Nitrofurantoin
Nitrofurantoin is an antibiotic that the NHS describes as a medicine for lower urinary tract infections such as cystitis, and it is available only on prescription. The NHS lists severe kidney problems, lung conditions and liver problems among the reasons it may not be suitable, and notes that it can turn urine dark yellow or brown, which is harmless.
- Generic name
- Nitrofurantoin
- Active ingredient
- Nitrofurantoin
- Product type
- Small-molecule medicine
- Drug class
- Urinary antibacterials
- Brand names
- UK · US
- Routes
- Oral
- Dosage forms
- Tablet, Capsule
- Usual preparations
- The NHS says nitrofurantoin tablets or capsules are swallowed whole (summary of the cited reference, not a prescription)
- Monitoring
- NHS clinical guidance for long-term use says kidney function, liver function and lung symptoms are checked at the start and at regular reviews.
Availability by country
| Country | Status | Note | Source |
|---|---|---|---|
| UK | Prescription only | UK |
Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.
What it is used for
- Lower urinary tract infections such as cystitis
- Helping to prevent urinary tract infections from coming back, when prescribed for that purpose
How it works in the body
Nitrofurantoin belongs to a class of medicines called antibiotics, which work by killing the bacteria that cause infection. Like other antibiotics, it has no effect on colds, flu or other infections caused by viruses. The NHS explains that most of a dose is filtered from the blood into the urine, which concentrates the medicine where the bacteria are. West Yorkshire NHS prescribing guidance says it is unsuitable for upper urinary tract infections such as kidney infections.
Common side effects
- Nausea, diarrhoea, loss of appetite and headaches are the usual side effects the NHS lists; taking the medicine with or after food can ease nausea
- Dark yellow or brown urine is a common effect that the NHS describes as harmless, and the urine returns to its usual colour once the medicine is stopped
Serious: seek help
- Lung problems are among the uncommon serious side effects; a persistent cough or breathing difficulties need urgent medical advice, and the NHS says to call NHS 111 for a serious side effect other than anaphylaxis
- Liver problems such as jaundice (yellowing of the skin or eyes) are uncommon serious effects; the NHS advises calling NHS 111
- A serious allergic reaction (anaphylaxis) is an emergency that needs a 999 call for an ambulance
Cautions and interactions
- The NHS says nitrofurantoin may not be suitable for people who have had an allergic reaction or serious side effect from it, or who have a lung condition, severe kidney problems, diabetes, anaemia, vitamin B deficiency or porphyria, so these are checked first
- G6PD deficiency, liver problems and conditions causing severe weakness are also listed by the NHS as conditions to check
- Kidney function is a key check: NHS clinical guidance describes kidney function as a key check and links poor kidney function with the medicine being less likely to reach useful levels in the urine, and the prescriber decides
- Pregnancy: the NHS says it can usually be taken earlier in pregnancy, but a doctor may not recommend it later on because it can affect the baby's red blood cells
- Breastfeeding: small amounts pass into breast milk and side effects in the baby are unlikely, but the NHS advises checking with a doctor or pharmacist; NHS specialist advice is to avoid it if the infant has G6PD deficiency or jaundice
- Interactions: antacids may interact (MedlinePlus), magnesium trisilicate may reduce absorption, and products that make urine less acidic, such as some cystitis remedies containing potassium citrate or sodium bicarbonate, can weaken its antibacterial action
- It is not recommended for men with suspected prostate involvement in NICE guidance on lower urinary tract infections
- It can cause false results on urine tests for glucose
- The NHS says alcohol can be drunk while taking nitrofurantoin
Interactions
Check interactions
Taking Nitrofurantoin with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".
Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.
No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.
Same-class and related medicines
Same class: Urinary antibacterials
Medicines that share the class of Nitrofurantoin. They are separate medicines with their own licences, doses and interactions, not alternative names for Nitrofurantoin.
Related medicines
Medicines often discussed alongside Nitrofurantoin: used together, compared with it, or acting on the same problem by a different route.
Key facts
| Fact | Detail |
|---|---|
| Medicine type | Antibiotic |
| Used for | Lower urinary tract infections such as cystitis, and helping to prevent them |
| Availability in the UK | Prescription only |
| Harmless effect | Dark yellow or brown urine |
| Rare serious effects | Lung problems, liver problems and allergic reactions |
| Extra care | Severe kidney problems, lung conditions and liver problems |
What is nitrofurantoin used for?
Nitrofurantoin is an antibiotic that the NHS describes as a medicine for lower urinary tract infections, such as cystitis. It is available only with a prescription. The NHS explains that most of a dose is filtered from the blood into the urine, which concentrates the medicine where the bacteria are. It can also be prescribed to help prevent urinary tract infections from coming back. MedlinePlus places it in a class of medicines called antibiotics, which work by killing the bacteria that cause infection. Like other antibiotics, it does not work for colds, flu or other viral infections. NICE guidance on lower urinary tract infections says nitrofurantoin is not recommended for men with suspected prostate involvement. West Yorkshire NHS prescribing guidance adds that it is unsuitable for upper urinary tract infections, such as kidney infections.
