USES: This medication is used to prevent and treat tuberculosis.

HOW TO USE: This medication is injected into a muscle (IM) once daily or use as directed by your doctor. Do not stop using this medication without your doctor's approval. Stopping therapy too early may result in a relapse of the infection. Vitamin B6 (pyridoxine) may be prescribed to prevent numbness and tingling (neuropathy).

SIDE EFFECTS: May cause stomach upset, heartburn, nausea or dizziness. These effects should disappear as your body adjusts to the medication. If these effects persist or worsen, notify your doctor. Notify your doctor if you experience: blurred vision, dark urine, skin rash, yellowing of the eyes or skin, numbness or tingling of the hands or feet. In the unlikely event you have an allergic reaction to this drug, seek immediate medical attention. Symptoms of an allergic reaction include: rash, itching, swelling, dizziness, trouble breathing. If you notice other effects not listed above, contact your doctor or pharmacist.

PRECAUTIONS: Tell your doctor your medical history, especially of: kidney or liver problems, diabetes, a history of alcohol use, previous treatment for tuberculosis, allergies (especially drug allergies). Alcohol can reduce the effectiveness of isoniazid and increase side effects. Minimize alcohol consumption. This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor. Isoniazid is excreted into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Tell your doctor of all medications you may use (prescription and nonprescription), especially of: other MAO inhibitors (e.g., furazolidone, linezolid, moclobemide, phenelzine procarbazine, selegiline, isocarboxazid, tranylcypromine), adrenaline-like drugs (e.g., sympathomimetics such as ephedra, pseudoephedrine, phenylpropanolamine), serotonin-type drugs (including SSRI antidepressants and triptans such as sumatriptan), antacids that contain aluminum, disulfiram, phenytoin, rifampin, carbamazepine. In very rare cases, isoniazid (INH) may cause flushing of the skin or symptoms of high blood pressure such as unusually fast or slow heartbeat, vomiting, sweating, headache, chest pain, sudden vision changes, one-sided weakness or slurred speech. Tell your doctor immediately should these symptoms occur. If these reactions do occur, it is important that you follow special dietary restrictions in order to limit the amount of tyramine and histamine in your diet while you are taking this medicine. Foods and beverages high in tyramine should be avoided (see list below). Excessive amounts of coffee, chocolate, sour cream, or avocados may also produce symptoms of high blood pressure in very rare cases. High tyramine content foods include: aged cheeses (cheddar, camembert, emmenthaler, brie, stilton blue, gruyere, gouda, brick, bleu, roquefort, boursault, parmesan, romano, provolone, liederdranz, colby, edam), aged/dried/fermented/salted/smoked/pickled/processed meats and fish (includes bacon, summer sausage, liverwurst, hot dogs, corned beef, pepperoni, salami, bologna, ham, mortadella, pickled or dried herring), banana peel, beef and chicken liver (stored, not fresh), bouillon cubes, commercial gravies, concentrated yeast extracts (marmite), fava beans, Italian green beans, broad beans, fermented bean curd, homemade yeast-leavened bread, kim chee (Korean fermented cabbage), miso, orange pulp, overripe or spoiled fruits, packaged soups, red wine, sauerkraut, sherry, snow pea pods, sourdough bread, soy sauce, soya bean, soya bean paste, tap beer and ale, vermouth. Consult your healthcare professional (e.g., doctor, pharmacist, or dietician) for more information, including specific recommendations for your diet if necessary. This drug may interfere with the effectiveness of birth control pills. Discuss using other methods of birth control with your doctor. Isoniazid can cause false positive results in some diabetic urine testing products (cupric sulfate-type). Consult your doctor or pharmacist for recommendations. Do not start or stop any medicine without doctor or pharmacist approval.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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