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Rifamate Side Effects

Generic name: isoniazid / rifampin

Medically reviewed by Last updated on Jul 13, 2021.

Note: This document contains side effect information about isoniazid / rifampin. Some of the dosage forms listed on this page may not apply to the brand name Rifamate.

For the Consumer

Applies to isoniazid/rifampin: oral capsule


Oral route (Capsule)

Severe and sometimes fatal hepatitis has been reported with isoniazid therapy and may occur even after many months of treatment. The risk for hepatitis generally increases with advancing age and alcohol use. Monthly clinical evaluation and liver function tests should be performed. Instruct patients to report immediately any of the prodromal symptoms of hepatitis, such as fatigue, weakness, malaise, anorexia, nausea, or vomiting. If these symptoms appear or if signs suggestive of hepatic damage are detected, isoniazid should be discontinued promptly. If isoniazid must be reinstituted, it should be reinstituted only after symptoms and laboratory abnormalities have cleared. The drug should be restarted in very small and gradually increasing doses and should be withdrawn immediately if there is any indication of recurrent liver involvement. Treatment should be deferred in persons with acute hepatic diseases.

Side effects requiring immediate medical attention

Along with its needed effects, isoniazid / rifampin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking isoniazid / rifampin:

More common

  • Clumsiness or unsteadiness
  • dark urine
  • loss of appetite
  • nausea and vomiting
  • numbness, tingling, burning, or pain in the hands and feet
  • unusual tiredness or weakness
  • yellow eyes or skin

Less common


  • Bloody or cloudy urine
  • blurred vision or loss of vision, with or without eye pain
  • convulsions (seizures)
  • depression
  • greatly decreased frequency of urination or amount of urine
  • mood or mental changes
  • sore throat
  • unusual bleeding or bruising

Side effects not requiring immediate medical attention

Some side effects of isoniazid / rifampin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

  • Sore mouth or tongue

For Healthcare Professionals

Applies to isoniazid / rifampin: oral capsule


Doses greater than 600 mg of rifampin given once or twice weekly have resulted in a higher incidence of adverse reactions, including the "flu syndrome" (fever, chills, malaise); hematopoietic reactions (leukopenia, thrombocytopenia, acute hemolytic anemia); shortness of breath; shock; anaphylaxis; renal failure; and cutaneous, gastrointestinal, and hepatic reactions.[Ref]


Frequency not reported: Vasculitis


Frequency not reported: Flushing, decreased blood pressure[Ref]


Frequency not reported: Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome, Stevens-Johnson syndrome, Toxic Epidermal Necrolysis (TEN), rash


Frequency not reported: Acne, exfoliative dermatitis, pemphigus


Frequency not reported: Erythema multiforme, skin reaction, pruritus, pruritic rash, urticaria, allergic dermatitis, pemphigoid, sweat discoloration, cutaneous reactions[Ref]



Frequency not reported: Gynecomastia, hyperglycemia


Rare (less than 0.1%): Adrenal insufficiency

Frequency not reported: Menstrual disorder/disturbances[Ref]


Frequency not reported: Nausea, vomiting, epigastric distress, diarrhea


Frequency not reported: Constipation, dry mouth, pancreatitis


Frequency not reported: Gastrointestinal disorder, abdominal discomfort, heartburn, flatulence, cramps, pseudomembranous colitis, sore mouth, sore tongue[Ref]


Frequency not reported: Thrombocytopenia, eosinophilia, agranulocytosis, hemolytic anemia


Frequency not reported: Anemia, aplastic anemia, lymphadenopathy


Uncommon (0.1% to 1%): Leukopenia

Rare (less than 0.1%): Disseminated intravascular coagulation

Frequency not reported: Decreased hemoglobin[Ref]


Frequency not reported: Hepatitis, elevated serum transaminases (SGOT, SGPT), bilirubinemia, bilirubinuria, jaundice


Common (1% to 10%): Elevated alkaline phosphatase

Rare (less than 0.1%): Abnormal liver function, shock-like syndrome with hepatic involvement

Frequency not reported: Hyperbilirubinemia[Ref]



Rare (less than 0.1%): Anaphylaxis[Ref]



Frequency not reported: Pellagra, pyridoxine deficiency, metabolic acidosis


Frequency not reported: Decreased appetite, anorexia[Ref]



Frequency not reported: Systemic lupus erythematosus-like syndrome, rheumatic syndrome


Rare (less than 0.1%): Myopathy

Frequency not reported: Muscle weakness, bone pain[Ref]

Nervous system

Peripheral neuropathy associated with isoniazid is dose-dependent, most often occurs in malnourished patients and in patients predisposed to neuritis (such as alcoholics and diabetics), and generally follows paresthesias of the hands and feet. The rate is higher in slow acetylators.[Ref]


Common (1% to 10%): Peripheral neuropathy

Uncommon (0.1% to 1%): Convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment

Frequency not reported: Vertigo, polyneuritis (presenting as paresthesia, muscle weakness, loss of tendon reflexes)


Frequency not reported: Headache, drowsiness, cerebral hemorrhage, ataxia, dizziness, inability to concentrate, muscular weakness, pains in extremities, generalized numbness[Ref]



Frequency not reported: Tear discoloration, visual disturbances, conjunctivitis[Ref]


Frequency not reported: Fever


Frequency not reported: Anti-nuclear antibodies


Frequency not reported: Influenza-like syndrome, post-partum hemorrhage, fetal-maternal hemorrhage, porphyria, edema, fatigue, facial edema, edema of the extremities, shock[Ref]



Frequency not reported: Toxic psychosis


Frequency not reported: Psychotic disorder/psychoses, mental confusion, behavioral changes[Ref]



Rare (less than 0.1%): Hemolysis, hemoglobinuria, hematuria, interstitial nephritis, acute tubular necrosis, renal insufficiency, acute renal failure

Frequency not reported: Acute kidney injury, chromaturia, increased blood creatinine, elevated BUN, elevated serum uric acid[Ref]



Frequency not reported: Dyspnea, wheezing, discolored sputum, shortness of breath[Ref]


1. "Product Information. Rifamate (isoniazid-rifampin)." Aventis Pharmaceuticals, Kansas City, MO.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.