How is nitrofurantoin taken?
The NHS says nitrofurantoin is best taken with or after a meal or snack, which helps the body absorb it and helps prevent an upset stomach. Tablets and capsules are swallowed whole rather than chewed or broken. The NHS says a missed dose is skipped if it is nearly time for the next one, and a double dose is not taken to make up for it. The NHS says a doctor should be told if a urinary tract infection does not improve or if symptoms get worse at any time. The NHS stresses the importance of continuing until the course is finished, even after feeling better, to stop the infection coming back.
What are the side effects of nitrofurantoin?
The NHS lists nausea, diarrhoea, loss of appetite and headaches as the usual side effects. Dark yellow or brown urine also occurs, and the NHS describes it as harmless. The urine returns to its usual colour once the medicine is stopped. Side effects usually go away when the medicine is stopped, and taking it with or after food can ease nausea. The NHS says serious side effects are uncommon. They include lung problems, liver problems such as jaundice, and allergic reactions. Anaphylaxis, a severe allergic reaction, means calling 999 for an ambulance, while the NHS route for other serious side effects is NHS 111. A local NHS leaflet describes shortness of breath or a lingering cough as lung symptoms needing urgent medical advice, and yellowing of the skin or eyes as a possible sign of liver effects.
Who needs extra care with nitrofurantoin?
The NHS says most adults and children can take nitrofurantoin, but it is not suitable for everyone. Previous allergic reactions or serious side effects from it, a lung condition, severe kidney problems, diabetes, anaemia, vitamin B deficiency and porphyria are all listed as reasons to check first. The NHS also lists G6PD deficiency, liver problems and conditions causing severe weakness. Kidney function is a key check in NHS clinical guidance. The guidance links poor kidney function with the medicine being less likely to reach useful levels in the urine. Sources differ on the exact kidney-function limit, so the prescriber decides.
Pregnancy, breastfeeding and other medicines
The NHS says nitrofurantoin can usually be taken earlier in pregnancy. A doctor may not recommend it later on, because it can affect the baby's red blood cells. Small amounts pass into breast milk and are unlikely to cause side effects in a baby, though the NHS advises checking with a doctor or pharmacist first. NHS specialist advice is to avoid it if the infant has G6PD deficiency or jaundice, because of the risk of haemolytic anaemia. Among other medicines, MedlinePlus lists antacids as a nonprescription product that may interact. NHS pharmacy guidance says magnesium trisilicate may reduce absorption. It adds that products which make urine less acidic, such as some cystitis remedies containing potassium citrate or sodium bicarbonate, can weaken the antibiotic's action. The NHS says alcohol can be drunk while taking nitrofurantoin. MedlinePlus also notes that nitrofurantoin can cause false results on urine tests for glucose.
Frequently asked questions
Why does nitrofurantoin turn urine dark?
Dark yellow or brown urine is a known effect of nitrofurantoin, and the NHS describes it as harmless. The urine goes back to its usual colour once the medicine has been stopped.
Can nitrofurantoin treat a kidney infection?
West Yorkshire NHS prescribing guidance says nitrofurantoin is unsuitable for upper urinary tract infections, which include kidney infections. The NHS describes it as a medicine for lower urinary tract infections such as cystitis.
Does nitrofurantoin work for colds or flu?
No: MedlinePlus says antibiotics such as nitrofurantoin will not work for colds, flu or other viral infections. It is an antibiotic that works by killing the bacteria that cause infection.
Can nitrofurantoin be used in pregnancy?
The NHS says nitrofurantoin can usually be taken earlier in pregnancy, but a doctor may not recommend it later on because it can affect the baby's red blood cells. The NHS says the doctor weighs up the benefits and risks with the person.
What does the NHS say about kidney problems and nitrofurantoin?
The NHS lists severe kidney problems among the conditions to check before taking nitrofurantoin. NHS clinical guidance describes kidney function as a key check and links poor kidney function with the medicine being less likely to reach useful levels in the urine.
Connected pages in detail
What each linked page on Anatomy Nexus covers, in a line, for Nitrofurantoin.
Conditions
- Urinary tract infection Bacterial infection of the bladder (cystitis) or, when it ascends, the kidney (pyelonephritis), usually by gut bacteria such as Escherichia coli.
Medical tests
- Kidney function tests Creatinine and urea are waste products the kidneys should clear; how much builds up in blood shows how well they are filtering.
Medications
- Amoxicillin A widely used penicillin antibiotic that kills bacteria by breaking their cell walls, prescribed for chest, ear, sinus.
Drug classes
- Urinary antibacterials Antibiotics used for urinary tract infections.