ISONIAZID

also called isonicotinic acid hydrazide (INH) drug used in the chemotherapy of tuberculosis in combination with other drugs, such as rifampin, ethambutol, or streptomycin; these drugs are used with isoniazid in order to prevent, or at least delay, the development of isoniazid-resistant strains of the infective agents, tuberculin bacilli. Treatment usually is continued for many months. The most important drug in the therapy of tuberculosis, isoniazid was introduced into medicine in 1952; it usually is administered orally, but it can be given by injection. It may cause dizziness or headache, but side effects are not common.