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.
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.
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.
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:
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.
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:
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.
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.
NOTE:This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.
Remember, keep this and all other medicines out of the reach of children,
never share your medicines with others, and use this medication only for the indication prescribed.
