Fosfomycin, or fosfomycin trometamol, is an antibiotic that is often prescribed for urinary tract infections, like acute or recurrent cystitis and urethritis. It can also be prescribed when bacteria is detected in the urine during pregnancy even if the mother does not present with infectious symptoms.

Fosfomycin can also be prescribed to prevent urinary infections after surgery, as it works by eliminating bacteria from the urinary tract. It is particularly effective against staphylococci, streptococci, E.coli, Proteus sp., Klebsiella sp., Enterobacter sp. and Citrobacter sp bacteria.

This medicine can be found in pharmacies or drugstores in the form of a 3 g sachet. In the United States, it is mainly available as generic fosfomycin tromethamine, equivalent to the original brand Monurol. It can be obtained with a prescription.

What is it used for?

Fosfomycin is mainly prescribed to treat urinary tract infections, as it is effective against several types of bacteria. It can also be indicated for cases where bacteria are found in the urine during pregnancy, even when there are no symptoms of infection.

The main situations where fosfomycin may be used include:

Acute or recurrent cystitis
Acute bacterial urethrovesical syndrome
Urethritis
Bacteria in urine during pregnancy
Urinary tract infections after surgery

In addition, doctors may prescribe fosfomycin to prevent urinary infections after surgical procedures or diagnostic exams such as cystoscopy or cystourethrography.

How to take

Fosfomycin tromethamine (generic equivalent to Monurol) should be dissolved in a glass of water (50 to 75 mL) and mixed with a spoon. The solution should be taken on an empty stomach immediately after preparation, preferably at night before going to bed and after urinating.

Standard dosing – uncomplicated UTI

1 sachet (3 g), taken as a single oral dose

Extended dosing – complicated or recurrent infections

1 sachet (3 g), repeated every 48 to 72 hours for 2–3 doses (e.g., on days 1, 3, and 5)

Prevention of urinary infections before or after surgery

1 sachet (3 g), taken 3 hours before the procedure
1 sachet (3 g), taken 24 hours after the procedure

After starting treatment, symptoms are expected to improve within 2 to 3 days. If there is no improvement, medical reassessment is recommended.

Check out home remedies for UTIs that you can prepare to complement the medical treatment prescribed by your doctor.

Possible side effects

Some of the side effects that may occur during treatment with fosfomycin are headache, dizziness, vaginal infections, nausea, stomach pain, diarrhea, or skin reactions including itching and redness.

Contraindications for use

Fosfomycin should not be used by anyone who is allergic to fosfomycin or any of the components in the formula. Furthermore, it should also not be used by anyone undergoing hemodialysis, children under 12 years of age, or in cases of severe kidney failure.

Fosfomycin during pregnancy or breastfeeding should only be used as per medical advice and guidance.

Fosfomycin: Uses, How to Take, Side Effects & Contraindications