Fosomycin is a medicine that treats the bacteria that cause urinary tract infections (UTIs) and bladder infections such as cystitis. It can also be used to treat prostatis (an infection of the prostate gland in men). More information

A doctor will review your order and write you a prescription, if appropriate. This prescription is then forwarded to a pharmacy. The pharmacy will have your medicine delivered to you within one to three working days. Read more about this process here.

Instruction costs (includes consult & service fee)
Service – Instruction costs (includes consult & service fee)
Patient Leaflet(s)

Fosfomyin is an antibiotic medicine for the treatment of bladder and urinary tract infections, which are very common. It is also sometimes used to treat prostate infections in men. This medicine is suitable for men, women and children over 12 years of age. It is a granular powder and should be dissolved in cold water before taking. 

What is Fosfomycin? 

Fosomycin is a medicine that treats the bacteria that cause urinary tract infections (UTIs) and bladder infections such as cystitis. It can also be used to treat prostatis (an infection of the prostate gland in men). 

This medicine is sometimes sold under the brand name of Monurol. Fosomycin is an antibiotic. An antibiotic fights bacterial infections and stops the bacteria from reproducing and spreading. This happens if the immune system cannot fight the infection.  

Bacterial infections can get worse rapidly if they are not treated and a urinary tract infection can lead to a kidney infection if ignored. So if you suspect you have a urinary tract infection of any kind you should see a doctor as soon as possible for treatment. The doctor is likely to test your urine to identify if you have an infection, what it is and what the most suitable form of treatment is for your situation. This is important as different types of bacteria need different forms of treatment. 

Fosomycin only treats bacterial infections, it does not work on viral infections. 

When is Fosomycin used? 

Fosfomycin is used to treat urinary tract infections (UTIs) such as acute cystitis. These infections can occur in men and women. 

UTIs are very common and tend to be recurrent. If you have suffered from this kind of infection before you are likely to know the signs if it occurs again, so you can seek immediate treatment. 

A urinary tract infection can occur in different parts of the urinary tract, including the bladder, urethra and kidneys. However, most urinary tract infections are in the lower urinary tract area.  

Note – Fosfomycin should only be used for the treatment of bladder and urethra infections; it should not be used as a treatment for a kidney infection. A  kidney infection needs different, specialised treatment and is a more serious condition. 

One of the most common urinary tract infections is cystitis, which is a bladder infection. It mainly occurs in women but can be experienced by men too. The most common symptoms of urinary tract infections and cystitis are: 

  • Pain and/or a burning or stinging sensation on urinating; 
  • The frequent urge to urinate with only a few drops appearing; 
  • Blood appearing in the urine; 
  • Cloudy urine; 
  • Strong smelling urine; 
  • Pain in the pelvic region for women; 
  • Dark coloured urine. 

Cystitis can clear up on its own if you have a mild case. This can be helped by drinking lots of fluids. However, if your symptoms continue for more than 2-3 days you should not ignore them but see a doctor as medication will clear the infection quickly. If cystitis is left untreated it can lead to a more serious infection, such as a kidney infection, or even sepsis, which is an inflammation of the whole body. If you feel unwell with fever or see blood in the urine then you must see your doctor immediately. 

Cystitis is caused by the transfer of bacteria, which provokes an infection. The most common causes of cystitis (and urinary tract infections) are:  

  • Wiping from back to front when going to the toilet; 
  • Inserting foreign objects into the vagina; 
  • Using tampons; 
  • Having a catheter inserted into the urethra to drain the bladder as the changing of the catheter can cause small lesions which can increase the possibility of infection; 
  • Having kidney stones, which can restrict the flow of urine and cause bacteria to multiply in the bladder; 
  • Having an enlarged prostate gland, which means the bladder does not fully empty on urination; 
  • Using a diaphragm for contraception; 
  • Having sex (an infection can appear up to 2 days after intercourse has taken place); 
  • Having sex more frequently than usual (known as honeymoon cystitis); 
  • Being pregnant due to hormone changes; 
  • Going through the menopause due to changes in the vagina; 
  • Using creams or other scented products in the vagina, including vaginal deodorants, shower and bath products – it is much better to let the vagina cleanse itself naturally; 
  • Having a weak immune system. 

Women are more likely to suffer from cystitis than men as their anatomy means their urethra is nearer to their anus therefore it is easier for bacteria to enter the bladder and cause an infection. 

Bladder infections are due to bacteria entering the urinary tract. Many of these infections are caused by the E. coli bacteria which can be found in faeces and the gut. 

Another cause of UTIs is the bacteria staphylococcus saprophyticus, which lives naturally in the vagina. This bacteria can be transferred to the urethra during sexual intercourse which can cause an infection. The process of intercourse can also cause the bacteria to travel further up the urethra. 

Often the body’s immune system fights the microbes that cause these infections on its own. But sometimes it is not able to do so and needs medication. 

Fosfomycin can help the immune system fight urinary infections. Some of the bacteria that cause a urinary tract infection have a protective wall around them. Fosfomycin can break through this wall, kill the bacteria and prevent the bacteria cells spreading. When this happens the immune system naturally takes back control of the body and fights the infection.  

Fosfomycin is also used to treat prostatitis, which is an inflammation and swelling of the prostate gland in men. This is the gland that produces semen. Prostatitis occurs when there is a bacterial infection of this gland, that can be caused by urine entering the prostate. 

How do you use Fosfomycin? 

Fosfomycin comes as a granular powder.  

The pack should be emptied into a glass of cold water and stirred if it does not all dissolve. You then drink the solution immediately. You should only use cold water, not hot or warm water. 

It is advisable to take this medicine after urinating, before you go to bed and on an empty stomach. 

You should expect to see an improvement in your symptoms in 2-3 days. If this does not happen then you should see your doctor as the infection may get worse. 

You only take one dose to treat a urinary infection – do not take more than this i.e. you do not take this medicine every day. 

Fosfomycin can be taken by women, men and children over 12 years of age. 

What dosages are there? 

The usual dose of Fosfomycin is one 3 gram pack dissolved in water.  

You should not take more than one pack during a single course of treatment as this could be harmful. 

This medicine should not be taken by children under 12 years of age. 

If you experience recurrent urinary tract infections you should see your doctor as there may be another problem, such as a kidney infection.  

What are the side effects of Fosfomycin? 

As with all medicines, there is the possibility of side effects when you take Fosfomycin. These can include: 

  • Diarrhoea (a common effect of taking antibiotics); 
  • Stomach upsets; 
  • Fever; 
  • Dizziness; 
  • Headache; 
  • Feeling sick; 
  • Infection of the genitals; 
  • Feeling weak. 

It is important that you tell your doctor or pharmacist if you have taken a medicine known as metoclopramide (which prevents you from feeling sick) with Fosfomycin, as the two can interact. 

You should also inform your doctor of any other medicines you are taking, including herbal medicines. 

When shouldn’t you use Fosfomycin? 

You should not use Fosfomycin if you: 

  • Are allergic to any of the ingredients on the package leaflet; 
  • Have severe kidney problems; 
  • Are undergoing haemodialysis (a blood cleaning procedure); 
  • Are under 12 years of age.  
  • If you have taken the anti-sickness medication metoclopramide you should inform your doctor before taking Fosfomycin. 
  • If you are pregnant, planning to become pregnant or breastfeeding you should only take this medication if a doctor has advised you. 
  • Fosfomycin can pass into breast milk and generally not advised  while breastfeeding. 

Does Fosfomycin interact with other medications? 

It is important to tell your doctor if you are taking any other medications as Fosfomycin may interact with them. This includes herbal medicines. It also includes the anti-sickness medicine metoclopramide. 

Where can you buy Fosfomycin? 

Fosfomycin can only be prescribed by a doctor. You cannot buy it over-the-counter in a pharmacy. 

Can I get Fosfomycin without a prescription?  

No, you cannot get Fosfomycin without a prescription. 


Cornforth, T. An Overview of Urinary Tract Infections. August 9, 2019. Retrieved 10 December, 2019 from 

Fosfomycin Tromethamine Packet. Retrieved 10 December, 2019 from 

Overview. Cystitis. 9 August, 2018. Retrieved 10 December, 2019 from 

Henderson, R. 15 October, 2019. Cystitis: how to treat urinary tract infections. Retreived 10 December, 2019 from 

Package leaflet: Information for the user Fosfomycin 3 g, granules for oral solution Fosfomycine Trometamol. November, 2017. Retrieved 10 December, 2019 from 

Prostatitis. Mayo Clinic. (N.D.). Retrieved 10 December, 2019 from 

Zhanel, G.G., Walkty, A.J., Karlowsky, J.A.   Fosfomycin: A First-Line Oral Therapy for Acute Uncomplicated Cystitis. November, 13, 2015. Retrieved 10 December, 2019 from 

Assessed by:

Dr Imran Malik, General practitioner
Registration number: GMC: 4741365

Dr Imran Malik studied undergraduate medicine at King's College University in Central London and clinical studies at the prestigious King's College Hospital. He graduated with a MBBS degree in 2000 and went on to gain postgraduate memberships with the Royal Society of Medicine and also General Practice in 2006.