Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 5/25/2022
Rifamate Side Effects Center

What Is Rifamate?

Rifamate (rifampin and isoniazid) is a combination of two antibiotics used to treat tuberculosis.

What Are Side Effects of Rifamate?

Common side effects of Rifamate include:

Other side effects of Rifamate include:

  • allergic reactions
  • nausea
  • vomiting
  • diarrhea
  • loss of appetite
  • yellow skin or eyes
  • unusual bruising or bleeding
  • dark urine
  • little or no urine
  • numbness or tingling in your hands or feet
  • muscle or bone pain
  • seizures
  • blurred vision
  • fever
  • chills
  • sore throat
  • headache
  • rash
  • itching
  • confusion, or
  • abnormal behavior

Dosage for Rifamate

The recommended dosage of Rifamate is two capsules taken one hour before or two hours after a meal once a day. Liver function tests should be performed prior to taking Rifamate as it may cause liver dysfunction, especially if you have liver disease.

What Drugs, Substances, or Supplements Interact with Rifamate?

Tell your doctor if you take drugs such as acetaminophen or consume alcohol on a regular basis as these may increase your risk of liver damage.

Rifamate During Pregnancy or Breastfeeding

Caution should be taken if you are pregnant or breastfeeding while taking Rifamate.

Additional Information

Our Rifamate (rifampin and isoniazid) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Rifamate Consumer Information

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Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • nausea, upper stomach pain, feeling weak or tired, loss of appetite, dark urine, clay-colored stools, 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 your skin.

Common side effects may include:

  • 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.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Rifamate (Rifampin and Isoniazid)


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Rifamate Professional Information



Gastrointestinal: heartburn, epigastric distress, anorexia, nausea, vomiting, jaundice, flatulence, cramps, and diarrhea have been noted in some patients. Although Clostridium difficile has been shown in vitro to be sensitive to rifampin, pseudomembranous colitis has been reported with the use of rifampin (and other broad spectrum antibiotics). Therefore, it is important to consider this diagnosis in patients who develop diarrhea in association with antibiotic use.

Hepatic: transient abnormalities in liver function tests (e.g., elevations in serum bilirubin, alkaline phosphatase, serum transaminases) have been observed. Rarely, hepatitis or a shock-like syndrome with hepatic involvement and abnormal liver function tests has been reported.

Hematologic: thrombocytopenia has occurred primarily with high dose intermittent therapy, but has also been noted after resumption of interrupted treatment. It rarely occurs during well supervised daily therapy. This effect is reversible if the drug is discontinued as soon as purpura occurs. Cerebral hemorrhage and fatalities have been reported when rifampin administration has been continued or resumed after the appearance of purpura. Rare reports of disseminated intravascular coagulation have been observed. Leukopenia, hemolytic anemia, and decreased hemoglobin have been observed.

Agranulocytosis has been reported rarely.

Central Nervous System: headache, fever, drowsiness, fatigue, ataxia, dizziness, inability to concentrate, mental confusion, behavioral changes, muscular weakness, pains in extremities, and generalized numbness have been observed.

Psychoses have been rarely reported.

Rare reports of myopathy have also been observed.

Ocular: visual disturbances have been observed.

Endocrine: menstrual disturbances have been observed.

Rare reports of adrenal insufficiency in patients with compromised adrenal function have been observed.

Renal: elevations in BUN and serum uric acid have been reported. Rarely, hemolysis, hemoglobinuria, hematuria, interstitial nephritis, acute tubular necrosis, renal insufficiency, and acute renal failure have been noted. These are generally considered to be hypersensitivity reactions. They usually occur during intermittent therapy or when treatment is resumed following intentional or accidental interruption of a daily dosage regimen, and are reversible when rifampin is discontinued and appropriate therapy instituted.

Dermatologic: cutaneous reactions are mild and self-limiting and do not appear to be hypersensitivity reactions. Typically, they consist of flushing and itching with or without a rash. More serious cutaneous reactions which may be due to hypersensitivity occur but are uncommon.

Hypersensitivity reactions: occasionally, pruritus, urticaria, rash, pemphigoid reaction, erythema multiforme including Stevens-Johnson syndrome, toxic epidermal necrolysis, Drug Reaction with Eosinophilia and Systemic Symptoms syndrome (see WARNINGS), vasculitis, eosinophilia, sore mouth, sore tongue, and conjunctivitis have been observed.

Anaphylaxis has been reported rarely.

Miscellaneous: edema of the face and extremities has been reported. Other reactions which have occurred with intermittent dosage regimens include "flu" syndrome (such as episodes of fever, chills, headache, dizziness, and bone pain), shortness of breath, wheezing, decrease in blood pressure and shock. The "flu" syndrome may also appear if rifampin is taken irregularly by the patient or if daily administration is resumed after a drug free interval.


The most frequent reactions are those affecting the nervous system and the liver. (see BOX WARNING).

Nervous system: peripheral neuropathy is the most common toxic effect. It is doserelated, occurs most often in the malnourished and in those predisposed to neuritis (e.g., alcoholics and diabetics), and is usually preceded by paresthesia of the feet and hands. The incidence is higher in "slow inactivators."

Other neurotoxic effects, which are uncommon with conventional doses, are convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment, and toxic psychosis.

Gastrointestinal: pancreatitis, nausea, vomiting, and epigastric distress.

Hepatic: elevated serum transaminases (SGOT; SGPT), bilirubinemia, bilirubinuria, jaundice, and occasionally severe and sometimes fatal hepatitis. The common prodromal symptoms are anorexia, nausea, vomiting, fatigue, malaise, and weakness. Mild and transient elevation of serum transaminase levels occurs in 10 to 20% of persons taking isoniazid. The abnormality usually occurs in the first 4 to 6 months of treatment but can occur at any time during therapy. In most instances, enzyme levels return to normal with no necessity to discontinue medication. In occasional instances, progressive liver damage occurs, with accompanying symptoms. In these cases, the drug should be discontinued immediately. The frequency of progressive liver damage increases with age. It is rare in persons under 20, but occurs in up to 2.3% of those over 50 years of age.

Hematologic: agranulocytosis, hemolytic sideroblastic or aplastic anemia, thrombocytopenia, and eosinophilia.

Hypersensitivity reactions: fever, skin eruptions (morbilliform, maculopapular, purpuric, or exfoliative), lymphadenopathy, anaphylactic reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis (see WARNINGS, Isoniazid), Drug Reaction with Eosinophilia and Systemic Symptoms syndrome (see WARNINGS), and vasculitis.

Metabolic and endocrine: pyridoxine deficiency, pellagra, hyperglycemia, metabolic acidosis, and gynecomastia.

Miscellaneous: rheumatic syndrome and systemic lupus erythematosus-like syndrome.

Read the entire FDA prescribing information for Rifamate (Rifampin and Isoniazid)

© Rifamate Patient Information is supplied by Cerner Multum, Inc. and Rifamate Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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