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Isoniazid and rifampin

Generic Name: isoniazid and rifampin (eye so NYE a zid and RIF am pin)
Brand Name: IsonaRif, Rifamate

Medically reviewed on January 15, 2018

What is isoniazid and rifampin?

Isoniazid and rifampin are antibiotics that fight bacteria.

Isoniazid and rifampin is a combination medicine used to treat tuberculosis (TB).

Isoniazid and rifampin may also be used for purposes not listed in this medication guide.

Important Information

You should not use isoniazid and rifampin if you have active liver disease (including hepatitis or cirrhosis), or a history of liver problems caused by taking isoniazid.

Serious and sometimes fatal liver problems may occur during treatment with isoniazid and rifampin or after you stop taking this medication, even months after stopping. The risk of liver problems is highest in adults between the ages of 35 and 65. Your liver function may need to be checked every month while you are taking isoniazid and rifampin.

Call your doctor right away if you have: nausea, upper stomach pain, loss of appetite, and unusual weakness or tiredness.

Avoid drinking alcohol. It may increase your risk of liver damage while you are taking isoniazid and rifampin.

Before taking this medicine

You should not use this medicine if you are allergic to isoniazid or rifampin, or if you have active liver disease (including hepatitis or cirrhosis), or a history of liver problems caused by taking isoniazid.

To make sure isoniazid and rifampin is safe for you, tell your doctor if you have:

  • liver disease;

  • kidney disease;

  • diabetes;

  • gout;

  • seizures; or

  • if you drink alcohol every day.

Serious and sometimes fatal liver problems may occur during treatment with isoniazid and rifampin or after you stop taking this medication, even months after stopping. The risk of liver problems is highest in adults between the ages of 35 and 65. Your liver function may need to be checked every month while you are taking this medicine.

It is not known whether isoniazid and rifampin will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

Isoniazid and rifampin can make birth control pills less effective. Ask your doctor about using non hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy while taking isoniazid and rifampin.

Isoniazid and rifampin can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How should I take isoniazid and rifampin?

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using isoniazid and rifampin.

Follow all directions on your prescription label. Do not take isoniazid and rifampin in larger or smaller amounts or for longer than recommended.

Take isoniazid and rifampin on an empty stomach, at least 1 hour before or 2 hours after a meal.

Isoniazid and rifampin may cause temporary discoloration of your teeth, sweat, urine, saliva, and tears (a yellow, orange, red, or brown color). This side effect is usually not harmful. However, soft contact lenses may be permanently stained if you wear them while taking isoniazid and rifampin.

Dark colored urine can be a sign of liver problems. Call your doctor if you have reddish-brown urine together with upper stomach pain, loss of appetite, and jaundice (yellowing of your skin or eyes).

Your doctor may have you take extra vitamin B6 while you are taking isoniazid and rifampin. Take only the amount of vitamin B6 that your doctor has prescribed.

Use this medication for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Isoniazid and rifampin will not treat a viral infection such as the common cold or flu.

Isoniazid and rifampin is usually given until lab tests show that the infection has cleared.

This medication can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using isoniazid and rifampin.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking isoniazid and rifampin?

Avoid wearing contact lenses. isoniazid and rifampin may discolor your tears, which could permanently stain soft contact lenses.

Avoid drinking alcohol. It may increase your risk of liver damage while you are taking isoniazid and rifampin.

Isoniazid and rifampin side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • nausea, upper stomach pain, feeling weak or tired, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

  • vision changes, confusion, hallucinations, unusual thoughts or behavior;

  • fever, unusual weakness, pale skin; or

  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin.

Common side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Isoniazid and rifampin dosing information

Usual Adult Dose for Tuberculosis -- Active:

2 capsules (300 mg isoniazid and 600 mg rifampin total dose) orally once a day on an empty stomach, either 1 hour before or 2 hours after ingestion of food or antacids.

Duration of Therapy: At least 4 months following the initial treatment phase; continue treatment longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV-positive.

Use: Treatment for pulmonary tuberculosis in which organisms are susceptible, and when the patient has been titrated on the individual components of this combination drug and thus, it has been established that the fixed dosage of this combination drug is therapeutically effective.

Usual Geriatric Dose for Tuberculosis -- Active:

Use with caution.

Usual Pediatric Dose for Tuberculosis -- Active:

Younger Than Age 15 Years: The ratio of isoniazid and rifampin in this combination drug may not be appropriate (e.g., pediatric patients usually receive higher mg/kg doses of isoniazid)

Age 15 Years and Older:
2 capsules (300 mg isoniazid and 600 mg rifampin total dose) orally once a day on an empty stomach, either 1 hour before or 2 hours after ingestion of food or antacids, following the initial treatment phase.

Duration of Therapy: At least 4 months following the initial treatment phase; continue treatment longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV-positive.

Use: Treatment for pulmonary tuberculosis in which organisms are susceptible, and when the patient has been titrated on the individual components of this combination drug and thus, it has been established that the fixed dosage of this combination drug is therapeutically effective.

What other drugs will affect isoniazid and rifampin?

Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete. Other drugs may interact with isoniazid and rifampin, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

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.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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