Tuberculosis Medicine - Isoniazid
What is INH?
Isoniazid (INH) is an antibiotic medicine used to treat tuberculosis (TB) disease and latent TB infection. There are two ways it can be used.
- To treat latent TB infection:
Most people who breathe in TB germs are able to stop them from growing. Their immune system traps the TB germs and keeps them inactive. This is called latent TB infection. To treat latent TB infection, the medication is usually taken for nine months.
- To cure TB disease (when taken with other medications):
TB germs become active when the body's immune system is no longer able to contain the infection and stop the germs from growing. Your doctor will determine how many months you will take medicine to cure TB disease.
Things to remember when taking this medicine:
- Take your medicine at the same time every day (i.e., before going to bed or first thing in the morning).
- INH is more effective if taken on an empty stomach. However, if you experience stomach problems, you may take it with food.
- If you find this drug causes fatigue, take it at bedtime. Fatigue can occur within the first month, but lessens as your body gets used to the drug.
- Do not stop taking your medicine unless your health care professional tells you to do so.
- If you miss a dose, take it as soon as possible, but never take two doses at one time.
- If you are taking other prescription or over-the-counter medicines, please discuss this with your health care professional to help avoid any serious drug interactions.
- Do not drink alcohol while taking this medicine. You could damage your liver. If this is not possible, limit your intake to one to two drinks per week.
- Tell your doctor if you have or have ever had liver disease.
- Tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking INH, call your doctor.
- Store INH in a cool, dry place, out of reach of children.
Side effects to watch for:
- Most people have no problems while taking INH.
- Occasional side effects include skin rash, diarrhea, poor appetite, and a "pins and needles" feeling in your fingers and toes (contact your health care professional to receive Vitamin B6, which will help prevent this "pins and needles").
If you have any of the following more serious side effects, stop taking the medicine and call your health care professional:
- nausea or vomiting
- stomach cramps or pain or tenderness in the stomach area
- very dark urine
- yellowish skin or eyes
- light-coloured bowel movements
- fever for three days or more
- fatigue or feeling very tired
Remember:
You must keep your appointments at the TB clinic, KFL&A Public Health or your doctor's office to be monitored regularly while on this medicine.
Call KFL&A Public Health at least two weeks before you need more medicine. Arrangements will be made for a refill of your prescription. All TB medications are free of charge.
If you have questions or concerns, please call KFL&A Public Health at 613-549-1232 or 1-800-267-7875, ext. 1287.
Revised: 2014-07-16