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Why is this medication prescribed?

Fosfomycin is an antibiotic medication that is primarily prescribed to treat urinary tract infections (UTIs) caused by susceptible bacteria. It is often used as a first-line treatment for uncomplicated UTIs, particularly those caused by Escherichia coli (E. coli) bacteria. Fosfomycin works by interfering with bacterial cell wall synthesis, ultimately leading to bacterial cell death.

How should this medicine be used?

When using fosfomycin, it’s essential to follow your healthcare provider’s instructions and the dosage prescribed on the medication label. Typically, fosfomycin is available as a powder for oral suspension or in sachets containing granules for oral solution. It’s crucial to mix the powder or granules with water before consumption.

The usual dosage for fosfomycin in adults for the treatment of uncomplicated UTIs is a single dose of 3 grams taken orally. For more severe infections or those caused by bacteria that are less susceptible to fosfomycin, your healthcare provider may prescribe a different dosage regimen.

It’s important to take the full course of fosfomycin as prescribed, even if your symptoms improve before you’ve finished the medication. This helps to ensure that the infection is completely eradicated and reduces the risk of antibiotic resistance.

If you have any questions or concerns about how to use fosfomycin or its potential side effects, it’s essential to consult your healthcare provider or pharmacist for guidance.

Other uses for this medicine

Some potential off-label uses of fosfomycin include:

  • Treatment of other bacterial infections: Fosfomycin may be used in the treatment of certain bacterial infections other than UTIs, although its efficacy in these cases may vary.
  • Prophylaxis in certain surgical procedures: Fosfomycin might be used as prophylaxis to prevent postoperative infections in specific surgical procedures, especially in situations where there is a high risk of infection and where other antibiotics may not be suitable.

What special precautions should I follow?

As for special precautions when using fosfomycin, here are some key points to keep in mind:

  • Allergies: Inform your healthcare provider if you have any allergies, particularly to fosfomycin or other antibiotics. This medication should be used with caution if you have a history of allergic reactions to antibiotics.
  • Pregnancy and breastfeeding: If you are pregnant or breastfeeding, it’s essential to discuss the risks and benefits of using fosfomycin with your healthcare provider. They can help determine whether the benefits outweigh the potential risks to you and your baby.
  • Kidney function: Fosfomycin is primarily excreted through the kidneys, so dosage adjustments may be necessary in individuals with impaired kidney function. Your healthcare provider will determine the appropriate dosage based on your kidney function.
  • Drug interactions: Inform your healthcare provider about all the medications you are currently taking, including prescription, over-the-counter, and herbal supplements. Fosfomycin may interact with certain medications, so your healthcare provider can check for potential interactions and adjust your treatment plan accordingly.
  • Completion of treatment: It’s essential to complete the full course of fosfomycin as prescribed, even if you start feeling better before you’ve finished the medication. Stopping treatment prematurely can lead to incomplete eradication of the infection and potential development of antibiotic resistance.
  • Side effects: Be aware of potential side effects of fosfomycin, such as diarrhea, nausea, vomiting, and abdominal pain. If you experience any severe or persistent side effects, contact your healthcare provider.

By following these precautions and guidelines, you can use fosfomycin safely and effectively under the supervision of your healthcare provider.

What special dietary instructions should I follow?

Regarding special dietary instructions for fosfomycin, there are generally no specific dietary restrictions associated with its use. However, it’s essential to stay hydrated and maintain a healthy diet to support your body’s immune system and overall health during treatment.

What should I do if I forget a dose?

If you forget to take a dose of fosfomycin, take it as soon as you remember, unless it’s almost time for your next scheduled dose. In that case, skip the missed dose and continue with your regular dosing schedule. Do not double the dose to catch up. If you have any concerns or questions about missed doses, consult your healthcare provider or pharmacist for guidance.

What side effects can this medication cause?

Fosfomycin, like any medication, can cause side effects in some individuals. Common side effects associated with fosfomycin use include:

  • Gastrointestinal effects: Nausea, vomiting, diarrhea, abdominal pain, and gastrointestinal discomfort are among the most commonly reported side effects of fosfomycin. These symptoms are usually mild and resolve on their own without any specific treatment.
  • Allergic reactions: Some individuals may experience allergic reactions to fosfomycin, which can manifest as rash, itching, hives, swelling of the face, lips, tongue, or throat, difficulty breathing, or severe dizziness. Allergic reactions to antibiotics require immediate medical attention.
  • Headache: Headaches are another common side effect associated with fosfomycin use. In most cases, these headaches are mild to moderate in severity and resolve on their own.
  • Dizziness: Some people may experience dizziness or lightheadedness while taking fosfomycin. It’s essential to avoid driving or operating machinery if you experience these symptoms until you know how the medication affects you.
  • Vaginal itching or discharge: Women may experience vaginal itching or abnormal vaginal discharge while taking fosfomycin. If these symptoms are severe or persistent, it’s important to inform your healthcare provider.
  • Injection site reactions: In cases where fosfomycin is administered intravenously, injection site reactions such as pain, redness, or swelling may occur.
  • Liver function abnormalities: Rarely, fosfomycin may cause abnormalities in liver function tests. If you experience symptoms such as yellowing of the skin or eyes (jaundice), dark urine, or persistent fatigue, contact your healthcare provider.

It’s important to note that not everyone will experience these side effects, and some individuals may experience side effects not listed here. If you have concerns about potential side effects of fosfomycin or experience any unusual symptoms while taking the medication, contact your healthcare provider for guidance.

What should I know about storage and disposal of this medication?

Storage and Disposal of Foscavir (foscarnet):


  • Store Foscavir vials (powder for injection) at room temperature (between 20-25°C or 68-77°F).
  • Keep the vials in their original packaging to protect them from light.
  • Do not freeze Foscavir.
  • Once reconstituted, the solution should be used immediately. If not used immediately, it can be stored at room temperature for up to 24 hours or refrigerated at 2-8°C (36-46°F) for up to 48 hours. Discard any unused portion after this time.


  • Dispose of unused or expired Foscavir vials and solutions properly according to local regulations for hazardous waste disposal.
  • Do not flush medications down the toilet or pour them into drains unless instructed to do so. Consult your pharmacist or local waste disposal company for guidance on proper disposal methods.

In case of emergency/overdose

  • If you suspect an overdose or experience severe symptoms such as seizures, difficulty breathing, or loss of consciousness, seek emergency medical attention immediately.
  • Contact a poison control center or emergency room for guidance on managing an overdose of Foscavir.

What other information should I know?

  • Keep all appointments with your healthcare provider for monitoring and follow-up during Foscavir treatment.
  • Inform your healthcare provider about all medications, supplements, and herbal products you’re taking to avoid potential drug interactions.
  • Avoid driving or operating heavy machinery if you experience dizziness or other neurological side effects while taking Foscavir.
  • Do not share Foscavir with others, as it is prescribed specifically for your condition and may not be suitable for others.
  • Store Foscavir out of reach of children and pets.
  • Always follow your healthcare provider’s instructions and ask any questions you may have about your treatment with Foscavir.
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