Prescription under medical supervision

Therapeutic action

– First line antituberculous antibacterial (bactericidal activity)


– Treatment of tuberculosis, in combination with other antituberculous antibacterials
– Prophylaxis of tuberculosis

Forms and strengths

– 100 mg and 300 mg tablets
– 50 mg/5 ml oral solution


– Child under 30 kg: 10 mg/kg (7 to 15 mg/kg) once daily, on an empty stomach
– Child over 30 kg and adult: 5 mg/kg (4 to 6 mg/kg) once daily, on an empty stomach
– Do not exceed 300 mg daily.


– According to protocol

Contra-indications, adverse effects, precautions

– Do not administer to patients with severe hepatic impairment.
– May cause:
• peripheral neuropathy, especially in malnourished, alcoholic, diabetic, HIV-infected patients; pregnant and breast-feeding women; patients with renal impairment or chronic hepatic disease and patients receiving high doses of isoniazid;
• hepatic disorders (jaundice), especially in alcoholic patients, patients receiving rifampicin, patients > 35 years;
• hypersensitivity reactions, psychotic reactions.
– If signs of hepatotoxicity (e.g. jaundice) develop, isoniazid should be discontinued until symptoms resolve.
– Administer with caution and closely monitor patients taking phenytoin, carbamazepine, benzodiazepines (risk of toxicity), warfarin (risk of bleeding), cycloserine (increased risk of peripheral neuropathy).
– Administer pyridoxine (vitamin B6) in patients at risk of peripheral neuropathy (child: 5 mg daily; adult: 10 mg daily).
– Pregnancy: no contra-indication
– Breast-feeding: no contra-indication; supplement the infant with pyridoxine (5 mg daily).


– Prophylactic treatment should be considered only after excluding active tuberculosis.
– For patients sensitive to first-line antituberculous treatment, isoniazid is given as part of a fixed dose combination (isoniazid+rifampicin+pyrazinamide+ethambutol or isoniazid+rifampicin+pyrazinamide or isoniazid+rifampicin).
  Storage: below 25 °C -  -