isoniazid (generic name)

It is used to prevent or to treat tuberculosis.
(eye soe NYE a zid)
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What is this medicine?

ISONIAZID (eye soe NYE a zid) is used to prevent or to treat tuberculosis.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
  • diabetes
  • HIV positive
  • if you frequently drink alcohol-containing beverages
  • kidney disease
  • liver disease
  • malnutrition
  • tingling of the fingers or toes, or other nerve disorder
  • an unusual or allergic reaction to isoniazid, other medicines, foods, dyes or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. Take this medicine on an empty stomach, at least 30 minutes before or 2 hours after food. Do not take with food. Use a specially marked spoon or container to measure each dose. Ask your pharmacist if you do not have one. Household spoons are not accurate. Take your medicine at regular intervals. Do not take it more often than directed. Take all of your medicine as directed even if you think you are better. Do not skip doses or stop your medicine early. Skipping doses may make the TB resistant to this medicine and other medicines. Do not stop taking except on your doctor's advice.

Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
  • entacapone
  • green tea
  • levodopa
  • MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate
  • procarbazine
  • ranolazine
  • tolcapone

This medicine may also interact with the following medications:

  • acetaminophen
  • alcohol
  • antacids
  • medicines for diabetes
  • medicines for fungal infections like ketoconazole and itraconazole
  • medicines for seizures like carbamazepine, phenobarbital, phenytoin, valproic acid
  • theophylline
  • zalcitabine

What should I watch for while using this medicine?

Visit your doctor or health care professional for regular check ups. You will need blood work done regularly.

You may need to take vitamin supplements while on this medicine. Talk to your doctor about the foods you eat and the vitamins you take. Avoid antacids for 2 hours before and after taking a dose of this medicine.

Alcohol may interfere with the effect of this medicine. Avoid alcoholic drinks.

If you are diabetic check your blood sugar as directed. Also, you may get a false-positive result for sugar in your urine. Talk with your doctor.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
  • allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
  • breathing problems
  • changes in vision or eye pain
  • dark urine
  • fever, sore throat
  • hallucination, loss of contact with reality
  • loss of appetite
  • memory problems
  • nausea, vomiting
  • pain, tingling, numbness in the hands or feet
  • redness, blistering, peeling or loosening of the skin, including inside the mouth
  • seizures
  • stomach pain
  • unusually weak or tired
  • yellowing of the eyes or skin

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • breast enlargement or tenderness
  • diarrhea
  • headache
  • upset stomach
  • trouble sleeping

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Last Updated: May 05, 2009
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