Drugs A - Z

Isoniazid Oral solution

It is used to prevent or to treat tuberculosis.

Generic Name: isoniazid  |  Brand Name: Nydrazid

Brand Names: Nydrazid

There is an FDA Alert for this drug. Click here to view it.

  • Severe and sometimes fatal hepatitis reported; hepatitis usually develops during the first 3 months of therapy but may develop after many months.
  • Risk of developing hepatitis is age related. Approximate case rates by age are: <1 per 1000 in individuals <20 years of age; 3 per 1000 in individuals 20–34 years of age; 12 per 1000 in individuals 35–49 years of age; 23 per 1000 in individuals 50–64 years of age; 8 per 1000 in individuals >65 years of age.
  • Risk of hepatitis is increased by daily consumption of alcohol, chronic liver disease, and use of illicit injection drugs.
  • There may be an increased risk of fatal hepatitis in women, particularly black and Hispanic women. Risk also may be increased during the postpartum period.
  • Precise data on fatality rate for isoniazid-related hepatitis not available. There were 8 deaths among 174 cases of hepatitis in a US Public Health Service Surveillance Study that included 13,838 individuals.
  • Monitor and interview patients at monthly intervals. In addition, determine AST and ALT concentrations at baseline and periodically (monthly or more frequently as needed) in individuals ≥35 years of age and in individuals at increased risk of hepatitis.
  • Increases in serum transaminase concentrations occur in 10–20% of patients; these increases usually occur during the first few months of therapy but can occur at any time. Enzyme concentrations usually return to pretreatment values despite continued isoniazid therapy, but progressive liver dysfunction occurs in some cases.
  • Consider discontinuing isoniazid if liver function abnormalities are >3–5 times ULN.
  • Liver function tests are not a substitute for monthly clinical evaluations or for prompt assessment of signs or symptoms of adverse reactions that may occur between regularly scheduled evaluations.
  • Patients should be advised to immediately report prodromal symptoms of hepatitis to their clinician. (See Advice to Patients.)
  • Discontinue immediately if symptoms or signs suggestive of hepatic damage are detected; continued isoniazid use has been reported to cause a more severe form of liver damage.
  • Patients who have signs or symptoms of isoniazid-associated hepatic damage should be treated using alternative antituberculosis agents. If use of isoniazid is considered necessary, the drug should be restarted only after symptoms and laboratory abnormalities have cleared. In this situation, isoniazid should be restarted in very small dosages and gradually increased; discontinue immediately if there is any indication of recurrent liver involvement.
  • Use of isoniazid for treatment of latent tuberculosis infection (LTBI) should be deferred in patients with acute hepatic disease.

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


Last Updated: May 05, 2009
Licensed from
The Healthline Site, its content, such as text, graphics, images, search results, HealthMaps, Trust Marks, and other material contained on the Healthline Site ("Content"), its services, and any information or material posted on the Healthline Site by third parties are provided for informational purposes only. None of the foregoing is a substitute for professional medical advice, examination, diagnosis, or treatment. Always seek the advice of a physician or other qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on the Healthline Site. If you think you may have a medical emergency, call your doctor or 911 immediately. Please read the Terms of Service for more information regarding use of the Healthline Site.
Advertisement