Isoniazid and rifampin are antibiotics. They prevent tuberculous bacteria from multiplying in your body.

Isoniazid and rifampin are used together to treat tuberculosis (TB).

Isoniazid and rifampin may also be used for purposes other than those listed in this medication guide.

Take all of the isoniazid and rifampin that has been prescribed for you even if you begin to feel better. Your symptoms may begin to improve before the infection is completely treated.

Avoid alcohol while taking isoniazid and rifampin. Alcohol will increase the risk of damage to your liver during treatment with this medication.

Call your doctor immediately if you experience a fever, chills, a sore throat, muscle and bone pain, a headache, excessive tiredness or weakness, numbness or tingling in your hands or feet, loss of appetite, nausea and vomiting, yellowing of your skin or eyes, darkening of your urine, unusual bleeding or bruising, a rash, or itching.

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

This medication may decrease the effectiveness of birth control pills. Talk to your doctor about using another form of birth control during treatment.

Before taking this medication, tell your doctor if you have

• ever had an allergic reaction to isoniazid or rifampin;

• disease;

• liver disease; or

• porphyria.

You may not be able to take isoniazid and rifampin, or you may require a lower dose or special monitoring during treatment if you have any of the conditions listed above.

It is not known whether isoniazid and rifampin will harm an unborn baby. Do not take this medication without first talking to your doctor if you are pregnant.

It is also not known whether isoniazid and rifampin will harm a nursing baby. Do not take this medication without first talking to your doctor if you are breast-feeding a baby.