Isoniazid is a drug which action is directed against tuberculosis. The active substance with the same name has a devastating effect on germs – bacilli tuberculosis. Treatment with Isoniazid is standard for the infection, allowing you to destroy all forms of the pathogen, including, those that are in the stage of active multiplication. Also, this drug can be used for prevention, to maintain the health of adults and children, giving a positive Mantoux test, carriers of an inactive form of the disease.

Indications for use

  • Active tuberculosis, also tuberculous meningitis;
  • The prevention of tuberculosis;

Isoniazid is released in the form of tablets and solutions, which can be prescribed as intramuscular, intravenous injections and inhalation. Dosage, route of reception and duration of treatment are determined by the scheme chosen by the doctor. The instruction of the drug reports that the maximum adult daily dose is 300 mg. For small patients the amount of the drug is calculated from the weight.

Isoniazid is contraindicated in cases of

  • Epilepsy;
  • Transferred polio;
  • The propensity to seizures;
  • Diseases of the liver or kidneys;
  • Vascular diseases – atherosclerosis;
  • Although the drug penetrates through the placental barrier in breast milk, it can be given to pregnant and lactating women.

Side effects of Isoniazid

The reception of this anti-tuberculosis drug may cause headaches, dizziness. You will much less likely suffer from such unwanted symptoms as agitation, psychosis, insomnia and so on. It can also cause problems with digestion, until the liver damage.

In addition, there are complaints of heart pain, hormonal shifts that cause heavy menstrual bleeding and gynecomastia, the appearance of an allergic rash.

Drug interactions

When the drug is combined with paracetamol, rifampicin, it will increase the probability of development of hepatotoxicity, especially to patients with impaired liver function. In case of simultaneous reception the drug inhibits the metabolism of phenytoin and carbamazepine, it helps to improve their concentration in blood plasma and toxic effects.


Symptoms: dizziness, dysarthria, lethargy, disorientation, hyperreflexia, peripheral polyneuropathy, liver dysfunction, metabolic acidosis, hyperglycemia, glycosuria, ketonuria, seizures (in 1 to 3 h after the last drug reception), coma.


The drug should be used with caution in case of alcoholism, liver failure, kidney failure, seizures, decompensated diseases of the cardiovascular system (chronic heart failure, angina, hypertension), hypothyroidism.