fosfomycin at a glance
Medicine class
Bactericidal antibiotic for systemic use
Important practical point
The intravenous product has a high sodium content, so fluid balance and electrolytes may require monitoring
What is fosfomycin used for?
Intravenous fosfomycin is licensed for all age groups when antibiotics commonly used first are considered inappropriate.
Complicated urinary tract infections
Infective endocarditis
Bone and joint infections
Hospital-acquired pneumonia, including ventilator-associated pneumonia
Complicated skin and soft-tissue infections
Bacterial meningitis
Complicated intra-abdominal infections
Bacteraemia associated with, or suspected to be associated with, these infections
How does fosfomycin work?
Fosfomycin enters bacterial cells and blocks an early step in making peptidoglycan, an essential part of the cell wall. Growing susceptible bacteria consequently lose cell-wall integrity and die.
fosfomycin preparations and strengths
Solution for infusion
Route: Intravenous
Strengths: 40 mg/mL
How to take fosfomycin
The selected product is administered into a vein by a healthcare professional; food does not affect its administration.
The powder must be reconstituted and further diluted before infusion.
It must not be administered into an artery.
Sodium chloride solutions must not be used to prepare this product.
fosfomycin side effects
Common or expected effects
- Altered taste
- Red skin eruption
- Inflammation or discomfort at the infusion site
- Changes in sodium or potassium levels
Get urgent medical advice
- Severe allergic reaction, including anaphylaxis
- Severe or persistent antibiotic-associated diarrhoea or colitis
- Low white-cell or platelet counts
- Severe sodium or potassium disturbance, potentially causing confusion, seizures, weakness or abnormal heart rhythm
- Angioedema or severe widespread skin reaction
- Hepatitis
fosfomycin in pregnancy
Intravenous fosfomycin crosses the placenta, and direct pregnancy data are lacking. It should be used during pregnancy only after the prescriber decides that the expected benefit outweighs the potential risk.
fosfomycin while breastfeeding
Small amounts enter breast milk, but evidence is limited. Intravenous fosfomycin is not considered a first choice while breastfeeding, particularly for a premature or newborn infant; an individual assessment should consider the infection, alternatives and infant monitoring.
fosfomycin interactions
Interaction evidence for intravenous fosfomycin is limited, but infection and antibiotic treatment can affect anticoagulation control.
Oral anticoagulants, such as warfarin
Anticoagulant activity and INR may increase or become unstable, so closer INR assessment may be required.
Common questions about fosfomycin
Answers are fully visible for fast scanning and source review.
Why is intravenous fosfomycin usually reserved for difficult infections?
Its UK licence positions it for specified serious or complicated infections when antibiotics commonly used first are inappropriate. Clinical data are limited for some indications, and resistance can emerge during treatment.
Is fosfomycin a penicillin?
No. Fosfomycin is a distinct antibacterial class that blocks an earlier stage of bacterial cell-wall synthesis.
Does fosfomycin treat viral infections?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.