• Basic Info
• Top Questions
• Interactions

Before taking isoniazid/pyrazinamide/rifampin, tell your doctor if you are taking any of the following drugs:

• antacids. Aluminum salts will decrease the action of isoniazid. Do not take antacids that contain aluminum for 1 to 2 full hours before or after taking a dose of isoniazid.

• allopurinol (Zyloprim). The effects of allopurinol may be decreased by pyrazinamide.

• ketoconazole (Nizoral), itraconazole (Sporanox), or fluconazole (Diflucan). Isoniazid/pyrazinamide/rifampin may decrease the action of the antifungal medicines. Therefore, a fungal infection may not be adequately treated.

• disulfiram (Antabuse). Unusual behavior and coordination difficulties may occur if these medicines are taken together.

Isoniazid may increase the effects of the following medicines:

• warfarin (Coumadin);

• carbamazepine (Tegretol);

• theophylline (Theo-Dur, Theochron, Theolair, Slo-Phyllin, Elixophyllin);

• ethionamide (Trecator-SC);

• cycloserine (Seromycin);

• phenytoin (Dilantin), ethotoin (Peganone), and mephenytoin (Mesantoin).

• meperidine (Demerol); and

• benzodiazepines such as alprazolam (Xanax), diazepam (Valium), lorazepam (Ativan), and temazepam (Restoril).

Before taking isoniazid/pyrazinamide/rifampin, tell your doctor if you are taking any of the medicines listed above.

Rifampin may decrease the effects of the following drugs:

• acetaminophen (Tylenol, others);

• blood thinners such as warfarin (Coumadin);

• barbiturates such as phenobarbital (Luminal, Solfoton), amobarbital (Amytal), secobarbital (Seconal), and butabarbital (Butisol);

• benzodiazepines such as alprazolam (Xanax), diazepam (Valium), and temazepam (Restoril);

• beta-blockers such as atenolol (Tenormin), propranolol (Inderal), and metoprolol (Lopressor);

• heart medicines such as digoxin (Lanoxin), disopyramide (Norpace), quinidine (Quinora, Quinidex, Cardioquin, others), mexiletine (Mexitil), tocainide (Tonocard), verapamil (Calan, Verelan, Isoptin), and enalapril (Vasotec);

• corticosteroids such as prednisone (Deltasone, Orasone, Meticorten), prednisolone (Delta Cortef, Prelone, others), methylprednisolone (Medrol), and betamethasone (Celestone);

• sulfonylureas such as glipizide (Glucotrol), glyburide (Micronase, Diabeta, Glynase), chlorpropamide (Diabinese), tolbutamide (Orinase), and tolazamide (Tolinase);

• HIV and AIDS medicines such as zidovudine (Retrovir), delavirdine (Rescriptor), saquinavir (Invirase), ritonavir (Norvir), indinavir (Crixivan), and nelfinavir (Viracept);

• sulfa medicines such as sulfamethoxazole (Bactrim, Septra, Gantanol, Azo-Gantanol), and sulfisoxazole (Gantrisin, Azo-Gantrisin);

• estrogens such as Premarin, Ogen, Estrace, Menest, Estratab, Ortho-Est, and others;

• oral birth control pills such as Triphasil, Ortho-Novum, Ortho-Cyclen, Ortho-Tri-Cyclen, Ovral, Lo/Ovral, Desogen, Nordette, Levora, Levlen, Tri-Levlen, Nelova, Norinyl, Brevicon, Ovcon, Loestrin, Demulen, and others;

• phenytoin (Dilantin), ethotoin (Peganone), and mephenytoin (Mesantoin);

• theophylline (Theolair, Theo-Dur, Theochron, Theo-Bid, others);

• methadone (Dolophine);

• clofibrate (Atromid-S); and

• cyclosporine (Sandimmune, Neoral).

Pyrazinamide may affect the Acetest and Ketostix urine tests for ketones. This reaction can cause a pink-brown color to appear.

Drugs other than those listed here may also interact with isoniazid/pyrazinamide/rifampin. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.

If you experience any of the following serious side effects, stop taking isoniazid/pyrazinamide/rifampin and seek emergency medical attention or contact your doctor immediately:

• an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);

• excessive tiredness or weakness;

• nausea, vomiting, diarrhea, or loss of appetite;

• yellow skin or eyes;

• unusual bruising or bleeding;

• dark urine;

• little or no urine;

• difficult or painful urination;

• numbness or tingling in your hands or feet;

• muscle or bone pain;

• painful or swollen joints;

• worsening gout;

• seizures;

• blurred vision;

• fever, chills, or a sore throat;

• a headache;

• a rash or itching; or

• confusion or abnormal behavior.

Other, less serious side effects may be more likely to occur. Continue to take isoniazid/pyrazinamide/rifampin and talk to your doctor if you experience

• red-orange coloration of tears, sweat, saliva, urine, or feces; or

• mild tiredness or weakness.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome.