Indications: tuberculosis, in combination with other drugs; prophylaxis

Cautions: hepatic impairment; renal impairment; slow acetylator status (increased risk of side effects); epilepsy; history of psychosis; alcohol dependence, malnutrition, diabetes mellitus, HIV infection (risk of peripheral neuritis); pregnancy and breast-feeding; porphyria.

Contra-indications: drug-induced liver disease.

Side Effects: nausea, vomiting, constipation, dry mouth; peripheral neuritis with high doses (pyridoxine prophylaxis), optic neuritis, convulsions, psychotic episodes, vertigo; hypersensitivity reactions including fever, erythema multiforme, purpura; blood disorders including agranulocytosis, haemolytic anaemia, aplastic anaemia; hepatitis (especially over age of 35 years); systemic lupus erythematosus-like syndrome, pellagra, hyperreflexia, difficulty with micturition, hyperglycaemia, and gynaecomastia reported.

Dose: For 2 months initial and 4 months continuous phases: by mouth, pulmonary tuberculosis, 300mg daily on an empty stomach. Child, 5 mg/kg daily tuberculous meningitis, 10 mg/kg daily.