• Basic Info
• Top Questions
• Clinical Info

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

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

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What is the price of this medication and similar alternatives?

This pricing information is subject to change at the sole discretion of DS Pharmacy. This pricing information was updated 09/2009. For the most current and up-to-date pricing information, please visit www.drugstore.com. Actual costs to patients will vary depending on the use of specific retail or mail-order locations and health insurance copays.

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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

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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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. 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.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
NOTE: This medicine is only for you. Do not share this medicine with others.

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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.

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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

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

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Who should NOT use this medication?

• History of severe hypersensitivity reactions, including drug-induced hepatitis.
• History of isoniazid-associated hepatic injury.
• History of severe adverse reactions to isoniazid (e.g., drug fever, chills, arthritis).
• Acute liver disease of any etiology.

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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.

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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

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Can I stop taking the medication if I feel better?
If you have been diagnosed with a disease for which an antibiotic is needed, you must complete the prescribed course of treatment. Even if you start to feel better, do not skip any doses and remember to take the medication until it is all gone.

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I am on so many medications; do I have to take them all?
This is called polypharmacy—many different medications being used at the same time by one person. Sometimes, being on multiple medications is acceptable and appropriate but at other times it may be problematic. If you are receiving your medications from multiple physicians you need to ensure that they all know what medications you are taking. The best way to do this is to make a list of all the medications you are currently using, including all nutritional supplements, homeopathic remedies, vitamins and over-the-counter drugs (if possible, also include all the diseases you have been diagnosed with). Give a copy to every doctor who takes care of you so they have it on file, this way they can avoid duplicating medications and perhaps even try to consolidate some. After every doctor's visit remember to update the list accordingly. Also, as much as you possibly can, try to use the same pharmacy to fill all your prescriptions, this way any potential drug interactions can be caught and averted.

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Where can I get more information?
More Information

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