Frequently asked questions with Nitrofurantoin 50mg tablets
What is Nitrofurantoin?
Nitrofurantoin is a UK-licensed narrow-spectrum nitrofuran antibiotic used for lower urinary tract infection and recurrent UTI prophylaxis. In UK use since 1953, still the NICE first-line for uncomplicated lower UTI in non-pregnant women and the first-line prophylactic antibiotic for recurrent UTI.
What is Nitrofurantoin used for?
Treatment of acute lower urinary tract infection (50mg four times a day for 3 days in women) and long-term prophylaxis of recurrent UTI (50mg once at night). Also used in asymptomatic bacteriuria in pregnancy second trimester (under GP guidance) and peri-operative prophylaxis for urology procedures.
What are Nitrofurantoin tablets used for?
The 50mg immediate-release tablet is used for both acute UTI (four times a day for 3 days) and long-term prophylaxis of recurrent UTI (once at night). The MR 100mg capsule is a different form used only for acute UTI, taken twice a day.
What does Nitrofurantoin treat?
Lower urinary tract infection caused by E. coli, Staphylococcus saprophyticus, Enterococcus, Klebsiella and some Enterobacter species. It does not treat pyelonephritis or systemic infection, as serum concentrations are too low.
Can Nitrofurantoin treat UTI?
Yes. For uncomplicated lower UTI in non-pregnant women aged 16 to 64, nitrofurantoin is UK first-line. The 50mg tablet is given four times a day for 3 days, the MR 100mg capsule twice a day for 3 days, both work equally well.
Does Nitrofurantoin treat UTI?
Yes, specifically lower UTI (bladder infection, cystitis). It does not treat upper UTI (kidney infection, pyelonephritis), which needs a systemic antibiotic like co-amoxiclav.
Is Nitrofurantoin an antibiotic?
Yes. Nitrofurantoin is a synthetic nitrofuran antibiotic that selectively targets bacteria in the urinary tract.
Is Nitrofurantoin a strong antibiotic?
It is highly effective against the bacteria that cause the common lower UTI, where it achieves very high urinary concentrations. It is not a broad-spectrum antibiotic for systemic infections. Within its intended use, it is one of the most effective antibiotics in the UK formulary with low resistance.
Does Nitrofurantoin contain penicillin?
No. Nitrofurantoin is in a different chemical class (nitrofurans) and is safe to use in people with penicillin allergy.
Is Nitrofurantoin a penicillin?
No. Nitrofurantoin is a nitrofuran antibiotic, unrelated to penicillins. It is suitable for people with penicillin allergy.
How to take Nitrofurantoin?
For acute UTI, one 50mg tablet four times a day, spaced evenly (every 6 hours), for 3 days (women) or 7 days (men or complicated UTI). For prophylaxis, one 50mg tablet once at night. Take with food or milk. Swallow whole with plenty of water. Complete the full course.
How to take Nitrofurantoin for UTI?
For acute lower UTI in non-pregnant women aged 16 to 64, one 50mg tablet every 6 hours for 3 days (12 tablets total). Take with food or milk. Space doses as evenly as possible to maintain urinary concentration.
Nitrofurantoin dosage for UTI, how many days?
3 days for uncomplicated lower UTI in non-pregnant women aged 16 to 64 (NICE NG109). 7 days in men or complicated lower UTI. 7 days in pregnancy second trimester (specialist decision).
Nitrofurantoin 100mg dosage for UTI, how many days?
The 100mg MR capsule is dosed as 100mg modified-release twice a day for 3 days. The 50mg immediate-release tablet is dosed as 50mg four times a day for 3 days. Both achieve the same total daily dose and clinical outcome.
Nitrofurantoin dose for UTI, female?
For acute UTI, 50mg four times a day for 3 days (12 tablets total). For recurrent UTI prophylaxis, 50mg once at night long-term. Same for adolescents 16+, same for women up to 64. Above 64, eGFR check first.
How many hours apart should I take Nitrofurantoin?
For acute UTI at 50mg four times a day, space doses roughly every 6 hours (e.g. 8am, 2pm, 8pm, 2am), or every 6 hours when awake with the last dose before bed. For prophylaxis (50mg at night), take at the same time each evening.
How long does Nitrofurantoin take to work?
Symptom improvement within 24 to 48 hours of starting an acute UTI course. Full UTI resolution over the 3-day course. For prophylaxis, the aim is to prevent future UTIs rather than treat current symptoms.
How long does Nitrofurantoin take to work on a UTI?
Most women feel better within 24 to 48 hours. Dysuria and urgency usually settle first, followed by frequency over the next 1 to 2 days. Full resolution by day 3 to 5.
How quickly does Nitrofurantoin work?
The first dose starts reducing bacterial load in the bladder within hours. Noticeable symptom improvement by 24 to 48 hours in most women.
How long does it take for Nitrofurantoin to work?
24 to 48 hours for symptom improvement, 3 days for the full acute UTI course. If no improvement by 48 hours, speak to your prescriber, you may need urine culture or a different antibiotic.
How long for Nitrofurantoin to work?
