Generic Name: isoniazid, Oral tablet

All Brands

SECTION 1 of 4

Highlights for isoniazid

Oral tablet
1
ISONIAZID (eye soe NYE a zid) is used to prevent or to treat tuberculosis (TB).
2
This drug also comes in other forms, including Oral SolutionParenteral Solution
3 4 5
Talk to your healthcare provider if you have any of these conditions.
6
Know what to watch for and get tips for reducing your risks while taking this drug.
SECTION 2 of 4

isoniazid Side Effects

Oral tablet

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
SECTION 3 of 4

isoniazid May Interact with Other Medications

Oral tablet

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
SECTION 4 of 4

How to Use isoniazid

Oral tablet

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. Take your medicine at regular intervals. Do not take your medicine more often than directed. For your therapy to work as well as possible, take each dose exactly as prescribed. Do not skip doses or stop your medicine even if you feel better. 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. Special care may be needed.

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
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 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.

Where should I keep my medicine?

Keep out of the reach of children.

Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.

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Last Updated: January 5, 2009

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