How does this medication work? What will it do for me?

Fosfomycin belongs to the class of medications called antibiotics. It is used  by adult women to treat uncomplicated bladder infections caused by certain bacteria.

Fosfomycin works by killing the bacteria that cause the infection.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each sachet of powder contains 5.63 g of fosfomycin tromethamine, equivalent to 3 g of fosfomycin. Nonmedicinal ingredients: mandarin and orange flavouring, saccharin and sucrose.

How should I use this medication?

Fosfomycin is taken by mouth as a single dose. The contents of a single sachet should be added to a glass containing 125 mL (1/2 cup) of cold water. Stir to dissolve the powder completely, then immediately drink the solution containing the medication.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Fosfomycin may be taken with food or on an empty stomach, but separated from other medications.

It is important that this medication be taken exactly as prescribed by your doctor. You should notice improvement in your symptoms within 2 to 3 days. If your symptoms do not improve by the fourth day, you should contact your doctor.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you are allergic to fosfomycin or any ingredients of the medication.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain
  • diarrhea
  • dizziness
  • headache
  • heartburn
  • nausea

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

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

  • rash
  • vaginal itching
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Antibiotic-associated colitis: This medication, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated, or pseudomembranous, colitis. Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, contact your doctor as soon as possible.

Overgrowth of organisms: Prolonged or repeated use of antibiotics may result in an overgrowth of bacteria or fungi and organisms that are not killed by the medication. This can cause other infections, such as yeast infections, to develop.

Pregnancy: Fosfomycin crosses the placenta and may affect a developing baby if it is taken during pregnancy. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if fosfomycin passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between fosfomycin and any of the following:

  • BCG vaccine
  • metoclopramide
  • probenecid
  • sodium picosulfate
  • typhoid vaccine

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.