Most women feel better in 1 to 2 days. If symptoms are worsening or you develop fever, loin pain or vomiting, seek urgent review.
Nitrofurantoin, how long to work?
Symptom improvement at 24 to 48 hours. Full acute UTI course 3 days. Complete the course even if you feel better after day 1 or 2.
Nitrofurantoin, how long does it take to work?
Clinical improvement at 24 to 48 hours, full UTI clearance by end of the 3-day course.
Does Nitrofurantoin work?
Yes, within its indication. UK resistance rates for E. coli to nitrofurantoin remain low (around 2 to 5%), which keeps it as first-line. Where it does not work (urine culture shows resistance, or symptoms worsen), a different antibiotic is needed.
Can I drink alcohol with Nitrofurantoin?
No direct pharmacological interaction. However, alcohol irritates the bladder and can prolong UTI symptoms. We recommend avoiding alcohol until the acute course is finished and symptoms have fully resolved. On long-term prophylaxis, keep to UK low-risk guidelines.
Can you drink alcohol with Nitrofurantoin?
There is no pharmacological interaction, so a small amount of alcohol will not stop the antibiotic working. We still advise avoiding alcohol until any acute UTI is fully resolved.
Nitrofurantoin, can you drink alcohol?
No direct interaction, but alcohol can worsen UTI symptoms by irritating the bladder. Avoid during an active acute course and for 48 hours after.
Can you drink on Nitrofurantoin?
Yes without a direct interaction, but we recommend not drinking during an active acute UTI course because alcohol prolongs bladder symptoms and dehydration.
How long after Nitrofurantoin can you drink alcohol?
Since there is no direct pharmacological interaction, you can technically drink from the day after your last tablet. For comfort, we suggest waiting until symptoms have fully resolved, usually 48 to 72 hours after an acute course ends.
Can I take paracetamol with Nitrofurantoin?
Yes. No interaction, paracetamol is useful for UTI pain or any mild fever during the course. Standard adult dose up to 1g four times daily, max 4g in 24 hours.
What can you not take with Nitrofurantoin?
Avoid or separate from magnesium trisilicate antacids (separate by 2 hours), quinolone antibiotics (antagonism, avoid combining), probenecid or sulfinpyrazone (raise toxicity, reduce urine levels), and oral typhoid vaccine (separate by 3 days).
How long do Nitrofurantoin side effects last?
GI side effects (nausea, loss of appetite, headache) usually settle within 24 hours of the course finishing. Urine discoloration clears over 1 to 2 days. Rare pulmonary or hepatic reactions can persist and need medical review.
Can Nitrofurantoin cause thrush?
Yes. Nitrofurantoin can disturb vaginal flora and allow Candida overgrowth. Thrush symptoms (itching, white discharge) can be treated with OTC clotrimazole or oral fluconazole. Thrush risk is low on prophylactic doses (50mg at night) but may still occur over months.
Does Nitrofurantoin make you urinate more?
No, the drug itself does not change urine volume. However, UTI itself causes urinary frequency, and that symptom often improves within 24 to 48 hours of starting the antibiotic.
Does Nitrofurantoin make you sleepy?
Drowsiness is not a common side effect. Headache and dizziness are reported, which can feel like tiredness. If you feel significantly drowsy, speak to your prescriber.
Is Nitrofurantoin safe in pregnancy?
Nitrofurantoin can be used in the first and second trimesters when needed, under GP guidance. It is contraindicated in the last (third) trimester because of neonatal haemolytic anaemia risk. For UTI in pregnancy, cefalexin is often preferred at term.
How long does Nitrofurantoin stay in your system?
Plasma half-life is around 1 hour, so the drug is cleared within hours of the last dose. Urinary concentration remains high for 24 to 48 hours after an acute course ends, which is why the full course still clears the UTI effectively.
Who can take Nitrofurantoin?
For acute UTI, non-pregnant women aged 16 to 64 with uncomplicated lower UTI, eGFR 45 or above, no G6PD deficiency, no history of nitrofurantoin pulmonary or hepatic reactions. Men, pregnant women and over-65s need case-by-case prescriber review. For prophylaxis, adults with recurrent UTI meeting NICE CKS criteria.
How is the 50mg tablet different from the 100mg MR capsule?
Same drug, different formulation. The 50mg tablet is immediate-release and dosed four times a day for acute UTI (or once at night for prophylaxis). The 100mg MR capsule is modified-release and dosed twice a day for acute UTI only. The 50mg tablet is preferred for long-term prophylaxis because of the lower nightly dose.
Can I buy Nitrofurantoin over the counter?
Not directly. Nitrofurantoin is prescription-only. However, NHS Pharmacy First (2024) lets women aged 16 to 64 with a lower UTI see a community pharmacist who can supply nitrofurantoin under a PGD without a GP appointment. Private online pharmacies supply after a consultation.
Can you buy Nitrofurantoin over the counter?
No. Nitrofurantoin is a POM. The nearest routes are NHS Pharmacy First (women aged 16 to 64 with lower UTI, in-person community pharmacy consultation) or a private online UTI consultation like Courier Pharmacy.
