In the U.S.—

• Antibacterial, systemic

Fosfomycin ( fos-foe-MYE-sin) is an antibiotic. It is used to treat urinary tract infection and cystitis (bladder infection) in women.

This medicine is available only with your doctor's prescription, in the following dosage form:

Oral
• Powder for solution (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For fosfomycin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to fosfomycin. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Fosfomycin has not been studied in pregnant women. However, it does pass through the placenta from the mother to the baby. In animals, fosfomycin has been shown to cause some harmful effects in the mother and the infant.

Breast-feeding—It is not known whether fosfomycin passes into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who receive this medicine and who wish to breast-feed should discuss this with their doctor.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even in an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your doctor and pharmacist if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

• Kidney disease—Effects of fosfomycin may be increased because of slower removal from the body

Fosfomycin powder must be dissolved in water before it is taken. Take the medicine as soon as it has dissolved.

This medicine can be taken with or without food.

Dosing—

The dose of fosfomycin may be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of fosfomycin. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (powder for solution):
  • For treatment of bladder infection:
    • Adults—3 grams (one packet) dissolved in water taken one time.
    • Children—Use and dose must be determined by your doctor.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Check with your doctor if your symptoms do not improve within 2 or 3 days or if they become worse.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Vaginal discharge and pain 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Diarrhea;  headache;  nausea 
  
  

• Less common
  • Abdominal or stomach pain;  back pain ;  dizziness;  heartburn;  indigestion;  pain;  painful menstruation;  runny or stuffy nose;  skin rash;  sore throat;  weakness 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.