Nitrofurantoin — NZ Medication Guide
📋 Reviewed by a Registered Pharmacist NZ — This information is for general educational purposes only and does not replace professional medical advice. Always consult your doctor or pharmacist before starting, stopping, or changing any medication.
What is Nitrofurantoin?
Nitrofurantoin is an antibiotic used specifically for the treatment and prevention of urinary tract infections (UTIs). This medication is funded by Pharmac for UTI treatment and prophylaxis.
What is Nitrofurantoin Used For?
Nitrofurantoin is used for uncomplicated lower urinary tract infections (cystitis) caused by susceptible organisms, and for prophylaxis of recurrent UTIs in women.
How Does Nitrofurantoin Work?
Nitrofurantoin is reduced by bacterial enzymes to reactive intermediates that damage bacterial DNA, inhibit ribosomal protein synthesis, impair cell wall formation, and affect several metabolic pathways simultaneously. This multi-mechanism action makes it very difficult for bacteria to develop resistance.
How to Take Nitrofurantoin
Treatment of acute UTI: nitrofurantoin modified-release (MR) capsules 100 mg twice daily for 5 days (Macrobid®), or immediate-release 50–100 mg four times daily for 5–7 days. For prophylaxis: 50–100 mg once nightly. Take with food to improve absorption and reduce nausea. Urine may turn brown — this is harmless.
Common Side Effects of Nitrofurantoin
- Nausea and vomiting (take with food)
- Headache
- Dizziness
- Brown urine discolouration (harmless)
- Vaginal candidiasis (thrush)
Serious Side Effects — Seek Medical Attention
Contact your doctor or call 111 immediately if you experience any of the following:
- Pulmonary reactions (rare — acute: fever, cough, eosinophilia; chronic: pulmonary fibrosis with long-term use — seek medical attention for new cough or breathlessness)
- Hepatotoxicity (rare but serious — particularly with long-term use)
- Peripheral neuropathy (rare — with prolonged use or renal impairment)
- Haemolytic anaemia (in G6PD deficiency)
Drug Interactions
Nitrofurantoin may interact with other medicines. Always inform your doctor and pharmacist of all medications you are taking. Key interactions include:
- Antacids containing magnesium trisilicate (reduce nitrofurantoin absorption)
- Probenecid (reduces renal tubular secretion — increases nitrofurantoin toxicity)
New Zealand Prescribing Information
Nitrofurantoin (50 mg tablets — Nitrofurantoin SR; 100 mg modified-release capsules — Macrobid®) is funded by Pharmac. It is contraindicated at eGFR <30 mL/min/1.73m² (reduced efficacy and increased toxicity). In NZ, nitrofurantoin is recommended by BPAC NZ as a first-line oral antibiotic for uncomplicated cystitis due to high local susceptibility rates and low resistance.
Frequently Asked Questions
Can I use nitrofurantoin for kidney infections?
No — nitrofurantoin is only effective for lower urinary tract infections (bladder/cystitis). It does not achieve adequate tissue concentrations in the kidneys or bloodstream. Kidney infections (pyelonephritis) require systemic antibiotics such as trimethoprim, cefalexin, or ciprofloxacin.
Why is my urine brown while taking nitrofurantoin?
Nitrofurantoin and its metabolites are excreted in the urine, giving it a yellow to brown colour. This is harmless and expected — it is not a sign of a problem. The discolouration disappears when you stop taking the medicine.
⚠️ Disclaimer: This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your doctor or a qualified health provider. In New Zealand, medication availability and funding may vary — check with Pharmac or your pharmacist for current information.
Reviewed by a Registered Pharmacist NZ
References & Further Information
The following New Zealand and international resources were used to inform this page: