Isoniazid and Rifampin

Isoniazid and Rifampinis are combination medications used for the treatment of tuberculosis (TB). 

• Isoniazid and Rifampin are available under various brand names: IsonaRif, Rifamate

Common side effects of Isoniazid and Rifampin include:

• the red-orange coloration of tears, sweat, saliva, urine, or stools.
• numbness, tingling, itching, mild rash.
• drowsiness, dizziness, headache.
• muscle pain or weakness.
• heartburn, gas, diarrhea; or
• mouth pain.

Serious side effects of Isoniazid and Rifampin include:

• hives. 
• difficult breathing. 
• swelling of the face, lips, tongue, or throat.
• nausea, upper stomach pain, feeling weak or tired, loss of appetite, dark urine, clay-colored stools, and 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 the skin.

Rare side effects of Isoniazid and Rifampin include:

• none

Seek medical care or call 911 at once if you have the following serious side effects:

• Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors.
• Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights.
• Serious heart symptoms such as fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

Adult dosage

Capsule

• 300 mg/150 mg

Tuberculosis

Adult dosage

• Rifampin 600 mg/isoniazid 300 mg (i.e., 2 capsules) orally once daily. 

Dosage Considerations – Should be Given as Follows: 

• See “Dosages”

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first

• Isoniazid and Rifampin have severe interactions with at least 55 other drugs.
• Isoniazid and Rifampin have serious interactions with at least 272 other drugs.
• Isoniazid and Rifampin have moderate interactions with at least 452 other drugs.
• Isoniazid and Rifampin have minor interactions with at least 133 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

Contraindications

• Allergic to isoniazid or rifampin 
• active liver disease (including hepatitis or cirrhosis), or 
• a history of liver problems caused by taking isoniazid.

Effects of drug abuse

• None

Short-Term Effects

• See “What Are Side Effects Associated with Using Isoniazid and Rifampin?”

Long-Term Effects

• See “What Are Side Effects Associated with Using Isoniazid and Rifampin?”

Cautions

• 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 this medicine.
• 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.
• 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.
• Avoid wearing contact lenses. This medicine 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.

Pregnancy and Lactation

• 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 nonhormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy while taking isoniazid and rifampin.

Lactation

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