Nitrofurantoin
⚠️ Nitrofurantoin can rarely cause a lupus-like syndrome.
❌ Do not use if eGFR < 45 ml/minute (ineffective + ↑ risk of toxicity).
📖 About
Always check the BNF link here.
- 💊 First-line option for uncomplicated urinary tract infection (UTI) if renal function is normal.
- 🩺 Only effective in the urinary tract (concentrates in urine, not systemic tissues).
⚙️ Action
- ⚖️ Low dose → bacteriostatic; high dose → bactericidal.
- 🧪 Antibacterial effect confined to urine.
- 🌡️ More effective in acidic urine (pH ~5.5).
🌍 Indications
- 🦠 Active against many Gram-positive and Gram-negative urinary pathogens.
- 💊 Treatment and prophylaxis of recurrent UTI.
📊 Dose
- 💊 50–100 mg QDS, or 100 mg MR BD (modified-release also suitable).
- 📆 Usual course: 3 days (women), up to 7 days if complicated infection, in men, or in pregnancy.
📋 Dose Range (check BNF / datasheet)
| Preparation | Dose | Frequency | Notes |
|---|
| Nitrofurantoin | 50 mg | QDS | 3 days (women) / 7 days (men, pregnancy). Only if eGFR > 45 ml/min. |
| Nitrofurantoin MR | 100 mg | BD | 3 days (women) / 7 days (men, pregnancy). Only if eGFR > 45 ml/min. |
🔄 Interactions
- ⚠️ May precipitate haemolysis in patients with G6PD deficiency.
⚠️ Cautions
- ❌ Do not use if eGFR < 45 ml/minute (low urinary levels + ↑ toxicity).
- 🤰 Avoid in late pregnancy (risk of neonatal haemolysis).
- 🫁 Use cautiously in chronic lung disease (can cause pulmonary fibrosis).
- 💊 Long-term use requires monitoring for pulmonary, hepatic, and neurological toxicity.
⛔ Contraindications
- eGFR < 45 ml/minute.
- History of hypersensitivity to nitrofurantoin.
💥 Side Effects
- 🤢 GI: anorexia, nausea, vomiting.
- 🧪 Hepatic: hepatitis, cholestatic jaundice, rare pancreatitis.
- 🫁 Respiratory: pulmonary infiltrates, interstitial fibrosis (chronic use).
- 🩸 Haematological: haemolytic anaemia (esp. G6PD deficiency).
- 🧠 Neurological: peripheral neuropathy (with prolonged therapy).
- 💧 Brown urine (benign but alarming to patients).
- 🧪 Can cause false-positive urine glucose tests.
📚 References
