Nitrofurantoin
Nitrofurantoin is an antibiotic used to treat common bladder infections such as cystitis.
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Nitrofurantoin (previously sold as MacroBID) is a type of antibiotic that can be taken to treat urinary tract infections (UTIs), like cystitis. Nitrofurantoin is one of the only recommended first-line antibiotics used to treat cystitis in the UK. Nitrofurantoin antibiotics are a generic treatment that contains the active ingredient nitrofurantoin.
A course of treatment for cystitis will usually last 3 days for women, and 7 days for men and pregnant women.



About nitrofurantoin
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Nitrofurantoin is a type of antibiotic that can help treat urinary tract infections (UTIs) like cystitis. It kills harmful bacteria found in your urinary tract that may cause a UTI, including E. coli, Enterococci, Klebsiella and others.
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You should take nitrofurantoin as prescribed by your doctor. When taking nitrofurantoin, make sure that you:
- swallow the capsule whole
- take the capsule with or after food
To treat cystitis, the standard nitrofurantoin dosage is 100mg capsule twice a day, for:
- 3 days for women
- 7 days for men
Nitrofurantoin is usually prescribed for 7 days if you are pregnant, though it is typically advised to avoid prescribing during the third trimester.
While taking 100mg nitrofurantoin twice a day, be sure to space the doses evenly (around 10 to 12 hours apart).
You should finish the whole course of antibiotics, even if you feel better.
How effective is nitrofurantoin at clearing up cystitis?
Nitrofurantoin is very effective in clearing up cystitis and you will feel better within a few days after you take it. Clinical studies have shown nitrofurantoin to help cure between 79% and 92% of people who take nitrofurantoin for a UTI.
After you take nitrofurantoin, your body will pass it through your urinary tract. Many bacteria found in the urinary tract are sensitive to nitrofurantoin. This means nitrofurantoin is an ideal antibiotic to kill the bacteria which cause cystitis and clear it up.
How long does nitrofurantoin take to work on cystitis?
Nitrofurantoin should work on cystitis a few hours after you take your first capsule. You should feel an improvement in the burning sensation when you pee. You may need to pee less often too.
However, to make sure you kill all the bacteria causing the cystitis, it’s important to finish your course of antibiotics. Otherwise, your cystitis can come back or reoccur (this is called recurrent cystitis).
How long does it take nitrofurantoin to clear a UTI?
It usually takes 3 days for nitrofurantoin to clear a UTI in female adult patients, and 7 days in male adult patients and pregnant women.
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Yes, the UTI antibiotic nitrofurantoin is suitable for recurrent cystitis. If you have the symptoms of cystitis more than 3 times in a year, or more than twice in 6 months, you may have recurrent cystitis.
If nitrofurantoin doesn’t cure your cystitis symptoms, speak to your doctor. There could be other underlying causes, such as interstitial cystitis.
“If you think you have recurrent cystitis, speak to your doctor for advice. They can arrange tests to look into the reason why your cystitis keeps coming back, and also test your urine to check which antibiotic is best for you. You may need to start on a low dose of antibiotics, like nitrofurantoin, to take every day to stop your cystitis coming back.” – Dr Brenda Ikeji, Medical Editor.
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Nitrofurantoin can be taken by most adults. If you have certain health conditions or are allergic to nitrofurantoin, you may not be able to take it. You must also tell your doctor if you are pregnant before you take nitrofurantoin. This is because it should not be taken during the third trimester of pregnancy.
For the rest of the time, you will likely be able to take nitrofurantoin during pregnancy or while breastfeeding, and it’s usually seen as a safe treatment. But it’s essential to tell your doctor if you are or think you might be pregnant or if you are breastfeeding before you buy nitrofurantoin.
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You should not take nitrofurantoin if you:
- are allergic to nitrofurantoin or any of the ingredients in nitrofurantoin
- have a kidney disease
- have the blood condition porphyria
- are in the final weeks of pregnancy
- have a genetic condition called G6PD (glucose-6-phosphate dehydrogenase) deficiency
- if you are breastfeeding a child with G6PD deficiency
You should speak to a doctor or pharmacist before taking nitrofurantoin if you have:
- diabetes
- any condition affecting your kidneys
- anaemia or a vitamin B deficiency
- a condition that causes weakness or fatigue
- any lung, liver or nervous system problem
- brown or yellow-coloured urine
Some medicines can interact with how nitrofurantoin works. When you order nitrofurantoin, tell your doctor if you use any other medications, including:
- indigestion remedies for heartburn, such as antacids
