Indications: urinary-tract infections

Caution anaemia; diabetes mellitus; electrolyte imbalance; vitamin B and folate deficiency; pulmonary disease; hepatic impairment; monitor lung and liver function on long-term therapy, especially in the elderly (discontinue if deterioration in lung function); susceptibility to peripheral neuropathy; false positive urinary glucose (if tested for reducing substances); urine may be coloured yellow or brown.

Contra-indications: renal impairment; infants less than 3 months old, G6PD deficiency (including pregnancy: at term, and breast-feeding: of affected infants, and porphyria

Side Effects: anorexia, nausea, vomiting, and diarrhoea; acute and chronic pulmonary reactions (pulmonary fibrosis; possible association with lupus erythematosus- like syndrome); peripheral neuropathy; hypersensitivity reactions (including angioedema, anaphylaxis, sialadenitis, urticaria, rash and pruritus); rarely, cholestatic jaundice, hepatitis, exfoliative dermatitis, erythema multiforme, pancreatitis, arthralgia, blood disorders (including agranulocytosis, thrombocytopenia, and aplastic anaemia), benign intracranial hypertension, and transient alopecia.

Dose: Acute uncomplicated infection, 50 mg every 6 hours with food for 7 days;

CHILD over 3 months, 3 mg/kg daily in 4 divided doses Severe chronic recurrent infection, 100 mg every 6 hours with food for 7 days (dose reduced or discontinued if severe nausea).

Prophylaxis, 50–100 mg at night; CHILD over 3 months, 1 mg/kg at night.

Pregnancy: Third trimester: May produce neonatal haemolysis if used at term.