Where can I buy Nitrofurantoin?
At any UK pharmacy with a valid prescription, through NHS Pharmacy First (women aged 16 to 64 with lower UTI, no appointment needed), or online through a registered UK pharmacy like Courier Pharmacy after a consultation.
Can I take Nitrofurantoin long-term for recurrent UTI?
Yes. Long-term prophylaxis at 50mg or 100mg once at night, usually for 6 to 12 months, is standard NICE CKS practice for women with 2 or more UTIs in 6 months or 3 in a year, after other measures (hydration, timed voiding, post-coital voiding, topical vaginal oestrogen in postmenopausal women) have been reviewed. 6-monthly LFTs and clinical pulmonary review are recommended.
Disclaimer
Educational content, not a substitute for medical advice. This page is published by Courier Pharmacy as educational product information about Nitrofurantoin 50mg Tablets. It is not personalised medical advice, and it does not replace a consultation with your prescriber, pharmacist or GP. Always follow the dose and schedule written on your prescription.
UK-licensed Patient Information Leaflet is the authoritative source. Nitrofurantoin 50mg Tablets are a UK-licensed medicine. The Patient Information Leaflet supplied in the pack is the authoritative patient-facing document for the specific product you receive. Always read the PIL before use.
POM status. Prescription-only medicine (POM) under the Human Medicines Regulations 2012. Not a Controlled Drug. Do not share, sell or supply this medicine to anyone else.
Red flags that need urgent review. Loin pain, fever, rigors, nausea or vomiting during a UTI course suggest pyelonephritis (upper UTI). Nitrofurantoin does not reach kidney tissue and will not treat this. Seek urgent review. Visible blood in urine, worsening symptoms despite 48 hours of treatment, or symptoms recurring within 2 weeks of a completed course also need review.
eGFR cut-off warning. Nitrofurantoin is contraindicated in most patients with an estimated glomerular filtration rate below 45 mL/min/1.73m2 (MHRA 2014). In reduced renal function, less drug reaches the urine and more accumulates systemically, lowering effectiveness and raising toxicity.
Pulmonary and hepatic reaction warning. Rare but serious. Acute pulmonary reactions (fever, cough, breathlessness) can occur within days of starting. Chronic pulmonary and hepatic reactions can occur with long-term prophylactic use (over 6 months). Report any new breathlessness, chest pain, cough, or yellow skin or eyes to your prescriber urgently. On long-term prophylaxis, LFTs and clinical pulmonary review every 6 months.
References
- National Institute for Health and Care Excellence (2018, updated 2024). Urinary tract infection (lower): antimicrobial prescribing. NICE guideline NG109. Available at: https://www.nice.org.uk/guidance/ng109
- National Institute for Health and Care Excellence (accessed 2026). Clinical Knowledge Summary: Urinary tract infection (lower), women. Available at: https://cks.nice.org.uk/topics/urinary-tract-infection-lower-women/
- Electronic Medicines Compendium (emc) (2026) [Summary of Product Characteristics for product 3601]. Available at: https://www.medicines.org.uk/emc/product/3601/smpc (Accessed: 13 October 2026).
- Electronic Medicines Compendium (emc) (2026) [Patient information leaflet for product 3601]. Available at: https://www.medicines.org.uk/emc/product/3601/pil (Accessed: 13 October 2026).
- British National Formulary (accessed 2026). Nitrofurantoin. Available at: https://bnf.nice.org.uk/drugs/nitrofurantoin/
- Medicines and Healthcare products Regulatory Agency (2014). Nitrofurantoin now contraindicated in most patients with an estimated glomerular filtration rate of less than 45 mL/min/1.73m2. Drug Safety Update. Available at: https://www.gov.uk/drug-safety-update/nitrofurantoin-now-contraindicated-in-most-patients-with-an-estimated-glomerular-filtration-rate-egfr-of-less-than-45-ml-min-1-73m2
- Medicines and Healthcare products Regulatory Agency (accessed 2026). Nitrofurantoin: reminder of the risks of pulmonary and hepatic adverse drug reactions. Available at: https://www.gov.uk/drug-safety-update/nitrofurantoin-reminder-of-the-risks-of-pulmonary-and-hepatic-adverse-drug-reactions
- UK Health Security Agency (accessed 2026). Managing common infections: guidance for primary care. Available at: https://www.gov.uk/government/publications/managing-common-infections-guidance-for-primary-care
- NHS England (2024). NHS Pharmacy First service, clinical pathway for uncomplicated urinary tract infection in women. Available at: https://www.england.nhs.uk/primary-care/pharmacy/pharmacy-services/pharmacy-first/
- National Health Service (accessed 2026). Urinary tract infections (UTIs). Available at: https://www.nhs.uk/conditions/urinary-tract-infections-utis/
- UK Legislation (2012). The Human Medicines Regulations 2012. Available at: https://www.legislation.gov.uk/uksi/2012/1916/contents/made
- Medicines and Healthcare products Regulatory Agency. Yellow Card scheme. Available at: https://yellowcard.mhra.gov.uk
