Revised: Nov. 2016

Medication Information

Isoniazid (INH) is an antibiotic medicine.  There are two ways that it is used:

  • To treat inactive latent tuberculosis (TB)
  • To cure active tuberculosis disease in combination with other medicines

The TB germs are very strong and are hard to get rid of. You will need to take this medicine for 6 to 12 months in order to kill all the TB bacteria. Your doctor will decide how many months you will need to take the medicine.

Taking the Medication

  • Take this medicine as directed by your doctor.
  • Even if you start to feel better, it is important to keep taking this medicine until the doctor tells you to stop.
  • This medicine works best on an empty stomach. However, if it upsets your stomach you may take it with food.
  • Your doctor may ask you to take vitamin B6 (Pyridoxine). Vitamin B6 helps prevent numbness and tingling in your fingers and toes which may be caused by Isoniazid. You may not need to take vitamin B6 if you are able to get enough in your daily meals.

Possible Side Effects

Most people do not experience problems while taking INH. You will need to be monitored regularly by your doctor while taking INH.

  • Numbness or tingling in fingers or toes
  • Skin rash
  • Nausea, vomiting
  • Stomach pain
  • Tiredness, weakness
  • Yellow skin or eyes
  • Loss of appetite
  • Very dark urine

*If you have any of these side effects speak with your doctor immediately. If you are unable to reach your doctor, stop taking the medicine until you do speak with your doctor.

Precautions

  • Do not drink alcohol. Drinking alcohol can increase the chance of liver problems while you are taking Isoniazid.
  • Safe for use in pregnancy and breastfeeding
  • Talk to your doctor about other medicines you are taking or any new medicines that you start taking.
  • If you take aluminum antacids, take isoniazid at least 1 hour before taking the antacid.
  • If you miss a dose, take it as soon as possible. If it is almost time to take your next dose, do not take the missed dose. Do not take 2 doses at the same time.
  • Store the medicine at room temperature in a cool, dry place. Do not put it in the refrigerator.

Special Populations

  • Safe for use in pregnancy and breastfeeding
  • Talk to your doctor about other medicines you are taking or any new medicines that you start taking.
  • If you take aluminum antacids, take isoniazid at least 1 hour before taking the antacid.
  • If you miss a dose, take it as soon as possible. If it is almost time to take your next dose, do not take the missed dose. Do not take 2 doses at the same time.
  • Store the medicine at room temperature in a cool, dry place. Do not put it in the refrigerator.

Drug Interactions

  • Talk to your doctor about other medicines you are taking or any new medicines that you start taking.
  • If you take aluminum antacids, take isoniazid at least 1 hour before taking the antacid.
  • If you miss a dose, take it as soon as possible. If it is almost time to take your next dose, do not take the missed dose. Do not take 2 doses at the same time.
  • Store the medicine at room temperature in a cool, dry place. Do not put it in the refrigerator.

Missed Doses

  • If you miss a dose, take it as soon as possible. If it is almost time to take your next dose, do not take the missed dose. Do not take 2 doses at the same time.

Storage

  • Store the medicine at room temperature in a cool, dry place. Do not put it in the refrigerator.