Fosfomycin is an antibiotic treatment for cystitis and urinary tract infections (UTIs). Only one dose is typically needed for adults. We can only prescribe this if MacroBID is unsuitable for you.
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Important: MacroBID is the first line treatment we offer for UTIs and cystitis based on national guidelines. Therefore our doctors will only consider recommending fosfomycin if MacroBID is unsuitable for you. Request MacroBID now.
Fosfomycin is an effective antibiotic treatment for urinary tract infections (UTIs) like cystitis, in women. It comes in the form of a powder solution that you mix with water and drink. Only one dose is typically required for treatment in adults. Each 3g packet of Fosfomycin contains 5631mg of the active ingredient fosfomycin trometamol.
1 sachet only / 3 g - £24.00
Fosfomycin is an effective antibiotic treatment for urinary tract infections (UTIs) in women. This is an infection in any part of the urinary tract. This can include the bladder (cystitis), which is the most common UTI.
Fosfomycin is specifically prescribed for ‘uncomplicated cases’ of UTIs in women. This simply means an infection in women who are otherwise healthy and not pregnant. It is a cheaper, generic version of the branded medication Monuril. Both work in exactly the same way.
Please note, MacroBID is the first line treatment we offer for UTIs and cystitis based on national guidelines. Therefore our doctors will only consider recommending fosfomycin if MacroBID is unsuitable for you. Request MacroBID now so they can check this.
If you have any questions about cystitis treatment, you can send our doctors a private message through your account.
Fosfomycin is a broad spectrum antibiotic. This means it works against a variety of bacteria that cause infections like UTIs. It kills and prevents this bacteria from growing again and the infection returning.
Your symptoms should begin to clear after 2 to 3 days of taking fosfomycin. While the medication works quickly, it works best if you take it:
- after peeing when your bladder is empty, like before bed
- on an empty stomach, or at least 2 hours after eating
Fosfomycin may be less effective or even unsafe for those with certain medical conditions or if you take particular medications.
Speak to your doctor beforehand if you:
- have ever had diarrhoea after taking antibiotics
- have an intolerance for any sugars
- are currently pregnant or planning to get pregnant
- are breastfeeding
Since dizziness and tiredness are side effects of fosfomycin, you should also avoid certain activities after taking this, like driving.
Fosfomycin is typically a single dose treatment, which means you only need to take one 3g sachet. You should only take additional doses if your doctor tells you to do so. Always follow your doctor’s instructions to take fosfomycin correctly.
- Pour the whole sachet of powder into a glass of water that’s either cold or room temperature
- Stir this so the powder dissolves
- Swallow this straight away
Do not consume the powder on its own without water.
You can take fosfomycin with or without food, though it is more effective on an empty stomach.
How quickly does fosfomycin work?
Fosfomycin usually works quickly. Your symptoms should begin to improve within 2 to 3 days.
How often can you take fosfomycin?
Normally only one dose of fosfomycin is prescribed to treat UTIs like cystitis, so you don’t need to worry about repeat doses.
If your doctor does recommend additional doses, follow their instructions about how long to wait between doses.
Adults and children aged between 13 and 17 years old can take fosfomycin although you need a prescription for this. Adults are usually prescribed a single 3g sachet to be consumed in one go. A doctor will decide what dose a child should take.
Our doctors can only prescribe fosfomycin if MacroBID is unsuitable for you. Please request MacroBID so they can check:
- whether MacroBID is right for you
- if fosfomycin could be a suitable alternative treatment
Like all medications, fosfomycin can cause side effects. However these should go away on their own.
Common side effects include:
- pain in your abdomen
Speak to your doctor straight away if you:
- show signs of an allergic reaction like breathing difficulties, a sudden rash, or swelling in your face, tongue or throat
- get pain or cramps in your stomach
- get persistent diarrhoea
- feel pain when you pee
- notice blood in your poo or pee
You should not take Fosfomycin if you are:
- under 12 years old
- allergic to any of the ingredients in fosfomycin
- have kidney problems
You should also tell your doctor about any medications you’re taking, in particular:
- metoclopramide, an anti sickness medication that can affect fosfomycin
- any hormonal contraception as some antibiotics can make these less effective
Our doctors will ask about your medical history when you request cystitis treatment through Asda Online Doctor.
For more information, view and download the patient information leaflet for fosfomycin.
Fosfomycin is considered a safe, effective treatment for UTIs and cystitis by doctors. Since it is quickly absorbed into the body, symptoms should improve within 3 days of taking this.
Yes, you need a prescription to get fosfomycin. You cannot get fosfomycin over the counter.
A doctor needs to check that this is safe for you based on your medical history. This includes checking that fosfomycin won’t interact with or make any other medications you take less effective, and vice versa.
Our doctors can only prescribe fosfomycin if MacroBID is unsuitable for you. They will send you a message with advice about treatment once you request MacroBID and they have reviewed this order.
We can deliver your medication to you if we prescribe cystitis treatment. Alternatively you can collect this from your nearest Asda Pharmacy via Click & Collect.
MacroBID is a branded medication which contains a different active ingredient, nitrofurantoin. Medications that contain nitrofurantoin are the first line treatment for UTIs because there is a lower chance of bacteria developing a resistance to these (bacterial resistance). Fosfomycin is reserved for patients who cannot take nitrofurantoin.
A 2018 study compared the effectiveness of nitrofurantoin and fosfomycin as UTI treatments. After almost 30 days, 70% of patients were cured after taking nitrofurantoin compared to 58% of those on fosfomycin.
If MacroBID is not suitable for you, our doctors may recommend fosfomycin instead.
If you visit your GP, they may also prescribe trimethoprim to treat your UTI, or amoxicillin or cefalexin if your initial medication doesn't work.
Dr Kathryn Basford
Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with ZAVA. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.Meet our doctors
Article created: 14 Sep 2022
Last reviewed: 14 Sep 2022
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https://jamanetwork.com/journals/jama/fullarticle/2679131 [May 2018] [accessed September 2022]
Cystitis bladder infections are caused by bacteria and need to be treated with antibiotics. Asda Online Doctor by ZAVA offers a variety of treatment through a convenient, discreet service.