Nitrofurantoin (UTI Treatment)

How it works

It is reduced by bacterial flavoproteins to reactive intermediates that damage ribosomal proteins, DNA and other macromolecules, producing broad activity against common urinary pathogens; therapeutic urinary concentrations depend on adequate renal function.

Prescribing in practice

• Avoid in significant renal impairment because inadequate urinary concentrations make it ineffective while increasing systemic toxicity, and avoid at term in pregnancy owing to the risk of neonatal haemolysis.
• Reserve for lower (bladder) infection only — it does not achieve therapeutic tissue levels and is unsuitable for pyelonephritis or other upper urinary tract or systemic infection.
• Acute and chronic pulmonary reactions and hepatic and peripheral neuropathy adverse effects are recognised, particularly with prolonged use, so keep courses short.

Monitoring

For short treatment courses no routine monitoring is needed, but be alert to respiratory, hepatic and neurological adverse effects, especially in older patients or with repeated use.

Counselling the patient

• Take with food to improve absorption and reduce stomach upset, and complete the prescribed course.
• The medicine may turn your urine a dark yellow or brown colour, which is harmless.
• Report any new breathlessness, persistent cough, tingling in the hands or feet, or yellowing of the skin.

Evidence & guidelines

NICE guidance on urinary tract infection recommends nitrofurantoin as a first-line option for uncomplicated lower UTI when renal function is adequate.