Common Brand Name(s): Rifater
Important: How To Use This Information
This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.
Isoniazid has rarely caused very serious (possibly fatal) liver disease. The risk of liver disease is increased in people who are 35 years and older, who use alcohol or illegal injection drugs, or who currently have long-term liver problems. Tell your doctor right away if you develop symptoms of liver disease, including persistent nausea/vomiting, severe stomach/abdominal pain, unusual weakness/tiredness, dark urine, yellowing eyes/skin.
Your doctor should order liver function tests while you are taking this medication. Keep all medical and laboratory appointments.
This product is used to treat tuberculosis (TB) of the lungs. It contains 3 medications: rifampin, isoniazid, and pyrazinamide. These medications are antibiotics. Rifampin is known as a rifamycin antibiotic. This product works by stopping the growth of bacteria.
This antibiotic treats only bacterial infections. It will not work for viral infections (such as common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections.
How To Use
Take this product by mouth 1 hour before or 2 hours after a meal, usually once daily or as directed by your doctor. Take it with a full glass of water (8 ounces/240 milliliters) unless your doctor directs you otherwise.
If you also take antacids, take this medication at least 1 hour before the antacid.
The dosage is based on your age, weight, medical condition, and response to treatment.
For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day.
Continue to take this medication (and other TB medications) until the full prescribed amount is finished, even if symptoms disappear. Stopping the medication too early or skipping doses may allow the bacteria to continue to grow, which may result in a return of the infection and cause the infection to be more difficult to treat (resistant).
Your doctor may also direct you to take vitamin B6 (pyridoxine) to help prevent certain side effects (such as nerve problems) from isoniazid. Follow your doctor's instructions carefully.
Isoniazid may interact with foods containing tyramine/histamine (such as cheese, red wine, certain types of fish). This interaction may cause increased blood pressure, flushing of the skin, headache, dizziness, or fast/pounding heartbeat. Tell your doctor right away if any of these symptoms occur. Your doctor may recommend that you follow a special diet while taking this medication. Consult your doctor for more details.
Tell your doctor if your condition persists or worsens.
See also Warning section.
Nausea/vomiting, upset stomach, heartburn, mild muscle/joint pain, or headache may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
This medication may cause urine, sweat, saliva, or tears to change color (yellow, orange, red, or brown). This effect is harmless and will go away when the medication is stopped. However, teeth and contact lens staining may be permanent.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if any of these unlikely but serious side effects occur:
- numbness/tingling of arms/legs
- painful/swollen joints
Tell your doctor right away if any of these rare but serious side effects occur:
- signs of kidney problems (such as change in the amount of urine, bloody urine)
- increased thirst/urination
- vision changes
- fast heartbeat
- easy bruising/bleeding
- mental/mood changes (such as confusion, psychosis)
This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Do not use anti-diarrhea or opioid medications if you have any of the following symptoms because these products may make them worse. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:
- fever that doesn't go away
- new or worsening lymph node swelling
- itching/swelling (especially of the face/tongue/throat)
- severe dizziness
- trouble breathing
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
See also Warning section.
Before taking this product, tell your doctor or pharmacist if you are allergic to rifampin, isoniazid, or pyrazinamide; or to other rifamycins (such as rifabutin, rifapentine); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of:
- previous severe reaction from isoniazid (such as liver disease)
- liver disease
- kidney disease
- alcohol use
- HIV infection
- high uric acid level in the blood
- numbness/tingling of arms/legs (peripheral neuropathy)
- recent childbirth
- a certain blood disorder (porphyria)
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
Alcohol may increase the risk of liver disease. Avoid alcoholic beverages while using this medication.
This product may cause live bacterial vaccines (such as typhoid vaccine) to not work as well. Do not have any immunizations/vaccinations while using this medication unless your doctor tells you to.
During pregnancy, this product should be used only when clearly needed. When rifampin is taken during the last few weeks of pregnancy, the risk of bleeding in both mother and infant may be increased. Tell your doctor right away if you notice any bleeding in your newborn. Discuss the risks and benefits with your doctor.
This medication passes into breast milk but the effect on a nursing infant is unknown. Discuss the risks and benefits with your doctor before breast-feeding.
See also How to Use section.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some products that may interact with this drug include:
- MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine)
- SSRI antidepressants (such as fluoxetine, sertraline)
- valproic acid
Rifampin can speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include digoxin, nimodipine, phenytoin, ranolazine, praziquantel, tacrolimus, theophylline, certain anti-infectives (including chloramphenicol, clarithromycin, dapsone, doxycycline, linezolid, telithromycin, zidovudine, quinolones such as ciprofloxacin), azole antifungals (such as itraconazole, ketoconazole), "blood thinners" (such as warfarin), calcium channel blockers (such as diltiazem, verapamil), HIV NNRTIs (such as delavirdine, etravirine, nevirapine), HIV protease inhibitors (such as atazanavir, ritonavir, saquinavir), among others.
This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use additional reliable birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.
This medication may interfere with certain laboratory tests (including folate/vitamin B12 levels, urine glucose/ketone tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.
If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: severe stomach/abdominal pain, unusual tiredness/weakness, yellowing eyes/skin, vision changes, slow/shallow breathing, severe drowsiness.
Do not share this medication with others.
Laboratory and/or medical tests (such as sputum test, kidney/liver function, bilirubin levels, uric acid levels, complete blood count) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.
For the best possible benefit, it is important to take each scheduled dose of this medication as directed. If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.
Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.
Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised November 2019.
Copyright(c) 2019 First Databank, Inc.
Conditions of use: The information in this database is intended to supplement, not substitute for the expertise and judgment of healthcare professionals. The information in not intend to cover all possible uses, directions, precautions, drug interactions or adverse effects nor should it be construed in indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.