Classifications: antibiotic;
Therapeutic: antibiotic
; urinary tract antiinfective
Prototype: Nitrofurantoin
Pregnancy Category: B


3 g packets


Synthetic, broad-spectrum, bactericidal antibiotic active against gram-negative and gram-positive aerobic organisms that blocks the first steps in bacterial cell wall synthesis.

Therapeutic Effect

Acts as a bactericidal agent against Enterococcus faecalis, E. faecium, and Escherichia coli. In addition, it is effective against Klebsiella, Proteus, and Serratia. Indicated by improvement in cystitis symptoms within 2–3 d.


Treatment of uncomplicated UTIs in women due to susceptible strains of E. coli and E. faecalis.


Hypersensitivity to fosfomycin.

Cautious Use

Pregnancy (category B); lactation. Safety and efficiency in children <12 y are not established.

Route & Dosage

Adult: PO 3 g sachet dissolved in 3–4 oz of water as a single dose given once


  • Pour entire contents of a single dose into 3–4 oz water (not hot), stir to dissolve completely, and give immediately. Drug must not be taken in the dry form.
  • Store at 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

Body as a Whole: Pain. CNS: Headache, dizziness. GI: Diarrhea, nausea, abdominal pain, dyspepsia. Respiratory: Rhinitis, pharyngitis. Urogenital: Vaginitis, dysmenorrhea.


Drug: Metoclopramide may decrease urinary excretion of fosfomycin.


Absorption: Rapidly from GI tract, 37% of dose reaches systemic circulation as free acid. Peak Urine Concentration: 2–4 h. Distribution: Not protein bound, distributed to kidneys, bladder wall, prostate, and seminal vesicles. Elimination: Primarily in urine. Half-Life: 5.7 h.

Nursing Implications

Assessment & Drug Effects

  • Lab tests: Obtain urine C&S before and after therapy.

Patient & Family Education

  • Notify physician if symptoms do not improve in 2–3 d.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2023 Last Updated On: 01/29/2023 (0)
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