- gout treatment, such as probenecid
- glaucoma treatment, such as acetazolamide
- any medicines that cause your urine to become less acidic, such as potassium citrate or sodium citrate (a common cystitis remedy)
- certain antibiotics called quinolones, such as ciprofloxacin
You should also tell your doctor or pharmacist if you have recently had a typhoid vaccine.
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Nitrofurantoin is a prescription-only medication. To get a nitrofurantoin prescription online from ZAVA, you will need to complete a short questionnaire so our doctors can check that nitrofurantoin is suitable before they can prescribe it to you.
When you buy nitrofurantoin online from ZAVA, we post your treatment to your preferred address or your nearest Post Office.
Can you buy nitrofurantoin over the counter?
No, nitrofurantoin is not available over the counter from a pharmacy. You can only get nitrofurantoin on prescription after speaking to a doctor or another prescriber about your cystitis symptoms. If you need to buy nitrofurantoin, fill out our online form and a doctor at ZAVA can check if they can prescribe it for you.
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Before you take nitrofurantoin, you should read the leaflet in the package to learn about all the possible side effects of this antibiotic.
Common side effects of nitrofurantoin include:
- nausea (feeling sick)
- being sick
- diarrhoea
- headaches
- dizziness
- sleepiness
- losing your appetite
When you take nitrofurantoin, you may notice you have dark yellow or brown urine (pee). This is normal and nothing to worry about.
You may feel like you need to vomit after taking your first nitrofurantoin capsule, however this should pass within a few hours. Make sure you take nitrofurantoin with or after food to reduce any nausea and prevent you from feeling sick.
Serious side effects of nitrofurantoin
If you take nitrofurantoin and have symptoms of an allergic reaction, call 999 immediately. Symptoms of an allergic reaction can include breathing difficulties or swelling in your face or throat.
Contact your doctor straight away if you have any of the following symptoms after taking nitrofurantoin:
- fatigue, abdominal pain, joint pain, or swelling
- flu-like symptoms, fever, diarrhoea, or blood in your poo
- blue or purple colour on your skin
- bruising
- yellowing of the skin or the whites of your eyes (jaundice)
- cough or shortness of breath
You should call 999 or go to A&E if you:
- get chest pains
- have difficulty breathing
- get tingling sensations, pins and needles, or numbness
How long do nitrofurantoin side effects last?
The side effects of nitrofurantoin usually pass within just a few hours, and are mild for most people.
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If you have tried nitrofurantoin for cystitis and found it didn’t work for you, speak with your doctor. It’s important to make sure you follow the full course of treatment (usually 3 days for women, normally 7 days for men).
There are alternative antibiotics available to treat cystitis, including trimethoprim if nitrofurantoin does not work for you or if you cannot take it.
Some people find drinking cranberry juice seems to help reduce their chances of recurrent UTIs, among other home remedies, although there isn’t definitive scientific evidence to prove these treatments work.
When going to the toilet, you should:
- wash your genitals with water or perfume-free soap
- wipe yourself from the front to the back to prevent infections
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Do's Don'ts ✓ remember to drink water throughout the day and keep hydrated
✓ pee as often as you need to
✓ take paracetamol if you can, to help with any pain
✓ use a hot water bottle or a heated blanket to relieve any discomfort
✓ wear underwear made from cotton or other natural fibres
✗ avoid tight trousers, leggings or jeans
✗ do not hold in your pee
✗ avoid having sex until your cystitis completely clears
✗ avoid drinks that can trigger your symptoms, such as alcohol and caffeinated drinks
✗ don’t ignore your symptoms if they haven’t improved after 2 days without treatment, or if they get worse

Brenda studied medicine at St Georges University of London and has most recently worked in John Radcliffe Oxford University Hospitals, covering acute and general medicine.
Meet our doctorsLast reviewed: 24 Mar 2025
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Nitrofurantoin, BNF [accessed 4 March 2025]
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Cystitis, NHS [accessed 4 March 2025]
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Nitrofurantoin: properties and potential in treatment of urinary tract infection: a narrative review, PubMed [accessed 4 March 2025]
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Nitrofurantoin, NCBI Bookshelf [accessed 4 March 2025]
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Nitrofurantoin, NICE [accessed 4 March 2025]



Cystitis bladder infections are caused by bacteria and need to be treated with antibiotics. ZAVA offers a variety of treatment through a convenient, discreet service.