a specific risk to the developing baby, but data remain limited. Always discuss the risks and benefits with your prescriber. (1) (2) (3) (4) (5) (6) (7) (8)

Breastfeeding

A single dose of oral fosfomycin may be used while breastfeeding if clearly necessary, since only low amounts pass into breast milk, per the UK source reviewed. (1) (2) (3) (4) (5) (6) (7) (8)

Children

Oral fosfomycin's safety and effectiveness have not been established in children 12 years and under; it is not recommended in the US for anyone under 18. In the UK, it may be used in female adolescents over 12 for cystitis specifically. (1) (2) (3) (4) (5) (6) (7) (8)

Elderly

Specific dose adjustment guidance for older adults was not detailed in the sources reviewed beyond the standard single dose for the oral formulation; kidney function should be considered, as for any antibiotic. (1) (2) (3) (4) (5) (6) (7) (8)

Hepatic Impairment

Specific dose guidance was not detailed in the sources reviewed for liver impairment; your prescriber will assess this individually, and the intravenous formulation includes monitoring for liver enzyme changes. (1) (2) (3) (4) (5) (6) (7) (8)

Renal Impairment

Oral fosfomycin is not recommended if your creatinine clearance is below 10 mL/min, per the UK source reviewed. The intravenous formulation has a specific renal-function-based dosing schedule, with dose and frequency adjusted according to kidney function. (1) (2) (3) (4) (5) (6) (7) (8)

Monitoring

Before starting

  • Assessment of kidney function, especially before intravenous treatment or if kidney impairment is suspected
  • Review of other medicines, especially metoclopramide or similar medicines, before the oral dose

During treatment

  • For the intravenous formulation: monitoring of blood electrolyte levels (sodium, potassium, calcium, phosphate), liver function tests, and blood counts during treatment.
  • Watch for diarrhoea during and for up to two months after treatment, and report it to your prescriber if it occurs.
(2) (1)

Storage

Store the oral sachet at room temperature, away from moisture, out of reach of children. Dissolve only when ready to take. The intravenous formulation is stored, prepared, and administered by hospital staff.

Study the drug class: Fosfomycin

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information (Monurol, oral; Contepo, IV), the UK emc SmPC (Monuril, oral; Fomicyt, IV), and the EMA's 2020 Article 31 referral outcome reviewed for this dossier; verify against the current full label before prescribing.

United States

Indication: Uncomplicated cystitis in women (Monurol, oral); complicated UTI/acute pyelonephritis in adults (Contepo, IV, approved October 2025)

Dose summary: Monurol: single 3 g oral dose. Contepo: 6 g IV loading dose, then a maintenance dose (3-5 g) and frequency (every 8-24 hours) adjusted by creatinine clearance band; haemodialysis patients dosed post-dialysis.

Renal context: Monurol not studied specifically by renal band in the source reviewed. Contepo has an explicit renal-function-based dosing table from >50 mL/min down to 11-20 mL/min creatinine clearance. (1) (2)

United Kingdom / European Union

Indication: Uncomplicated cystitis and prostate-biopsy prophylaxis (oral); serious infections when other antibiotics are unsuitable (IV, EU-restricted since 2020)

Dose summary: Monuril: single 3 g oral dose for cystitis; 3 g pre-procedure plus 3 g at 24 hours for prostate-biopsy prophylaxis. Fomicyt (IV): dosing not detailed in the sources reviewed for this pass.

Renal context: Oral fosfomycin not recommended if creatinine clearance <10 mL/min, per the UK SmPC reviewed. (3) (5)

Mechanism of action

Hepatic guidance

The intravenous formulation is associated with a higher rate of transaminase elevation than a comparator antibiotic in the pivotal trial reviewed; monitor hepatic function during IV treatment.

Overdose note

Manage overdose with supportive care and monitoring of plasma/serum electrolytes; urinary elimination can be encouraged with adequate oral fluid intake. (2) (6)

Frequently asked questions

Is fosfomycin available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, the oral formulation is authorised and marketed in all six regions reviewed, though under different brand names: the United States and Canada (Monurol), the United Kingdom and much of the European Union (Monuril, plus other nationally authorised brands), Australia (Monurol and a generic, Pharmacor Fosfomycin), and New Zealand (UroFos -- a genuinely different brand name from the others). An intravenous formulation is also confirmed in the United States (Contepo, newly approved in October 2025) and the United Kingdom/European Union (e.g. Fomicyt in the UK); its specific availability in Canada, Australia, and New Zealand could not be confirmed in this research pass. (1) (3) (6) (7) (8) (2)

Does fosfomycin have a boxed warning like some other antibiotics?

No. This was directly checked against the current US FDA labels for both the oral formulation (Monurol) and the intravenous formulation (Contepo), and neither carries a boxed warning. Fosfomycin still has real warnings to be aware of -- including antibiotic-associated diarrhoea for the oral form, and sodium/electrolyte-related effects for the intravenous form -- but neither rises to the level of the FDA's strongest warning category. (1) (2)

Why is intravenous fosfomycin restricted in the European Union?

Following a European Union-wide safety review completed in 2020, intravenous fosfomycin was restricted to treating serious infections when other antibiotic treatments are not suitable. This restriction applies only to the intravenous formulation -- oral fosfomycin for uncomplicated bladder infections (cystitis) was not affected and can still be used as before. (5)

Can I take fosfomycin with other medicines?

Most medicines do not seriously interact with oral fosfomycin, but metoclopramide (and similar medicines that speed up stomach emptying) can reduce how much fosfomycin your body absorbs, making it less effective -- this combination should be avoided. Always tell your prescriber about all the medicines you take. (1) (3)

What is the mechanism of action of fosfomycin?

Fosfomycin is a phosphonic acid derivative, structurally unrelated to other antibiotic classes, that inhibits an early step in bacterial peptidoglycan (cell wall) synthesis by irreversibly inactivating the enzyme MurA (enolpyruvyl transferase), giving it bactericidal activity against a broad range of gram-negative and some gram-positive organisms. (2) (6)

What is the generic name of Fosfomycin?

The generic name is fosfomycin. (1) (2)

What class of drug is fosfomycin?

Fosfomycin is classed as: Broad-spectrum bactericidal antibiotic (a phosphonic acid derivative, structurally unrelated to other antibiotic classes). (1) (2)

References

  1. MONUROL (fosfomycin tromethamine) granules for oral solution -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · dated 2018-01-01 · accessed 2026-07-30 · source 1
  2. CONTEPO (fosfomycin disodium) injection, powder for solution, for intravenous use -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · dated 2025-10-22 · accessed 2026-07-30 · source 2
  3. Monuril 3g granules for oral solution (fosfomycin trometamol) -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics (SmPC) · United Kingdom · dated 2025-01-01 · accessed 2026-07-30 · source 3
  4. Fomicyt 40 mg/ml powder for solution for infusion (fosfomycin) -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom -- Summary of Product Characteristics (SmPC) · United Kingdom · dated 2020-01-01 · accessed 2026-07-30 · source 4
  5. Fosfomycin-containing medicinal products -- Article 31 referral, CHMP opinion and European Commission decisionEuropean Medicines Agency (EMA) / European Commission -- Article 31 referral outcome · European Union · dated 2020-06-09 · accessed 2026-07-30 · source 5
  6. MONUROL (fosfomycin tromethamine) powder for oral solution -- Product MonographHealth Canada -- Product Monograph · Canada · dated 2026-01-01 · accessed 2026-07-30 · source 6
  7. MONUROL fosfomycin (as trometamol) 3 g granules for oral solution -- ARTG entry and AusPARTherapeutic Goods Administration (TGA), Australia -- Australian Register of Therapeutic Goods (ARTG); Australian Public Assessment Report (AusPAR) · Australia · dated 2017-09-04 · accessed 2026-07-30 · source 7
  8. UroFos (fosfomycin trometamol) granules for oral solution -- New Zealand Data SheetMedsafe (New Zealand Medicines and Medical Devices Safety Authority) -- New Zealand Data Sheet · New Zealand · dated 2020-06-01 · accessed 2026-07-30 · source 8

Brand names by country

Single-ingredient fosfomycin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Contepo6 g · meitheal pharmaceuticals inc.

United Kingdom

  • Monuril (oral, single-dose sachet) (3)emc current smpc confirmed · 3 g fosfomycin · Advanz Pharma
  • Fomicyt (intravenous) (4)emc current smpc confirmed · 40 mg/mL · InfectoPharm

Canada

  • MONUROL

Australia

  • Monurol (oral, single-dose sachet) (7)tga artg registered confirmed · 3 g fosfomycin (as trometamol) · Mayne Pharma International Pty Ltd
  • Pharmacor Fosfomycin (generic, oral) (7)tga artg registered confirmed · 3 g fosfomycin (as trometamol) · Pharmacor Pty Ltd

New Zealand

  • UroFos (oral, single-dose sachet) (8)medsafe data sheet confirmed · 3 g fosfomycin (as trometamol) · Confirmed via Medsafe data sheet
View brands in additional countries.

European Union

Oral fosfomycin (various nationally authorised brands) (5), Intravenous fosfomycin (various nationally authorised brands, e.g. Fomicyt) (5)

This page provides general reference information about fosfomycin and is not a substitute for advice from the prescriber managing your care. All dosing and treatment decisions, including starting, changing, or stopping this medicine, should be made with your prescriber.

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