Indications for: Isoniazid

Prophylaxis and treatment of susceptible tuberculosis.

Adult Dosage:

Prophylaxis: 300mg once daily. Active infection: 5mg/kg daily; max 300mg once daily. Do not interrupt therapy.

Children Dosage:

Prophylaxis: 10mg/kg once daily; max 300mg daily. Active infection: 10–20mg/kg once daily; max 500mg daily. Do not interrupt therapy.

Isoniazid Contraindications:

Drug-induced hepatitis. Previous isoniazid-associated hepatic injury. Severe adverse reactions to isoniazid (eg, drug fever, chills, arthritis). Acute liver disease of any etiology.

Isoniazid Warnings/Precautions:

Impaired renal or hepatic function. Monitor hepatic and ocular function. Alcoholism. Diabetes. Increased risk of liver damage with increasing age. Multiple drug therapy and concomitant pyridoxine may be necessary. Pregnancy. Nursing mothers.

Isoniazid Classification:

Isonicotinic acid.

Isoniazid Interactions:

Potentiates phenytoin. Alcohol increases risk of hepatitis. Pyridoxine deficiency increases risk of neuropathy.

Adverse Reactions:

Peripheral neuropathy (esp. in slow acetylators), elevated serum transaminases (SGOT; SGPT), bilirubinemia, bilirubinuria, jaundice, hepatitis (may be fatal), nausea, vomiting, epigastric distress, pancreatitis, blood dyscrasias, hypersensitivity reactions (eg, skin eruptions, TEN, DRESS), pyridoxine deficiency, hyperglycemia, pellagra, metabolic acidosis, gynecomastia, rheumatic syndrome, SLE-like syndrome.


Formerly known under the brand names INH, Laniazid.

How Supplied:

Contact supplier.