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Phosphonic Acid Antibiotic (Uncomplicated UTI / MDR UTI)

Fosfomycin

Brand names: Monurol (oral granules), Fomicyt (IV)

Used in: Urinary Tract Infection

Fosfomycin is given as a single oral dose (sachet) for uncomplicated lower urinary tract infection, and is useful against some multidrug-resistant organisms.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE & 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 …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-09-25. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It inhibits an early step in bacterial cell-wall synthesis, and is concentrated in the urinary tract after oral administration.

Prescribing in practice

  • Reserve for uncomplicated lower urinary tract infection per stewardship, particularly to preserve activity against resistant organisms.
  • It is generally well tolerated, with gastrointestinal upset being the most common adverse effect.
  • It is taken as a single oral dose, which supports adherence in uncomplicated infection.

Monitoring

Routine monitoring is not usually required; reassess if symptoms persist or recur and review against urine culture and sensitivities.

Counselling the patient

  • Dissolve the sachet in water and take the single dose as directed, ideally on an empty stomach.
  • Seek further advice if urinary symptoms do not improve or come back.

Evidence & guidelines

A useful single-dose option for uncomplicated lower urinary tract infection, including some resistant organisms; use per local antimicrobial guidance.

Reference: NICE 2022 Urinary Tract Infections Guidelines; EAU UTI Guidelines 2023; MHRA SPC Fomicyt/Monurol; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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