India · Uncomplicated UTI Treatment · Recurrent UTI Prophylaxis · Pregnancy UTI · Macrobid · Nitrofurantoin · Uriforce
✗ CrCl < 30 mL/min — ineffective and toxic
✗ 3rd trimester pregnancy (haemolytic anaemia risk in neonate)
✗ G6PD deficiency (haemolytic anaemia)
⚠️ Pulmonary reactions (rare, chronic use) — monitor
⚠️ Peripheral neuropathy with prolonged use
✓ Safe in 1st–2nd trimester for short-course treatment
Nitrofurantoin is an oral urinary tract antiseptic concentrated exclusively in the urine — serum levels are negligible, making it effective only for lower UTI (cystitis) and not pyelonephritis or systemic infections. Its major clinical advantage in India is its very low resistance rate among E. coli (<10% in most Indian centres, compared to 50–80% resistance to ciprofloxacin). This makes nitrofurantoin an excellent empirical choice for uncomplicated lower UTI in women, where ciprofloxacin resistance has rendered that drug unreliable without culture confirmation. It is also the preferred agent for recurrent UTI prophylaxis and for treating UTI in pregnancy (1st and 2nd trimesters).
The shift away from ciprofloxacin as empirical UTI therapy is one of the most important antimicrobial stewardship messages in Indian medicine. E. coli — which causes 80–85% of uncomplicated UTIs — has resistance rates to ciprofloxacin exceeding 50% in many urban Indian centres. Nitrofurantoin resistance in E. coli remains below 10% in most studies because nitrofurantoin's mechanism (requiring multiple bacterial enzymes for activation) makes resistance development difficult and because its urinary-only concentration prevents selection pressure on non-urinary bacteria. For uncomplicated cystitis in women, nitrofurantoin 100mg MR twice daily for 5 days is now the BNF and NICE first-line recommendation.
Nitrofurantoin requires adequate renal function to concentrate in the urine — below CrCl 30 mL/min, urinary concentrations are insufficient for antibacterial efficacy (treatment failure) AND systemic drug accumulation causes peripheral neuropathy and pulmonary toxicity. It is therefore contraindicated when CrCl <30. For UTI in CKD patients: use co-amoxiclav (if susceptible), fosfomycin (if available), or trimethoprim (if CrCl >15 and susceptibility confirmed). Always check eGFR before prescribing nitrofurantoin — particularly in elderly women where CrCl is frequently below 30 despite apparently normal creatinine.
Nitrofurantoin is safe for treating UTI and asymptomatic bacteriuria in the 1st and 2nd trimesters of pregnancy. It is contraindicated at term (after 36 weeks) and in the 3rd trimester because at delivery, neonatal red blood cell enzymes are immature and nitrofurantoin can cause haemolytic anaemia in the neonate. For UTI in the 3rd trimester: cephalexin or co-amoxiclav are preferred. Untreated UTI and asymptomatic bacteriuria in pregnancy significantly increases the risk of pyelonephritis and preterm labour — always treat with culture-guided therapy.