ATC Code J01XX01
Formula C3H7O4P
Molar Mass (g·mol−1) 138,059
Physical State solid
Density (g·cm−3) 1,6
Melting Point (°C) 94
Boiling Point (°C) 342
CAS Number 23155-02-4
PUB Number 446987
Drugbank ID DB00828
Solubility soluble in water


Fosfomycin is the first and so far the only representative of the epoxide antibiotics group and thus has a unique mechanism of action. It is particularly effective against many Gram-negative bacteria. It is used for uncomplicated urinary tract infections, where only one dose is required. Otherwise, it is used more cautiously and in severe infections such as inflammation of the meninges, bone marrow or lungs.



Fosfomycin blocks murein synthesis and thus cell wall construction of bacteria by inhibiting a specific enzyme. In the case of cystitis, it should be taken in the evening and water should be avoided until the next morning to allow the antibiotic to exert its full effect.


Oral bioavailability is 32 to 54%, intravenous administration is also possible. The effect usually lasts for more than 36 hours. Since it is excreted by the kidneys, dose reduction is required in cases of reduced renal function.

Drug interactions

Synergistic effects may be achieved in combination with beta-lactam antibiotics, such as penicillins, cephalosporins, and carbapenems. Parallel medication with metoclopramide may reduce efficacy, so an interval of at least two to three hours should be maintained. In addition, the effect of vitamin K antagonists (e.g., Marcumar) is increased when fosfomycin is taken, which may lead to increased bleeding.


Side effects

Overall, this epoxide antibiotic is well tolerated. However, in addition to common side effects such as headache, dizziness, nausea, and vomiting, elevation of liver enzymes, sensory disturbances, or reduction of white blood cells or platelets may rarely occur.

Toxicological data

Animal studies in rats also showed good tolerance of the antibiotic with a median lethal dose of over 10 g/kg body weight, and no evidence of adverse effects in pregnancy was seen.

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Markus Falkenstätter

Markus Falkenstätter

Markus Falkenstätter is a writer on pharmaceutical topics in Medikamio's medical editorial team. He is in the last semester of his pharmacy studies at the University of Vienna and loves scientific work in the field of natural sciences.

Mag. pharm Stefanie Lehenauer

Mag. pharm Stefanie Lehenauer

Stefanie Lehenauer has been a freelance writer for Medikamio since 2020 and studied pharmacy at the University of Vienna. She works as a pharmacist in Vienna and her passion is herbal medicines and their effects.

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