Adult

Fosfomycin

General Information

Phosphonic acid derivative antibacterial

Restricted formulary antimicrobial: For details see OUH netFormulary

Oral: AWaRe antibiotic classification: 'Access'. Use as per guidelines. 

IV: AWaRe antibiotic classification: 'Reserve'. All indications to be discussed with Micro/ID.

For all information regarding contra-indications, interactions, contraception, pregnancy and breastfeeding and additional information, see BNF and Summary of Product Characteristics (SPC).

Dosing

  Oral treatment dose IV* treatment dose
Uncomplicated lower UTI 3g once only  
Difficult-to-treat resistance Pseudomonas aeruginosa (DTR-PSAR) infection   12g - 24g in 2-3 divided doses (max. per dose 8g)

For other indications, discuss dosing with Micro/ID.

*Elderly patients - Caution is advised when considering the use of IV doses at the higher end of the recommended range.

Obesity

IV fosfomycin: use the higher end of the dosing range.

Renal and hepatic impairment

Renal impairment  

Creatinine Clearance 

(ml/min)**

 Oral treatment dose IV treatment dose
Over 80 Dose as in normal renal function

Dose as in normal renal function
40-80 Dose as in normal renal function

Dose as in normal renal function

Use with caution, particularly if doses at higher end of the recommended range.
31 upto 40 Dose as in normal renal function

Normal loading dose for 1st dose (must not exceed 8g),

then 70% of normal daily dose in 2-3 divided doses
21-30 Dose as in normal renal function

Normal loading dose for 1st dose (must not exceed 8g),

then 60% of normal daily dose in 2-3 divided doses
11-20 Dose as in normal renal function

Normal loading dose for 1st dose (must not exceed 8g),

then 40% of normal daily dose in 2-3 divided doses
Less than 10 Avoid

Normal loading dose for 1st dose (must not exceed 8g),

then 20% of normal daily dose in 1-2 divided doses
HD/HDF/High Flux Avoid

DIalysed.

2g - 4g post-dialysis
PD Avoid

Dialysed.

Dose as in CrCl less than 10mL/min.

 **dose ranges use creatinine clearance, rather than eGFR

Note: Doses are based on Renal Drug Database

 

Hepatic impairment

No dose adjustment required.

References

  1. InfectoPharm Ltd. Fomicyt 40 mg/ml powder for solution for infusion summary of product characteristics. Electronic medicines compendium. Last revision of the text 14/8/24. Accessed via www.medicines.org.uk Accessed 13/10/26.
  2. Zambon UK Limited. Monuril 3g granules for oral solution summary of product characteristics. Electronic medicines compendium. Last revision of the text 17/5/21. Accessed via www.medicines.org.uk Accessed 13/10/26.
  3. The Renal Drug Database. Fosfomycin. Last updated 6/11/24. Accessed via https://renaldrugdatabase.com Accessed 13/10/26.
  4. British National Formulary. Fosfomycin. BNF online accessed via www.medicinescomplete.com  Accessed 13/10/26.
  5. All-Wales Antimicrobial Pharmacists’ Group (2022) Antimicrobial dosing in extremes of body weight in adults. Accessed 13/10/26.
  6. Sanford Guide [online] Fosfomycin disodium. Last updated 23/6/26. Accessed via: https://webedition.sanfordguide.com Accessed 13/10/26.
  7. Sanford Guide [online] Fosfomycin tromethamine. Last updated 16/9/26. Accessed via: https://webedition.sanfordguide.com Accessed 13/10/26.

Editorial Information

Last reviewed: 13 Oct 2026

Next review date: 11 Oct 2029

Author(s): AMST.