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Nitrofurantoin

Medication urinary antibiotic antibiotic
Aka: Macrobid, Furadantin
Brands seen in Singapore: AA Pharma Nitrofurantoin
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Prescribed for lower urinary tract infections
When to take
NHS: usually 3 to 7 days to treat a UTI
Take with
NHS: with or after a meal or snack · swallowed whole
Pros & cons
Pros
  • NHS: concentrated in pee, where the infection is
  • NHS: alcohol is allowed while taking it
  • NHS: most people feel better within a few days
Cons
  • FDA: nausea 8%, headache 6% in macrobid trials
  • NHS: pee may turn dark yellow or brown
  • FDA: rare lung, liver and nerve harm, some fatal
Sources
  1. HSA — Listing of Registered Therapeutic Products (open dataset on data.gov.sg; same register as HSA Infosearch) · read 2026-08-27
    what it says
    “Only 2 nitrofurantoin products on the register, both 'Prescription Only': SIN00290P AA PHARMA NITROFURANTOIN TABLET 100 mg and SIN00439P AA PHARMA NITROFURANTOIN TABLET 50 mg, both plain oral tablets, ATC J01XE01.”
  2. MOH National Drug Formulary — AA PHARMA NITROFURANTOIN TABLET 100 MG [SIN00290P], SG product information (last updated 28 July 2026) · read 2026-08-27
    what it says
    “NITROFURANTOIN - 100 MG … Dosage Form: TABLET … Forensic Classification: PRESCRIPTION ONLY MEDICINES … Prescription-only Medicines with Exemptions for Supply without Prescription: NA”
  3. HealthHub (MOH Singapore / Pharmaceutical Society of Singapore) — Nitrofurantoin medication information leaflet (reviewed 24 Apr 2026) · read 2026-08-27
    what it says
    “an antibiotic commonly used in the treatment of urinary tract infections … Take this medication with or after food … Inform your healthcare professional if you have Glucose-6-Phosphate-Dehydrogenase (G6PD) deficiency … may also cause your urine to turn dark yellow or brown.”
  4. NHS Medicines A-Z — About nitrofurantoin (brand name: Macrobid; reviewed 6 Jan 2026) · read 2026-08-27
    what it says
    “your body quickly filters it out of your blood and into your pee … the medicine is concentrated at the site of infection … You'll feel better within a few days for most infections. You can drink alcohol while taking nitrofurantoin.”
  5. NHS Medicines A-Z — How and when to take nitrofurantoin (reviewed 6 Jan 2026) · read 2026-08-27
    what it says
    “100mg, taken as slow release capsules, twice a day · 50mg, taken as standard tablets or capsules, 4 times a day · 100mg … 4 times a day, for severe infections … Take nitrofurantoin with or after a meal or snack.”
  6. NHS Medicines A-Z — Who can and cannot take nitrofurantoin (reviewed 6 Jan 2026) · read 2026-08-27
    what it says
    “tell your doctor if you have: porphyria … glucose-6-phosphate dehydrogenase (G6PD) deficiency … severe kidney disease … diabetes … a lung condition … problems with your liver … anaemia or vitamin B deficiency.”
  7. NHS Medicines A-Z — Side effects of nitrofurantoin (reviewed 6 Jan 2026) · read 2026-08-27
    what it says
    “Serious side effects are rare and happen in less than 1 in 1,000 people … signs of lung problems … a sign of liver or gallbladder problems … pins and needles, tingling sensations, numbness or weakness.”
  8. NHS Medicines A-Z — Taking nitrofurantoin with other medicines and herbal supplements (reviewed 6 Jan 2026) · read 2026-08-27
    what it says
    “indigestion remedies known as antacids, particularly those that contain magnesium … antibiotics known as quinolones … Typhoid vaccines given by mouth may not work properly if you're taking nitrofurantoin. It does not affect typhoid vaccines given by injection.”
  9. FDA / openFDA drug label — Macrobid (nitrofurantoin monohydrate/macrocrystals) capsules, prescribing information (effective 9 Feb 2026) · read 2026-08-27
    what it says
    “Adults and Pediatric Patients Over 12 Years: One 100 mg capsule every 12 hours for seven days … Anuria, oliguria, or significant impairment of renal function (creatinine clearance under 60 mL per minute …) are contraindications … nausea (8%), headache (6%).”
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Updated 2026-08-29. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.