Rifampin + Isoniazid


Generic Name: Rifampin + Isoniazid Brand Name(s): Generics only. No brands available.


What is Rifampin + Isoniazid used for?

Rifampin + Isoniazid is used to treat tuberculosis (TB). It contains 2 medications: rifampin and isoniazid. Both 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). Unnecessary use or misuse of any antibiotic can lead to its decreased effectiveness.

How should I take Rifampin + Isoniazid?

Take this product by mouth 1 hour before or 2 hours after a meal, usually once daily or as directed by your doctor.

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.

How do I store Rifampin + Isoniazid?

Rifampin + Isoniazid is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store Rifampin + Isoniazid in the bathroom or the freezer. There may be different brands of Rifampin + Isoniazid that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush Rifampin + Isoniazid down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using Rifampin + Isoniazid?

Before taking this product, tell your doctor or pharmacist if you are allergic to rifampin or isoniazid; 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, diabetes, 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 product passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

Is it safe during pregnancy or breast-feeding?

There are no adequate studies in women for determining risk when using this Rifampin + Isoniazid during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking Rifampin + Isoniazid. Rifampin + Isoniazid is pregnancy risk category C according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk,
  • B=No risk in some studies,
  • C=There may be some risk,
  • D=Positive evidence of risk,
  • X=Contraindicated,
  • N=Unknown

Side effects

What side effects can occur from Rifampin + Isoniazid?

Nausea/vomiting, upset stomach, heartburn, 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 serioussigns of kidney problems (such as change in the amount of urine, bloody urine), increased thirst/urination, vision changes, easy bruising/bleeding, mental/mood changes (such as confusion, psychosis), seizures.

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 products or narcotic pain 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, rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.


What drugs may interact with Rifampin + Isoniazid?

Some products that may interact with this drug include: acetaminophen, carbamazepine, disulfiram, 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, tacrolimus, theophylline, certain anti-infectives (e.g., 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 tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

Rifampin + Isoniazid may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Does food or alcohol interact with Rifampin + Isoniazid?

Rifampin + Isoniazid may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with Rifampin + Isoniazid?

Rifampin + Isoniazid may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.


The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using this Rifampin + Isoniazid.

What is the dose of Rifampin + Isoniazid for an adult?

Usual Adult Dose for Tuberculosis – Active

2 capsules (300 mg isoniazid and 600 mg rifampin total dose) orally once a day on an empty stomach, either 1 hour before or 2 hours after ingestion of food or antacids.

Duration of Therapy: At least 4 months following the initial treatment phase; continue treatment longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV-positive.

Use: Treatment for pulmonary tuberculosis in which organisms are susceptible, and when the patient has been titrated on the individual components of this combination drug and thus, it has been established that the fixed dosage of this combination drug is therapeutically effective.

Usual Geriatric Dose for Tuberculosis – Active

Use with caution.

Renal Dose Adjustments

No adjustment recommended; however, carefully monitor use in patients with severe renal dysfunction.

Liver Dose Adjustments

-Severe Hepatic Damage; Acute Liver Disease of Any Etiology: Contraindicated.

-Impaired Liver Function: Use with caution and under strict medical supervision.

Comments: If this drug is given to patients with impaired liver function, carefully monitor liver function (especially SGPT and SGOT) prior to therapy, then every 2 to 4 weeks during therapy; withdraw treatment if signs of hepatocellular damage occur.

Other Comments

Administration Advice:

-Concomitant administration of pyridoxine (Vitamin B6) is recommended in the malnourished, in those predisposed to neuropathy (e.g., alcoholics and diabetics), and in adolescents.

Storage Requirements:

-Store at 25 degrees Celsius/77 degrees Fahrenheit; excursions permitted to 15 to 30 degrees C/59 to 86 degrees F.

-Protect from moisture and excessive humidity.


-This fixed-dosage combination drug (150 mg isoniazid and 300 mg rifampin per capsule) is not recommended for initial therapy of tuberculosis or for preventive therapy.

-This drug is not indicated for the treatment of meningococcal infections or asymptomatic carriers of Neisseria meningitis to eliminate meningococci from the nasopharynx.


DERMATOLOGIC: Skin reactions (e.g., signs/symptoms of progressive skin rash often with blisters or mucosal lesions)


-Baseline measurements of serum creatinine, complete blood count, platelet count, and blood uric acid.

-Carefully monitor use of this drug in patients with chronic liver disease, severe renal dysfunction, slow acetylator status, epilepsy, history of psychosis, history of peripheral neuropathy, diabetes, alcohol dependence, HIV infection, or porphyria.

-Evaluate patients at least monthly during treatment, and specifically question them about symptoms associated with adverse reactions.

-Follow-up with all patients with abnormalities, including laboratory testing if necessary.

HEPATIC: Baseline measurements of liver function (e.g., hepatic enzymes, bilirubin)

OCULAR: Ophthalmologic exams including ophthalmoscopy (before treatment initiation and periodically thereafter)

OTHER: Collect specimens (bacteriologic smears or cultures) for identification of the infecting organism and to confirm the susceptibility of the organism to rifampin and isoniazid prior to treatment initiation; repeat throughout therapy.

Patient Advice:

-This drug may cause side effects such as vertigo, vision problems, and psychotic reactions; avoid potentially dangerous activities such as driving and operating machinery until you know how this drug affects you.

What is the dose of Rifampin + Isoniazid for a child?

Usual Pediatric Dose for Tuberculosis – Active

Younger Than Age 15 Years: The ratio of isoniazid and rifampin in this combination drug may not be appropriate (e.g., pediatric patients usually receive higher mg/kg doses of isoniazid)

Age 15 Years and Older:

2 capsules (300 mg isoniazid and 600 mg rifampin total dose) orally once a day on an empty stomach, either 1 hour before or 2 hours after ingestion of food or antacids, following the initial treatment phase.

Duration of Therapy: At least 4 months following the initial treatment phase; continue treatment longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV-positive.

Use: Treatment for pulmonary tuberculosis in which organisms are susceptible, and when the patient has been titrated on the individual components of this combination drug and thus, it has been established that the fixed dosage of this combination drug is therapeutically effective.


Safety and efficacy have not been established in patients younger than 15 years.

How is Rifampin + Isoniazid available?

Rifampin + Isoniazid is available in the following dosage forms and strengths:

  • Oral capsule.

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of Rifampin + Isoniazid, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: April 21, 2018 | Last Modified: April 21, 2018

You might also like